Research and Development of Enhancing Electrochemical Impedance Biosensor Sensitivity by Thermophoresis
Date Issued
2015
Date
2015
Author(s)
Liu, Ling-Ya
Abstract
With the advancement of science and technology, the focus of health care has gradually turned from patient treatment and care towards health enhancement and diseases prevention. Interferon-gamma release assays (IGRA) was adopted in this research to serve as an alternative of tuberculin skin test (TST) for the diagnosis of latent tuberculosis infection (LTBI) due to its high efficiency in identifying the infection of LTBI. Electrochemical impedance spectroscopy (EIS) biosensor was used to develop point-of-care (PoC) application platforms due to its characteristics such as low cost, simple instrumentation, fast response time, etc. To detect the spontaneous interaction between receptor (antibody) and analyte (antigen) in traditional biochips, specific binding variation was transformed into electrical signal which represented the detection signal of biochips. Only the analyte near the electrode surface has the opportunity to bind with the antibody, which not only leads to sample waste but also consumes precious testing time. All of which will make traditional biochips face limitations such as lower signal/noise ratio (S/N Ratio) in low analyte concentrations and long testing time, etc. To improve the sensitivity of EIS and the S/N Ratio of biochips, thermophoresis was adopted in this thesis to move the analyte to locations near the electrode surface. Thermophoresis is a phenomenon about the migration of particles with a temperature gradient, which was done by adding Polyethylene glycols (PEG) Polymer to drive molecule (antigen) motions through temperature gradient towards the EIS electrodes in order to increase the binding rate. By observing the fluorescence from the capture probes bound to the antigens and the EIS results, Interferon-gamma (IFN-γ) was found to indeed accumulate near the electrode as lower concentration and improved detection limit (LOD) were observed. In this thesis, we developed a microfluidic biochip system which can execute binding steps, accumulate antigen by steady temperature gradient and enhance the sensitivity of electrochemical measurement while reducing the binding time.
Subjects
thermophoresis
EIS
biochip
SDGs
Type
thesis
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