Hydrogen ion sensing based methods are widely used in various applications, such as DNA sequencing, food screening, antibiotic study etc. At the forefront of these, ion-sensitive field effect transistor (ISFET) shows great promises. This thesis explores methods to improve ISFET sensor performance using novel front-end topologies and readout system in CMOS technology in the target of cost-effective and robust hydrogen ion sensing results.

Charge trapped in the floating gate of CMOS ISFET induces low pixel yield and the requirement of complex calibration methods. This problem is solved by using a novel front-end and auto-compensation system proposed by this work. A full pixel yield and state-of-the-art sensing resolution are achieved.

This thesis proposes a multi-modal sensor fea...[ Read more ]

Hydrogen ion sensing based methods are widely used in various applications, such as DNA sequencing, food screening, antibiotic study etc. At the forefront of these, ion-sensitive field effect transistor (ISFET) shows great promises. This thesis explores methods to improve ISFET sensor performance using novel front-end topologies and readout system in CMOS technology in the target of cost-effective and robust hydrogen ion sensing results.

Charge trapped in the floating gate of CMOS ISFET induces low pixel yield and the requirement of complex calibration methods. This problem is solved by using a novel front-end and auto-compensation system proposed by this work. A full pixel yield and state-of-the-art sensing resolution are achieved.

This thesis proposes a multi-modal sensor featuring temperature, hydrogen ion and optical sensing capabilities to extract multiple information. The multi-modal functionalities are enabled by an inverter-based amplifier and a reset switch with low-leakage current. Multiple sensing information provided by this sensing system promise a more robust and reliable result than single sensor alone.

This thesis also examines high density, high sensitive and high frame rate sensing system for high accuracy and high throughput hydrogen ion imaging. These features are enabled by a novel ion-to-current-to-voltage 2-transistor (2T) and a capacitive transimpedance instrumentation amplifier. A column SAR-Single Slope ADC is employed in the optimization of frame rate, chip area and system power consumption. The state-of-the-art sensitivity and frame rate are achieved in this work.

Finally, a real-time CMOS multi-sensor platform consists of temperature, hydrogen ion, optical and micro-heater is proposed for robust hydrogen ion sensing based biomedical applications.