Nanolyser Final Report
Published on: Mar 3, 2016
Transcripts - Nanolyser Final Report
Nano Final Report:
NANOLYSER for Prostate Detection
S. Heglas MWF 3:00
Date of Assignment: 4/13/15
Date of Submission: 4/27/15
Prostate cancer is a serious concern that is affecting men. In the US, it is the second most
common cancer in men, second to only skin cancer. Two preliminary tests are available for the
diagnosis of the cancer, the PSA blood test and the digital rectum exam (DRE). The only test that
can provide definitive results is the prostate biopsy. Problems among these include invasive
procedures, costs, and slow results. As a result, a need can be identified for the development of a
non-invasive device that gives quick results at a lower cost than current tests. Through an extensive
research and development process, a device called the Nanofunctionalized Assay Nested in an
Onboard Laboratory Yielding Specific Expeditious Results chip, or the NANOLYSER, was
created. It is able to detect the levels of PSA, a biomarker for prostate cancer, in a drop of blood
to give the user an indication if further action is necessary. It utilizes a silicon nanowire with PSA-
AB, an antibody to which PSA adheres, and a constant voltage across the wire to detect the level
of PSA. The higher the concentration of PSA, the greater increase experienced by the current. This
increase is used to tell the concentration of PSA. Main components of the device include
microneedles for obtaining a sample of blood, the nanowire, microchannels for housing the
nanowire, an ammeter base, and a suction ball to aid in the movement of sample through the
channel. The NANOLYSER is able to give a concentration of PSA in the blood. This can be
compared to average values of PSA for a man’s age and ethnicity or to previous concentration
tests. Future improvements for the device include device refinement in terms of the housing, the
development of a built-in ammeter for the device, and an automated pumping system to make the
device easier to use.
Table of Contents
1. INTRODUCTION 1
1.1. Team Introduction and Problem Statement 1
1.2. Report Organization 1
2. NANO DESIGN BACKGROUND 2
2.1. Medical Applications 2
2.1.1. Disease Diagnostics 2
2.2. Nano Fabrication Techniques 3
2.2.1. Top-Down 3
2.2.2. Bottom-Up 3
2.2.3. Other Processes 4
2.3. Disease to Be Diagnosed 4
2.3.1. Current Methods of Diagnosis 5
3. BRAINSTORMING AND PRELIMINARY CONCEPTS 6
3.1. Requirements and Constraints 6
3.2. Team Brainstorming Process 7
3.2.1. Individual Ideas 7
184.108.40.206. Disease and Analyte 7
220.127.116.11. Loading and Movement of Sample 7
18.104.22.168. Identification of Analyte 8
22.214.171.124. Reading of Results 8
3.2.2. Idea Selection Process 9
4. DESIGN CONSIDERATIONS 9
4.1. Ideal Operation 9
4.1.1. User Interaction 10
4.1.2. Sample Loading 10
4.1.3. Movement and Detection 11
4.2. Fabrication Considerations 11
4.3. Biological and Biochemical Considerations 12
4.4. Disease Diagnosis 12
5. DESIGN ANALYSIS 13
5.1. Decision Making Process 13
5.1.1. Choice for Disease and Analyte 13
5.1.2. Movement of Sample 14
5.1.3. Reading of Results 14
5.2. Design Parameters 15
5.2.1. Cost and Size Limitations 15
5.2.2. Reusability 16
5.2.3. Ease of Use 16
6. FINAL DESIGN 17
6.1. Overall Chip Design 17
6.1.1. Microscale Features 19
126.96.36.199. Microfluidics 19
188.8.131.52. Microneedle 20
6.1.2. Nanoscale Features 22
184.108.40.206. Nanowire 22
6.2. Fluid Circuits 24
6.2.1. Loading of Sample 24
6.2.2. Fluid Driving Force 25
6.3. Detection Method 26
6.3.1. Disease and Analyte 26
6.3.2. Detection Method 26
6.3.3. Steps for Detection 27
6.3.4. Reading of Results 28
6.3.5. Accuracy and Speed of Results 29
6.4. Cost of Materials 29
6.4.1. Disposability 30
6.5. Improvements on Current Methods 31
7. SUMMARY AND CONCLUSIONS 31
7.1. Conclusion 31
7.1.1. Importance of Design 32
7.1.2. Future Work 32
7.2. Acknowledgements 33
8. BIBLIOGRAPHY 33
9. APPENDIX A – FIGURES AND TABLES A1
10. APPENDIX B – EQUATIONS AND CALCULATIONS B1
List of Figures
Figure No. Description Page
1 The assembly of the NANOLYSER as assembled in SolidWorks 18
2 The exploded assembly of the NANOLYSER in SolidWorks 18
3 Detail of the channels on the bottom of the PDMS chip 19
4 The microneedle for blood sample attraction modeled in SolidWorks 21
5 The nanowire to be used in the channels for PSA detection 23
6 A graph of current versus PSA level for 25 patients 28
A1 The top of the PDMS chip A2
A2 View of the assembly from the side A2
A3 View of the assembly from the bottom A3
A4 Side profile of the assembly A3
A5 View of the assembly from the top A4
A6 Glass plate for the top of the NANOLYSER A4
A7 Top-down view of the nanowire in SolidWorks A5
A8 Detailed view of the bends in the nanowire A5
A9 Graph of PSA levels and age for three different ethnicities A6
List of Tables
Table No. Description Page
1 Individual part quantities and costs for the NANOLYSER 30
A1 Data for PSA levels and current values over nanowire A6
1.1. Team Introduction and Problem Statement
Nanotechnology has a far-reaching range of applications from improved batteries to biomedical
applications. The discipline has gained a great deal of attention from the scientific and medical
communities with its numerous advantages to conventional methods of certain processes. One
such process is disease diagnosis. Where some diseases may have taken large volumes of blood
and days in a laboratory to detect, nano and micro based devices can allow for diagnosis to occur
with extremely small samples in a much timelier manner. Our Cell Entrapment and Novel Sensing
Endeavors team, comprised of Joseph Adams, Nate Olson, and Joshua Rawlins, has been
designated to design a device that uses a sample of blood for disease diagnosis. This device,
officially named the Nanofunctionalized Assay Nested in an Onboard Laboratory Yielding
Specific Expeditious Results chip (NANOLYSER), must use nanoscale features and microfluidics
to detect an analyte in a sample of blood and indicate the disease state of a patient . The team
chose to focus on the diagnosis of prostate cancer and designed our NANOLYSER to test for the
1.2. Report Organization
In the subsequent sections, the design of the NANOLYSER device will be discussed in detail. The
following section, Section 2, gives a background on nanotechnology and how it relates to medical
applications, including fabrication. A brief description of the disease diagnosed by the device is
also communicated. Section 3 presents the brainstorming process the team followed in the design
process. Sections 4 and 5 cover the analysis of the design and considerations that had to be taken
into effect when formulating the NANOLYSER concept and design. Following, Section 6
includes a detailed description of the final design chosen for the nano device is presented, along
with the specifics on its functionality. Additionally, its merits when compared to current methods
of diagnosis are indicated. Lastly, within Section 7, the design process is synopsized along with
potential avenues for further work.
