A CMOS process compatible charge-modulated FGFET based ion sensor for integration into Organ-on-Chip platforms

A CMOS process compatible charge-modulated FGFET based ion sensor for integration into Organ-on-Chip platforms

Sinha, Rajarshi (TU Delft Electrical Engineering, Mathematics and Computer Science)

Sarro, Pasqualina M (mentor)
Quiros Solano, W.F. (graduation committee)
French, P.J. (graduation committee)
Mastrangeli, M. (graduation committee)

Delft University of Technology

Electrical Engineering

2018-11-28

Drug development is an entire area of research that partly exploits the developments from biomedical research. Understanding the diseases that affect humanity fatally is critical to our existence. Researchers have studied various molecules and genetic compounds that are responsible for the proliferation of these diseases in the human body. For this purpose, by-far, animal testing has been used most extensively in drug development. Several human physiological models have also been developed to test the efficacy of new therapies. How-ever, it is very difficult to accurately model human diseases in-vitro which has led to failure of several potential drugs.

Consequentially, Organ-on-Chip (OOC) platforms have been developed to serve this purpose. They are specially designed to mimic human organs on a microlevel. Within such controlled microenvironments, biological and electrochemical cues can be well monitored. Stretchable Microelectrode Arrays (SMEA) are commonly used membrane based OOC platforms with suspended electrodes on the stretchable membrane, that are responsible for electrical stimulation. Additionally, several configurations of ion sensors such as Organic Electrochemical Transistors (OECT), Organic Thin-Film Transistors (OTFT) and so on have also been used for integration into OOCs. However, most such devices make use of reference electrodes for biasing the transistors that do not provide for easy integration into standard CMOS fabrication technology. Further, the reference electrodes also can disintegrate and affect the electrolyte over extended periods of biasing.

In this thesis, a reference electrode-less floating gate ion sensor has been proposed that can be realized with low-cost standard CMOS technology. The Charge-modulated Floating Gate FET (FGFET) has been designed, microfabricated and electrically characterized. The device makes use of a standard transistor design with a built-in control capacitor that acts as the reference electrode and sets the working point of the transistor. The gate elec-trodes are extended on an active sensing area that is bound by a glass cylinder containing the electrolyte. This delimits the rest of the device from the ionic solution. The change in current output of the device in response to ionic charge variation with different concentrations of the electrolyte was tested and the results have been shown here-in. The device shows a sensitivity of 0.4 ampere per molar concentration of electrolyte or 0.4A/M, which is very good for research purposes as was intended in this study. Further, the sensing area is fabricated as a free-standing PDMS membrane with suspended gate electrode extensions, which further validates the potential of the Charge-modulated FGFET to be integrated into stretchable OOC platforms. The easy microfabrication process and good sensitivity of the device presented in this work is an important step towards the integration of ion sensors for OOC applications.

Organ-on-chip
Ion sensor
Reference electrode
PDMS

http://resolver.tudelft.nl/uuid:ffe4d7ab-2b05-4624-8f51-2e149e5052ab

2021-11-28

Student theses

master thesis

© 2018 Rajarshi Sinha