Electrode-based integrated bio-sensing system

Abstract

Quality healthcare is one of the most important aspects in the modern society. As the crisis of population aging is looming, together with scarce public health resources, there is an emerging demand for novel point-of-care diagnostic devices. Commercial and academic attempts contributing to this cause are ubiquitous. However, a persistent thrust in the development of mass-adoption ready point-of-care diagnostic devices is still required, especially in the power, size, and sensitivity departments. Traditional schemes used in laboratories may have intrinsic requirements that limit their feasibilities to be deployed in point-of-care diagnostic devices. Novel, innovative ideas are much needed. In close accordance with the requirements of point-of-care, this thesis focused on advancing relevant technologies for point-of-care diagnostic testing. Two major works have been accomplished. The first work focused on improving the sensitivity of point-of-care impedimetric sensing schemes. The second work focused on improving magnetophoretic-based signal enhancement schemes. The first work provides a comprehensive study of the impedance characteristic of silver/silver chloride electrodes, so that they can be optimally designed to perform as an impedance sensor. A novel fabrication protocol is introduced to optimally fabricate such electrodes for impedance sensing. Pioneering models are established to estimate the impedance-related circuit parameters of the electrodes based on their morphological characteristics and electrochemical processes. The models are verified with impedance measurements from micro electrodes. The second work presents an optimally fabricated soft ferromagnetic structure enhanced magnetophoretic microfluidic device for the trapping of magnetic particles under continuous fluid flows. Rapid and cleanroom-less fabrication of the magnetic module is achieved. The geometry of the soft ferromagnetic structure is scrupulously designed to achieve the best performance. A novel algorithm is tailor made to estimate the performance of the device. Lastly, the magnetic module is integrated into an electrochemical device to demonstrate its signal enhancement capabilities.

Date of Award	2022
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	George Jie YUAN (Supervisor)