Research and development of label-free electrochemical impedance bio-affinity metrology system
Date Issued
2012
Date
2012
Author(s)
Li, Kai-Chiang
Abstract
With the societal advancement, living style improvement, and medical technologies development, the average human life span has increased significantly. These changes also signal the coming of aging society. The body function and metabolism of the elders are known to be weaker than grownups and children. In addition, the elders are prone to many chronic diseases or cancer. All of which indicate that home care and health care services of elders are becoming ever more important. The biosensors developed with a goal to pursue point of care are becoming more widely available. This thesis focuses on developing a label-free electrochemical biosensor that fits the point-of-care application needs.
Taking novel conducting linker as the starting point and integrating it into the corresponding chip equipped with microfluidic system developed by the NTU BioMEMS team, this thesis further utilized electrochemical impedance spectroscopy to develop a complete bio-affinity metrology system. With the adoption of the innovative conducting linker developed within the team, the signal to noise ratio of traditional electrochemical bio-affinity sensor was greatly improved such that the difficulty associated with the design and the implementation cost of the interfacing circuits were minimized. In the signal processing part, we used a DAQ card (data acquisition card) to digitize the analog signal. We then employed LabVIEW to establish the lock-in amplifier for noise elimination so as to lead to precise impedance measurement. Besides, we integrated driving circuits of syringe pump into an electro-board, which was controlled by using LabVIEW to design the HMI (Human Machine Interface). Our biochips were made by micro machining process with glass as the substrate and Au as the working electrode. We also designed a locking mechanism to ease the biochips replacement and to reduce the overall system volume.
Our study measures C-reactive protein, S-100 protein, successfully. These results verified the feasibility and sensitivity of our system, which was found to meet the lowest detected limits currently required by the hospital. We found that protein with bigger molecular weight may result in bigger ΔRct changes.
Subjects
Impedance biosensor
Label-free
biochip
SDGs
Type
thesis
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