Miniaturized biosensor for point-of-care total protein measurement
Abstract/Contents
- Abstract
- Point-of-care test is defined as medical diagnostic testing at the time and place of patient care. Compared to conventional medical lab exams, point-of-care tests are accessible at home and produce near real-time test results at much lower cost. We have demonstrated a point-of-care biosensor for measurement of total protein in human serum and urine, with applications to clinical testing of diabetes as well as kidney and liver diseases, among other medical conditions. The first part of the thesis covers the design principles of the sensor, which is a miniaturized optoelectronic device comprising of a VCSEL, a PIN photodetector and emission filter bonded on the same chip. The VCSEL (vertical cavity surface emitting laser) acts as the light source and its vertical and low divergence emission enables miniaturization at low cost. The integrated photodetector and emission filter further lower the footprint of the device. The sensor operates in the NIR (Near Infra-Red) region ideal for biomedical sensing. It induces and records a fluorescence signal from the biological sample, yielding photocurrent proportional to fluorescence intensity. The second part of the thesis covers the development of a simplified assay preparation using a bare fluorescent dye, Cy5.5 that exhibits increased fluorescence in the presence of protein, with signal change linearly proportional to protein concentration. We harnessed this 'protein-induced fluorescence' phenomenon to measure the concentration of total proteins present in biological fluid samples, such as human serum or urine. These samples were analyzed using our VCSEL sensor, which demonstrated a highly linear correlation between protein concentration and photocurrent (resulting from fluorescence emission) within a dynamic range much larger than the clinical standard. The VCSEL sensor demonstrated greater accuracy than large-scale fluorescence imaging systems like the spectrophotometer and the IVIS that are deemed "gold standards" commonly used in biomedical applications. Compared to other conventional methods for detecting proteins, our point-of-care device presents a greatly simplified, inexpensive, real time and sensitive sensing method requiring a very small sample volume (3 drops~150µl). With thorough analysis of the results across wide range of protein concentrations in human serum and urine, we concluded the efficacy of the proposed sensing method using the VCSEL biosensor and PIFE assay with promising future applications in multiplex detection platforms like smart toilets or personalized health-monitoring tools for patients with limited access to medical labs.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Mahzabeen, Fariah |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Fan, Shanhui, 1972- |
| Thesis advisor | Gambhir, Sanjiv Sam |
| Thesis advisor | Vermesh, Ophir |
| Advisor | Fan, Shanhui, 1972- |
| Advisor | Gambhir, Sanjiv Sam |
| Advisor | Vermesh, Ophir |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Fariah Mahzabeen. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Fariah Mahzabeen
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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