2. Nano Design Background
2.1. Medical Applications
Nanotechnology is utilized in a number of diverse areas of science and research. Being a relatively
new technology, the use of nanocomponents for accomplishing tasks that are currently costly or
time consuming. One such area that is discussed in further detail below is disease diagnostics.
2.1.1. Disease Diagnostics
An area that nanotechnology may someday revolutionize due to its numerous benefits is disease
diagnostics. Many nano-scale applications relating to disease diagnostics have not yet been
commercialized and are still in laboratory research phase. Many proof of concept devices have
been created, but are not yet ready for mass use. Using nano-scaled features on microfluidic
devices may provide rapid diagnosis for a number of diseases and medical conditions, completing
diagnoses in one visit that currently take days for lab tests to be conducted. A variety of methods
are under study for disease detection. Included in current research are carbon nanotubes, gold
nanoparticles, quantum dots, and nanowires. These methods take advantage of specific analytes
that are only present, or present in high enough quantities, when a person has a given disease.
Physics, chemistry, and biology are all relevant when it comes to the creation and design of such
a nano-based device. The methods utilize the electrical, optical, and physical properties of the
analytes to give results of a disease state in short periods of time .
2.2. Nano Fabrication Techniques
Nanotechnology is an emerging technology and there are a number of manufacturing methods for
producing the wide variety of nanoscale components. Depending on the intended application and
materials used, the technique for fabrication can vary greatly. A brief discussion of examples of
fabrication techniques follows in this section.
Top-down manufacturing is the most widespread and researched technique of fabrication of
nanoscale components. In top-down nanofabrication, a larger piece of material is cut down and
reduced down to the nanoscale. There are a number of methods utilized, including lithography
and deposition. The process is similar to carving an object from a larger block of material. This
approach to nanofabrication requires a greater amount of material and can lead to large amounts
of waste .
Bottom-up nanofabrication involves the self-assembly of structures at the nanoscale. This is
completed though material, chemical, or biological based process. Nano reactions result in a final
structure that require a minimal amount of material. It can be thought of as atom-by-atom
manufacture of a component. Though efficient in use of material, the nano reactions can be
difficult to control and must be discovered through research in chemistry and biochemistry of the
atoms used .
2.2.3. Other Processes
A number of new and potentially groundbreaking processes for nanofabrication are currently being
researched. Nanotube production, nanoparticle creation, and a number of new lithography
processes are being looked at as a new standard for manufacturing at the nanoscale. Nanoparticles
can be created using a variety of processes, including mechanical milling, controlled detonation
synthesis, and plasma processing. The area garnering the most interest is the fabrication of
nanotubes, though high cost is a current obstacle .
2.3. Disease to Be Diagnosed
The disease that will be diagnosed by the NANOLYSER is prostate cancer. Prostate cancer is
cancer of the prostate gland. The prostate is a gland in men that secretes a fluid that helps to protect
and nourish sperm cells in semen . Prostate cancer most commonly begins as an
adenocarcinoma, or tumor that starts in gland cells. Another way the cancer can begin is in the
form of a sarcoma, or a type of tumor that begins in soft tissues of the body, but this is quite rare.
Symptoms of prostate cancer include problems passing urine, blood in urine, and pain in the back,
hips, or other surrounding areas, among other symptoms.
Prostate cancer the second most common cancer in men, after only skin cancer . However, there
is not as much funding and publicity for it when compared to other major cancers like breast and
skin cancer. Also, current detection methods are expensive and invasive, leading many men into
not getting checked. As a result, there is a need for a quick, cheap, and painless preliminary
screening device to test for prostate cancer. This could lead to a reduction in unnecessary spending
on testing, accounting for billions in medical spending .
2.3.1. Current Methods of Diagnosis
Currently, prostate cancer can only be diagnosed with a prostate biopsy. This procedure involves
a hollow needle being inserted through the wall of the rectum and into the prostate. When it is
removed, the hollow part of the needle will contain a sample of prostate tissue. This process is
repeated anywhere from 8 to 18 times, though on average 12 times. Overall, the process is
considered uncomfortable, with pain inflicted upon the insertion of the needles. Symptoms from
the process also include soreness and blood in urine and semen. The samples are sent to a lab,
where they are studied under a microscope to see if any cancer cells are present.
