An integrated impedance biosensor array
Abstract/Contents
- Abstract
- Affinity biosensors are important tools for detecting DNA, proteins, cells, and other biomedical analytes. Although optical readout is prevalent, impedance readout is promising for many applications due to lower cost, reduced system size, and label-free operation. Impedance biosensors detect the binding of a target biomolecule to an immobilized probe by quantifying changes in the the electrode-electrolyte interface impedance. Impedance biosensors traditionally use bulky and expensive instruments to monitor the impedance of a single electrode. We describe miniaturized and inexpensive readout circuitry for an array of such sensors. By using a sensor array, multiple analytes can be simultaneously detected and limitations inherent to individual sensors can be mitigated. Reducing the size and cost of the measurement system enables new applications. We present a measurement system for a 6x6 array of impedance biosensors built from off-the-shelf components. Experimental results with DNA probe-target pairs confirm others' reports that changes in the interface impedance can signify binding. Other experiments with proteins demonstrate that changes in the nonlinearity of the I-V relationship can also indicate probe-target binding. We show that the impedance and the nonlinearity can be quantified simultaneously by superimposing a large-amplitude tone on the impedance-measurement tone and analyzing the resulting intermodulation tones. We conclude by describing an integrated array of measurement circuits implemented in 0.18 um CMOS. Each of the 36 measurement pixels contains an impedance-measuring circuit plus tone cancellation circuitry, which enables simultaneous nonlinearity measurement. To prevent the large-amplitude excitation from saturating the amplifier output, a per-pixel digital feedback loop injects an appropriate cancelling current at the amplifier input. Impedance changes of 0.2% can be detected using the integrated measurement circuit. Each pixel occupies 0.14 mm2 and consumes 1.9 mW.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Daniels, Jonathan Spencer |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering |
| Primary advisor | Lee, Thomas |
| Thesis advisor | Lee, Thomas |
| Thesis advisor | Kenny, Thomas William |
| Thesis advisor | Pourmand, Nader, 1965- |
| Advisor | Kenny, Thomas William |
| Advisor | Pourmand, Nader, 1965- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jonathan S. Daniels. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Ph.D. Stanford University 2010 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Jonathan Spencer Daniels
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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