PhD Thesis Defense

Portable and point-of-care medical devices are becoming an essential part of today's medical technology. An affordable personal device that can diagnose and monitor a medical condition in real time will improve the patient's life quality in many ways. Additionally, by autonomously providing suitable treatment, a universal healthcare device can be accessible to most of the population at a low cost. Despite considerable efforts and great outcomes, most of the prior arts in realizing these devices have limitations that hinder their widespread use in portable applications.

In the first part of this dissertation, we introduce the "Silicon-Cell" system comprising a fully integrated fluorescence sensor. The single-chip solution in a 65nm standard CMOS process includes bandpass optical filters, photodiodes, and processing circuitry. The metal/dielectric layers in CMOS are employed to implement low-loss cavity-type optical filters, achieving a bandpass response at 600/700nm range suitable to work with fluorescent proteins. The sensitivity of the sensor is further improved by innovative circuit design techniques, resulting in a minimum measured current of 1.05fA with SNR >18dB. The sensor can measure the statics/dynamics of the fluorescence signal as well as the growth of living E. coli bacterial cells. Using a differential design and layout, the sensor can distinguish two biochemical signals by measuring two fluorescent proteins encoded in a single bacterial strain. Furthermore, a proof of concept is demonstrated to establish bidirectional communication between living cells and the CMOS chip, using a fluorescent protein regulated by an optogenetic control.

In the second part of this dissertation, we describe a fully integrated high-bandwidth optical receiver for RF-over-free-space optics (RoFSO). This work is motivated by the availability of the wide, unregulated bandwidth at the optical frequencies and the lower cost and setup time of the free space link. We present novel solutions at the system and circuit level to make the receiver adaptive and resilient to atmospheric distortions. The chip is designed and implemented in a 28nm CMOS process, and it is shown to achieve a measured gain of 58dB and bandwidth of 18GHz. For a proof-of-concept demonstration, an 8Gbps non-coherent DPSK signal is transmitted, resulting in a BER of 1 × 10-4 for a minimum received power of -30dBm.