While the biopsy is the only way that prostate cancer can be affirmed, initial screening for the
cancer can be completed in two different ways, a blood test for prostate-specific antigen (PSA) or
a digital rectal exam (DRE). PSA is a protein that is made only by cells in the prostate gland of
men. For the most part, it is found in semen, but it can also be found in blood. Normal levels of
PSA has been found to be about 4 nanograms per milliliter, though this number can change from
man to man based on factors such as age, prostate size, and use of certain prescription medicines.
Blood tests can measure the amount of PSA in the blood. These tests are mostly completed in a
doctor’s office, though at home testing kits are available. Though this is a good way of testing for
prostate cancer, it is not as reliable as a biopsy. For example, a man with PSA levels between 4
and 10 nanograms per milliliter, their chance of having the cancer is 25%. Above 10, the chance
increases to 50% .
DREs are a much more invasive test. They involve a doctor sticking a gloved hand into the rectum
to feel the back of the prostate for any bumps or other abnormalities on the prostate that could be
a sign of cancer. While it is also not as exact as a biopsy, it does have a chance of finding cancers
in men with normal levels of PSA.
3. Brainstorming and Preliminary Concepts
3.1. Requirements and Constraints
The NANOLYSER must be able to perform a set of tasks in order to give a positive or negative
reading for a given analyte in a sample of blood. The analyte must serve as an indication of the
presence of a certain disease. There are a number of options to perform such an analysis. A
process must be used to separate the analyte from the blood. Once separated, a detection strategy
is employed to give the user a result of the presence of the analyte, which will then give an
indication of the disease state from the blood sample. A fluid circuit is required that can load the
blood sample and any reagents needed, which must also separate or capture the analyte. The fluid
needs to be driven through the channel by some driving force, but the user must have minimal
interaction with the NANOLYSER. Interaction with the user is limited to loading the sample and
inserting the device into a reader. The device must either be reusable or disposable, in addition to
being cost effective .
3.2. Team Brainstorming Process
3.2.1. Individual Ideas
Prior to making any team-based design decisions, each member of the team brainstormed solutions
for the problem statement. Ideas for the choice of disease, how the sample was to be moved, and
the detection method were formed following thorough research on nanotechnology and disease
220.127.116.11. Disease and Analyte
Many illnesses were researched for diagnosis using the NANOLYSER. Of particular interest were
neurodegenerative disorders and congenital genetic disorders. In addition, prostate cancer was
also researched. For the neurodegenerative diseases, Alzheimer’s and Parkinson’s were the two
diseases primarily focused upon. Early detection for such diseases is possible from separating
fetal DNA present in the blood of the mother. Prostate cancer can be detected through the use of
PSA, prostate specific antigen, also present in the blood of the patient. The general analytes used
in disease diagnostics using a sample of blood were found to include proteins and cell geometry.
18.104.22.168. Loading and Movement of Sample
Movement of samples and reagents would be best accomplished using the concepts of
microfluidics. Liquids are known to behave differently on the microscale and this behavior had to
be taken into effect when brainstorming designs for the NANOLYSER. One idea was to use a
pressure differential generated by suction from a part of the reading device. Capillary action was
researched as a potential method of sample movement, in addition to the use of magnetic
attractions to move the sample through the chip. The consensus for loading of blood was a simple
prick of the finger to supply a droplet of blood for testing. A unique idea presented was the use of
a microneedle to extract the blood from the finger of the user.
22.214.171.124. Identification of Analyte
Identification of the analyte was an important phase of the brainstorming process and typically
involved components on the nanoscale. Ideas that were included in individual research was
nanowires, nanopillars, magnetic beads, microwells, centrifugal, and guided-mode resonance.
Each identification method typically paired with a certain disease and corresponding analyte. For
example, nanowires worked best for identifying PSA from a sample of blood for prostate cancer.
Nanopillars were coated with antibodies that could then bond to specific antigens, similar to the
nanowire. Magnetic beads also use antigen-antibody bonding for the detection of a disease. The
beads bond to the cells with specific proteins and are separated out by magnetic attraction.
Microwells and centrifugal techniques utilized the unique cell shapes and sizes to physically
separate out a target analyte.
126.96.36.199. Reading of Results
The method of reading results depended heavily upon the components utilized for identification
of the analyte. If nanowires are used, the conductance of the wire is used to read results from the
test of a sample of blood. The change in conductivity can be related to the concentration of analyte.
A device with nanopillars is flushed with a fluorescent nanoparticle solution following the blood
sample injection. The luminosity would then be quantified by the reader and used to determine
the likelihood of a disease state. Guided-mode resonance also used luminescence to quantify the
amount of analyte separated out from the blood. Another technique researched was the use of
DNA probes inserted into the sample following injection of a protein.
3.2.2. Idea Selection Process
The selection of ideas was performed by the team as a whole. All ideas were presented in an open
manner and had their merits discussed. Team members met following individual brainstorming.
Each member discussed their ideas for each aspect of the NANOLYSER device and the process
of idea selection followed a sequential pattern. The first decision that had to be made was the
choice for disease. The other features of the NANOLYSER heavily depended upon the disease
chosen. The analyte was the second decision that had to be made, which stemmed from the choice
for disease. The identification of the analyte was then discussed, along with the specific method
followed for any necessary separation and sample transport.
4. Design Considerations
4.1. Ideal Operation
A NANOLYSER operates ideally if it returns a diagnosis of a disease quickly with minimal
interaction on the part of the user. The chip must be able to perform the diagnostics using a sample
of blood, preferably a minimal volume. This is in contrast to many existing methods of diagnostics
that are utilized in hospital setting currently. Blood analysis processes used require large samples
of blood that must be drawn from the user. The results from these tests can require days in a
laboratory to return results. The use of nanotechnology and microfluidics on small device, such
as the NANOLYSER, can be used to return results almost immediately with extremely small
sample volumes. Further discussion of the operation of an ideal NANOLYSER follows in
4.1.1. User Interaction
The goal of the design was to minimize user interaction with the chip. It was stated in the project
statement that human interaction was limited to loading the sample and any required reagents and
inserting the chip into the reader. The team’s goal was to achieve this purpose using a device that
could painlessly take a sample of blood and introduce it to the device in a simple, one step process.
