CMOS Single Photon Avalanche Photodiodes and Digital Control Interface for Lab-on-Chip DNA Analysis Systems

Abstract

BioMEMS focuses on microelectromechanical systems for biological, or biomedical applications. Combining BioMEMS and CMOS allows highly integrated, complex analysis devices to be realized. One application of particular interest, is medical diagnostic testing. The overall goal of the multi-disciplinary, multi-institutional project to which this research contributes, is a single-use, small, portable, low power, Lab-on-Chip genetic analysis device. Combining all of the electronic structures, including instrumentation, communication, high voltage generation, and optoelectronics onto one CMOS die, and vertically integrating the BioMEMS structures, including heaters, chambers, separation channels, electrostatic valves, and magnetic separation, allows for wafer manufacturing of both CMOS and BioMEMS structures at the same time. Such a device could revolutionize healthcare, by providing inexpensive, fast, point-of-care diagnostics, even in remote regions, without any of the infrastructure currently required to perform such testing. This work focuses on CMOS Single Photon Avalanche Photodiodes (SPAPDs) for optical detection of fluorescently labeled molecules, such as DNA, suitable for integration in a CMOS - BioMEMS Lab on Chip. The advantages of SPAPDs versus conventional photodiode detectors are higher speed, greater sensitivity, and direct digital output. The digital pulses produced by SPAPDs can eliminate the need for an analog to digital converter for optical detection. The the combination of higher speed and greater sensitivity should allow fluorescence lifetime detection to be achieved, eliminating the need for problematic optical filters. In addition to the development of SPAPDs, a new SPI-based digital interface was developed for the Lab-on-Chip system. A new modular, addressable register-based interface was developed, allowing easy changes or additions to any on-chip subsystems.