Consideration was given to both the method of blood extraction and introduction to the chip.
Research was performed that looked into devices to perform such a task. The only other interaction
with the NANOLYSER required on the part of the user is plugging the device into a reader. With
the system utilized by the team for detection, the reader is an ammeter and requires two cords to
be plugged into ports on the chip. The microammeter is powered by a 9V battery and requires no
other equipment or knowledge to operate, making the interaction with the chip as minimal and
simple as possible.
4.1.2. Sample Loading
The blood sample must be somehow introduced into the channels of the chip. Any reagents
requires for the detection of the analyte must also be loaded onto the chip. This could be performed
in a number of ways and the user may interact with the device in order to do so. A consideration
that must be made is comfort of the patient. Many people have an aversion to needles and
traditional methods of blood sample collection. In addition to patient comfort, it would be best to
have a device that would both extract the blood from the patient and introduce it into the
microchannels without any outside user input.
4.1.3. Movement and Detection
On a small-scale device, fluids behave in much different ways than in larger channels. The
intricacies of microfluidics and behavior of blood, specifically, must be taken into account when
designing the channels for fluid transport through the device. Research was performed into the
use of pumps or other devices to create flow, though capillary action seemed to be the most
promising based upon its simplicity. Articles were found that explored capillary action and blood
flow in microfluidic channels. The design for the channels was based upon this research to ensure
that the droplet of blood from the patient would consistently travel through the channel and allow
for detection. Methods of detection related to the biological and biochemical makeup of the blood
and is discussed in further detections. The general consideration for detection was a system that
would return results in a timely manner while maintaining accuracy and consistency.
4.2. Fabrication Considerations
A detailed explanation of nanotechnology fabrication methods came prior in the report. In these
sections, the varying methods of nanofabrication were introduced and briefly explained. Though
considerations must be made for the entire chip, most complexities arise when looking at the
nanoscale features of the NANOLYSER. The entire device must be able to be manufactured using
methods currently available that have been proven to work. In addition to being an existing
method, it must also be economical and sustainable. If the NANOLYSER is to be mass produced,
it cannot be overly expensive or complex in nature. A complex manufacturing method may lead
to long production times that would not be preferential when creating a device for the mass market.
4.3. Biological and Biochemical Considerations
Any reagents used in the detection of the analyte must not react in an adverse way with the sample
of blood. In addition, it must be ensured that the blood or reagents do not react with materials used
in the manufacture of the chip and related components. The makeup of the blood is of importance
and how it relates to the detection of the analyte we have chosen for the detection of prostate
cancer. The properties of the analyte allow for the detection to occur, so the biological and
biochemical characteristics of the analyte must be studied so that the results of the test can be
accurate, consistent, and returned quickly.
4.4. Disease Diagnosis
Thought has to be put into both the disease chosen and the manner in which the disease will be
detected. The disease must somehow be detected through the use of a sample of blood. In addition
to being present in the blood, a known analyte must exist that can be detected from the blood. The
analyte for blood analysis is typically a protein. Proteins can be a sign of a bodily response to a
disease or infection . These proteins often have unique geometries or chemical properties that
allow them to be detected in a sample of blood. Another potential analyte is RNA or DNA
messengers. Though all options were considered, the use of a protein, and the utilization of its
unique chemical properties, made the most sense as the manner of detection. As for the disease,
the greatest consideration was put into finding a disease for which methods of diagnosis are
lacking. A disease whose diagnosis requires tests that are invasive, expensive, or difficult would
make the best candidate for the NANOLYSER since the goal is an improvement of current
5. Design Analysis
5.1. Decision Making Process
The decision making process was performed by the team after debating the positive and negative
aspects of individual ideas. Decisions had to be made on the disease and analyte, movement of
the blood, and the method for reading results.
5.1.1. Choice for Disease and Analyte
As stated earlier, all individual ideas for the disease to be diagnosed were discussed. As more
research was performed, issues were found with the neurodegenerative diseases. Though studies
are currently being performed on finding an analyte for detection of such conditions, there has not
yet been a reliable protein or other indicator discovered. Some initial research has found
prospective proteins, but nothing has been proven to always return results. Prostate cancer was
the next condition to be decided upon. After further research was done for prostate cancer, it was
discovered that very little funding has been put into a simple method of diagnosis, despite a high
rate of the disease in men. Current methods are very invasive and costly. Prostate cancer was thus
decided upon as the disease for the NANOLYSER. The analyte was chosen to be PSA, the prostate
specific antigen. This is the most reliable biomarker that can serve as an indication as to the disease
state of a patient from a blood sample.
5.1.2. Movement of Sample
The goal of the NANOLYSER was to make the device as simple as possible to allow for quick
and reliable detection on a lab-on-a-chip device. Capillary action was the main source of
discussion when deciding upon a method of movement on the device. On the microscale, careful
consideration must be given to ensure that capillary action will in fact move the blood through the
channels. After an extensive search of journal articles, it was discovered that a reliable method to
cause capillary action has been created. This method is discussed in more detail in a subsequent
5.1.3. Reading of Results
With a disease and analyte decided upon, the method for reading results followed. A silicon
nanowire was to be used to measure the conductance through the microfluidic channel both before
and after introduction of a blood sample. The wire, coated in antibodies, would attract the antigens
from the blood. Research was done that compared the conductance in microamps following
exposure to blood and compared the change to the concentration of PSA in the patient’s blood.
The study and its impact on the design of the NANOLYSER are discussed in further detail
following later in the report. The actual reading would take place on a ammeter connected to the
NANOLYSER through two electrodes at the end of each wire. Conductance values are returned
very quickly and enable nearly instantaneous results. This allows a quick diagnosis to be made
with a very small sample size.
5.2. Design Parameters
There were certain parameters as stated in the NANOLYSER Project Statement . The
parameters included specifications on the device in terms of size and operation. In addition, there
were limitations and restrictions recognized by the members of the team.
5.2.1. Cost and Size Limitations
The goal of the NANOLYSER device was to create a small diagnostic tool that can quickly return
results with minimal cost. Once a design had been decided upon, the materials used to create the
individual components were discussed. Some of the parts had to be made out of a certain material
in order to facilitate the movement and detection included in the design. The size of the device is
approximately that of a USB drive, small enough to be easily transported and used in a variety of
environments. The wire would have to be made out of silicon in order to conduct electricity and
facilitate conductance readings. The costs associated with the fabrication of the nanowire are not
widely published, though estimates can be made. The channels for fluid flow would be made out
of PDMS, a relatively inexpensive polymer. The plates between which the chip with channels will
be located must be made from glass in order to allow for capillary action to occur with blood. An
ammeter must also be purchased, but this is necessary only once and of minimal cost when
compared to other medical equipment for disease diagnostics. Further discussion of the specific
costs involved are included in the Final Design section.
The initial goal of the NANOLYSER device was to make it reusable to minimize cost and
maximize the range of applications. As more research was performed, it was found that this was
not feasible. The antibodies used on the silicon nanowire would have to be somehow reapplied
and the channels would gradually lose their ability to cause capillary driven flow. Issues with
cross-contamination would arise with the use of a microneedle to extract a sample of blood from
the patient. Once the idea of reusability was abandoned, thought was put into a potential recycling
program involving the NANOLYSER.
5.2.3. Ease of Use
Ease of use was a major consideration when determining the design of the NANOLYSER. The
goal of the device was to create a disease diagnostic tool that could quickly return results with
minimal cost and equipment requirements. The interaction with the device on the part of the user
was to be minimalized. The ease of use for the design followed from the choices for extraction of
the sample and reading of the results. These are the only two stages in which the user is directly
involved. Both steps are not complicated and could be performed without any training or extensive
prior knowledge of the device’s function. To setup the device, the ammeter must be plugged into
two ports on the device, which are color coded to match up the plugs and ports. The ammeter is
battery powered and requires no other equipment to operate. Once plugged in, the user needs only
to push his or her finger onto the microneedle to extract a droplet of blood. After that, it is as
simple as recording the maximum conductance value and comparing the value to the included table
and prior results of the test, if applicable.
6. Final Design
6.1. Overall Chip Design
The chip consists of a PDMS chip with a microchannel shaped into the form of a chaotic mixer.
The PDMS chip is positioned between two glass plates. The two glass plates are attached to one
another using four bolts and nuts. The bolts go through four holes drilled on each glass plate. The
glass plates are tightened to create a seal between the channel and the glass. Two holes are drilled
into the top plate for entrance and exit ports that allow blood to be loaded and flushed out. Glass
was the material necessary to facilitate flow through capillary action. Oxygen plasma, the
chemical that is used to coat the channels for hydrophilicity, will bond only to glass. A more in-
depth discussion of this method follows in a later section. The key feature of the chip that allows
for detection is a silicon nanowire that follows the path and is contained within the channel. It
exits at the top of the chip and leads to two electrodes. The nanowire is coated in antibodies that
attract a specific antigen from the blood. An ammeter, capable of measuring the current within
0.1 µA, plugs into the chip to provide a means of measuring current changes once the blood sample
passes over the nanowire. The current change corresponds to a level of the antigen that gives a
result as to the disease state of the patient. Images of the assembly and exploded assembly modeled
in SolidWorks can be seen on the following page in Figure 1 and 2. Additional images of the
NANOLYSER are included in the Figures and Tables appendix as Figures A2 through A6.
Figure 1: An assembly of the NANOLYSER modeled in SolidWorks.
Figure 2: An exploded assembly of the NANOLYSER modeled in SolidWorks.
6.1.1. Microscale Features
The NANOLYSER device utilizes both microscale and nanoscale features in order to successfully
detect and diagnosis prostate cancer. Microscale features are used in extraction and movement of
the sample through the device. Further discussion of the microscale features follows.
Microfluidic concepts and features are used to move the fluid through the NANOLYSER. The
channel is 200 µm in width and 100 µm in height. The chip in which the microfluidic channels
are contained is made out of PDMS, similar to many lab-on-a-chip devices. The PDMS chip was
modeled in SolidWorks and images are included in Figure 3 below and Figure A1 in the Figures
and Tables appendix.
Figure 3: The microfluidic channels on the bottom of the PDMS chip.
These dimensions were chosen as a result of the study performed by Cito, et al. The dimensions
provided the quickest and most consistent capillary driven flow using a droplet of blood, similar
to the sample that will be used on the NANOLYSER. The study performed by Cito used varying
channel widths with a constant height. It was fabricated using PDMS polymer base and a curing
agent in a 10:1 ratio and cast over a mold. After an hour in a vacuum chamber to degas the PDMS,
it was cured for 4 hours at 65℃. Before being attached to a glass substrate, the channels were
exposed with oxygen plasma to cause the PDMS to become extremely hydrophilic. The
hydrophilicity created by the oxygen plasma allowed the blood to flow through the channel at an
initial rate of 23.18 mm/s before slowing after 2 seconds to a speed of 8.99 mm/s .
This portion of the device would likely be fabricated in-plane, as this is the most convenient
method available . This aspect of the device would be fabricated by silicon etching directly onto
the surface of the device. This region would act as an entrance port with the needle holes etched
into the device at the beginning of the channel.
Unfortunately, limitations exist for microneedles. The density and strength of in-plane
microneedles is limited . Additionally, microneedles that are not fabricated to a point can cause
skin damage. The microneedles must also penetrate the skin to obtain blood. This can lead to
obstructions in flow caused by the skin cells also transferred. Their limitations, however, are
reasonable for our design.
First, it is not required that the microneedles are very strong or durable. The device will be
disposable with only a one-time use. Further, any potential minimal skin damage is extremely non-
invasive in comparison to traditional methods for detection of prostate cancer and the damage
would be limited. As to obstructions in flow due to skin, these would not be significant. Because
the device is one-time use, skin would not accumulate in the microneedles over time. Any
immediate accumulation from one use would be very minimal. An image of the microneedle is
shown below in Figure 4.
Figure 4: Screenshot of the microneedle modeled in SolidWorks.
6.1.2. Nanoscale Features
In addition to microscale features, nanoscale features are also included in the design of the
NANOLSYER. In order to reach the levels of precision necessary for diagnosing a disease with
such small sample volumes, nanotechnology must be used. The nanoscale feature on the device
was a nanowire which would facilitate readings of the specific antigen sought after.
The nanowire is the nanoscale feature utilized on the device for detection and diagnosis of prostate
cancer. The nanowire is the most important feature of the chip and allows for results to be obtained
from the blood sample loaded into the fluid circuit. The nanowire is made out of silicon, which
gives it semiconducting properties. Silicon nanowires can be used to act as a transistor for
electrical detection of viruses and proteins in a solution, such as blood. The nanowire is coated in
a specific antibody that corresponds to an antigen present as a result of a certain disease or
condition. Once the antigen binds to the antibody, the conductance of the wire changes from the
baseline value for the wire. This method can be used for a variety of diseases, viruses, and other
medical conditions . The diameter of the silicon nanowire used in the NANOLYSER is 8 nm,
though this was scaled up to 0.05 mm for the SolidWorks model in order to provide clarity to the
function of the device. An image of the nanowire as modeled in SolidWorks can be found at the
end of the section in Figure 5. A view from the top and a more detailed look at the nanowire are
included in Figures A7 and A8 in the Figures and Tables appendix.
Nanowires can be manufactured in a number of methods. Methods of fabrication include self-
assembly of atom chains, photolithography, wet etching, and thermal oxidation. These methods
extend from the top-down and bottom-up methods presented earlier in the report. A balance must
be found between control of the fabrication and the costs involved. A study performed by Cheng,
et al., utilized wet anisotropic etching, local thermal oxidation, and photolithography. It compared
the designed width to the fabricated width. The three methods were chosen because they are
considered three of the most cost-effective methods of silicon nanowire fabrication. The widths
agreed the most when wet etching was utilized . Etching also makes the most sense when it
comes to the NANOLYSER wire design, since it includes multiple bends. Self-assembly methods,
such as oxidation, would not be as controllable when creating these complex features.
Figure 5: An image of the nanowire, designed to follow the microchannels, modeled in SolidWorks.
6.2. Fluid Circuits
As mentioned, the flow will be driven through capillary action. After the blood enters the device,
it will flow throughout the chaotic mixing channel by means capillary action. The channel is split
into multiple rows horizontally across the device. This is meant to prevent the flow from fully
realizing a steady state. If this were to occur, the blood would flow in a laminar fashion. Therefore,
the surface area of blood that would come in contact with the nanowire for detection of the antigen
would be minimized.
The chaotic mixer acts to maximize the contact area between different layers of the blood
containing differing concentrations of antigens by creating turbulent flow . This allows for
maximal and accurate detection of the concentration of PSA present in the blood that may
otherwise be misleading if the PSA is limited to only a portion of the blood sample.
This method serves to maximize detection without incurring any significant additional design
challenges or costs. The same equipment used for fabrication of the channel normally may be used.
The chaotic mixer requires no special chemical treatment or additional flow circuitry. It maximizes
detection solely by geometry .
6.2.1. Loading of Sample
Blood intake for the whole blood analysis will be accomplished by use of microneedles. The
microneedles will function by the user pressing his or her finger against an area comprising the
entrance port of the device. The microneedles will then rupture the skin and draw blood into the
device strictly through capillary action. The user need only allow a droplet sized amount of blood
to be drawn. This capillary movement of the blood into the device would continue through the
channel for analysis .
6.2.2. Fluid Driving Force
The fluid, in the case of the NANOLYSER, is blood which must be driven through the microfluidic
channels. As briefly discussed earlier, liquids act much differently on the microscale. The force
chosen for the NANOLYSER was capillary action. The study by Cito, et al., was successful in
making a droplet of bovine blood flow through a microchannel using only capillary action. With
a glass plate and a microchannel formed from PDMS, capillary-driven flow successfully occurred.
The channel was coated with oxygen plasma prior to assembly. The oxygen plasma treatment
made the channels extremely hydrophilic, which is the property that allowed capillary action to
occur with such readiness. It was stated earlier that the initial velocity was 23.18 mm/s, slowing
to 8.99 mm/s after approximately two seconds in the channel. The rate of deceleration slowed as
time progressed from time zero to two seconds . Since a similar setup is used in the
NANOLYSER, it can be expected that flow will also occur in its channels. Using the data obtained
from the study, it was concluded that the velocity would be sufficient to pass the blood sample
through the channels in a timely manner, likely in under two minutes.
To aid capillary action in moving the sample of blood through the microfluidic channels, a latex
bulb was added to the exit port on the NANOLYSER. The bulb would be similar to a pipet bulb.
Before the patient presses his or her finger down onto the microneedle, the bulb would be squeezed.
At this point, the patient would press his or her finger down and the bulb would be released,
creating suction through the channel and aiding in pulling blood through the channels across the
6.3. Detection Method
It had to be decided what disease was going to be detected and the method used for detection. The
choice for the analyte followed from the choice for disease. Using the known properties of the
analyte, a method could be developed for successful detection of prostate cancer. Further
discussion of the process follows.
6.3.1. Disease and Analyte
The disease that will be diagnosed by the NANOLYSER is prostate cancer. The analyte that will
be used to detect prostate cancer is called prostate specific antigen, or PSA. Research has shown
that elevated levels of PSA in a man’s blood can be a sign of prostate cancer. A normal level of
PSA in the blood is 4 nanograms per milliliter, though this value can fluctuate. PSA will adhere to
an antibody known as anti-PSA antibody, or PSA-AB. Using this relationship between PSA and
PSA-AB, the levels of PSA in the blood can be detected.
6.3.2. Detection Method
The analyte is detected in the blood through the use of antibodies bonded to the silicon nanowire.
The nanowires are able to detect and attract the sought after antigen, PSA, out of the blood that is
indicative of a patient’s prostate cancer state. The attachment of the antibody to the nanowire leads
to a change in the conductivity of the wire that can then be related to the PSA level. The antigens
and antibodies bond due to conjugate principles of the two molecules. If PSA is present in the
blood, the current passing through the wire increases. The bonding of PSA and resulting change
takes less than 100 milliseconds to complete, returning nearly instantaneous results .
The bonding of the antibody to the nanowire is accomplished through a multistep process. First,
the nanowire is placed in a solution of 3-phosphonopropionic acid. It is then incubated in
dicyclohexylcarbodiimide and N-hydroxysuccinimide. This process prepares the surface of the
silicon nanowire for the actual attachment of the antigen used, anti-PSA antibody, PSA-AB. After
incubation, a buffered saline solution of 50 µM PSA-AB is used to treat the wire, resulting in the
antibody bonding to the surface of the wire .
6.3.3. Steps for Detection
The number of steps for the process of detection has been minimized in the design for the
NANOLYSER. The attempt was made to minimize the number of steps to ensure consistent and
accurate detection. Though many blood analysis devices require different components of the blood
to be separated out, our NANOLYSER design can return results using whole blood. This can be
accomplished due to the method of detection and the analyte chosen, PSA. PSA can be detected
in blood using a whole sample of blood and requires no separation. The chip comes pre-assembled,
so nothing must be put together once received by the hospital. The ammeter must be connected to
the two ports on the chip. The patient must push his finger onto the microneedle in order to extract
a droplet of blood for testing. Once the blood has entered the channel, the user of the device must
read the ammeter and record the maximum current achieved in µA while the blood flows through
the channel. Further explanation of the reading of results follows in the next section.
6.3.4. Reading of Results
When blood flows through the nanochannels, PSA in the blood adheres to the PSA-AB on the
nanowire. This causes a change in the conductivity of the wire. A constant voltage is applied across
the nanowire throughout the test. The change in conductivity with the constant voltage results in a
change in the current through the wire. From experiments conducted by S.M. Ushaa and his
associates, the current values for various levels of PSA in the blood can be seen below in Figure 6
The value from a reading of the test can be compared to the graph, or plugged into the equation of
the graph. The equation and an example PSA level calculation is shown in Equation B1 in the
Equations and Calculations appendix. This will give the amount of PSA in the blood, which can
Figure 6: Graph of current (µA) versus PSA level (ng/mL) for 25 patients.
be then compared to the average amount of PSA. The table including all data used to create the
graph that has PSA levels and current values is in the Figures and Tables appendix in Table A1.
Also included in the same appendix is a graph that compares PSA level and age for three different
races in Figure A9 .
6.3.5. Accuracy and Speed of Results
As stated before, the bonding of PSA and resulting change takes less than 100 milliseconds to
complete the bonding. This shows that the process is very fast to complete. As for accuracy, the
nature of the PSA level test is not very exact. This test is meant as an addition to a yearly checkup
of a man. Elevated levels do not necessarily mean prostate cancer, but it means an increased
chance. A man with PSA levels between 4 and 10 nanograms per milliliter, has a 25% of having
prostate cancer. Above 10, the chance increases to 50% . The microammeter has an accuracy
of 0.1 µA, within the necessary precision for making a determination from the results of the test
6.4. Cost of Materials
The materials used in the NANOLYSER are glass for the two plates, PDMS for the microchannel-
containing chip, four steel screws, and a silicon nanowire. A glass sheet 18in x 24in x .25in can
be bought from Home Depot for $6.48. Each chip holder is about 1.575in x 3.150in x .25in. This
means about 80 holders can be made for about $0.08 a piece, or $0.16 per unit . The Sylgard
184 Silicone Elastomer Kit can be bought for $59.38 for a 0.5 kg kit. From this kit, about 24 chips
can be made, using about 14 mL of base and 1.5 mL of curing agent per chip. This means that each
chip to produce would cost $2.50 . The specific cost of silicon nanowires is not well
documented or readily available. Many articles have made mention of groundbreaking processes
that allow nanowires to be produced for a low cost. The microammeter can be purchased through
Fisher Scientific for $86.25 and operates on a 9V battery . If purchased by a hospital or clinic,
only one micoammeter would have to be purchased for essentially an unlimited number of tests.
The pipet bulb costs $0.51 for one unit . The costs for four screws and four nuts would be
$0.48 purchased from Fastenal . A table with the specific costs of the components is
summarized below in Table 1.
As discussed prior, the NANOLYSER will not be entirely reusable. Though the purchase of the
ammeter will only have to be done once, the rest of the chip will have to be recycled after each
use. The team thought of a system where the NANOLYSER would be purchased in bulk by a
hospital or clinic. Once used in a checkup, the chip would be returned to the manufacturer, who
would properly recycle all related components. The nanowires have the potential to be reused in
Number of Parts Price Per Piece
Full Chip 12 5.00$
Ammeter 1 86.25$
Screws 4 0.44$
Nut 4 0.04$
TOTAL COST PER DEVICE
Costs of Parts
Table 1: The costs and number of individual parts for the NANOLYSER.
future chips, but would first have to be cleansed and retreated with the antibodies. Glass is
extremely recyclable and could be easily be recycled with virtually no environmental impact.
Proper disposal procedures would have to be followed for the PDMS. There are no known
detrimental effects on the environment or human anatomy caused by PDMS.
6.5. Improvements on Current Methods
Currently, to diagnose prostate cancer, there are two pre-tests, the PSA blood test and the DRE
exam, and one definitive test, the prostate biopsy. These tests are almost exclusively done in the
doctor’s office, with the exception of there being some at home blood tests being available. The
NANOLYSER is designed to be another option for the PSA blood test. It could be used as a part
of a yearly checkup, instead of having to have another complete blood test. It would give
immediate results, as opposed to having to send the sample to the lab. This is much faster, simpler,
and less painful than a blood test. Not only is it faster, but it can be much cheaper, as the only costs
are the cheap replaceable chips and the initial cost of the ammeter.
7. Summary and Conclusions
The goal of the design was to develop a device, known as a NANOLYSER, which could detect
the presence of a disease in only a single drop of blood. The NANOLYSER was designed to be
able to detect prostate cancer using microchannels, a silicon nanowire, and the chemical reaction
between a prostate cancer biomarker, PSA, and the antigen PSA-AB. The NANOLYSER functions
by introducing a drop of blood to the microchannels by the pressing of a finger onto microneedles.
As the blood flows through the channels, PSA in the blood adheres to the PSA-AB on the
nanowire, causing a change in the conductivity of the wire. Ultimately, this causes a change in the
current across the wire, proportional to the amount of PSA in the blood. This value of PSA can
then be determined.
7.1.1. Importance of Design
The design of the NANOLYSER offers a number of improvements over current methods of
prostate cancer diagnosis. Its features enable it to return immediate results, compared to current
tests that require the samples be sent to a lab and tested over a period of days. Though the device
is not entirely reusable, the ammeter can be used for a number of tests and is highly portable due
to its battery power. Current tests for prostate cancer are extremely invasive and oftentimes lead
to reluctance to be tested. The NANOLYSER operates with the prick of a finger and a droplet of
blood. The test created can be easily incorporated into a yearly checkup and does not require an
entire visit to complete. The cost would be minimal compared to costs for other exams. It is
simple to use and requires little prior knowledge, as it can be completed simply by plugging the
device into an ammeter and pricking the finger.
7.1.2. Future Work
The possibility exists to modify the NANOLYSER in such a way to add more diseases to the test.
By creating an array of nanowires, each coated with a specific antibody, the state of multiple
diseases could be tested simultaneously. Research is being performed into cheaper methods of
nanowire fabrication. Development of a device with a self-contained ammeter would be useful in
making the test applicable in a wider range of situations. Following this thought, a user-friendly
display that asks for age and ethnicity could improve the device. This would give a clearer
indication of a man’s prostate cancer diagnosis rather than a value for conductance. For such a
system to work, more research must be done on what constitutes a cancer-positive PSA level for
men of varying race and age.
The team would like to thank the OSU FEH Program for supplying any necessary resources
required for the study. The guidance of Dr. Deb Gryzbowski, Stefan Heglas, and all teaching
assistants was greatly appreciated and helped further the depth and quality of research. Dr. Jeffery
Chalmers also proved extremely helpful in m.the initial design and brainstorming process.
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Applications 2006 (2007): 2-1 – 2-4.
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spectral domain optical coherence tomography.” Microfluid Nanofluidics 13(2) (2012):
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Lee, Eun Kyung, Reiss, Jean, Lee, Yi-Kuen, Chung, Leland W. K., Huan, Jiaoti, Rettig,
Matthew, Seligson, David, Duraiswamy, Kumaran N., Shen, Clifton K.-F., and Tseng,
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 Dow Corning. (2015). Sylgard 184 Silicone Elastomer Kit. http://www.dowcorning.com/
 Fisher Scientific. (2015) Griffin Microammeter digital d.c. with battery.
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FIGURES AND TABLES
Figure A1: The top of the PDMS chip with grooves for nanowire.
Figure A2: The assembly view from the side.
Figure A3: The assembly view from the bottom.
Figure A4: The assembly view from the side.
Figure A5: The assembly view from the top.
Figure A6: The glass plate for the top of the NANOLYSER.
Figure A7: A top-down view of the nanowire in SolidWorks.
Figure A8: A detailed view of the bends in the nanowire.
1 0.8 0.0281
2 1.2 0.0422
3 1.3 0.0457
4 2 0.0703
5 2 0.0703
6 2.3 0.0809
7 2.6 0.0915
8 3 0.1055
9 3.2 0.1126
10 3.4 0.1196
11 4.1 0.1442
12 4.3 0.1512
13 4.5 0.1583
14 5.1 0.1794
15 5.6 0.197
16 5.7 0.2005
17 5.9 0.2075
18 6.2 0.2181
19 6.3 0.2216
20 7 0.2462
21 7.2 0.2533
Table A1: PSA levels and current values for the nanowire for 25 patients .
Figure A9: PSA levels corresponding to age for Caucasian, Asian, and African-American males.
EQUATIONS AND CALCULATIONS
𝑃𝑆𝐴 𝐿𝑒𝑣𝑒𝑙 (
) = 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 (𝜇𝐴) × 28.40909 (B1)
Sample Calculation for Equation B1
𝑃𝑆𝐴 𝐿𝑒𝑣𝑒𝑙 (
) = 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 (𝜇𝐴) × 28.40909 = 0.20 𝜇𝐴 × 28.40909 = 5.68