A Study on Ultra-low-power Wireless Sensor Interface IC Systems for Smart Contact Lens Application

Abstract

Human eye, with cornea exposed to be accessible, has been considered as a promising healthcare platform providing desirable environments for diagnosis of human health, monitoring of eye-condition, disease treatment through drug delivery and auxiliary vision-aids. The smart contact lens (SCL) has been extensively researched to fully integrate an antenna, a sensor, a thin-film battery and a controller IC on a contact lens. The IC needs to provide all the required functions as an autonomous controller. This thesis presents works on IC implementation as a biosensing platform (Chapter 1) and a radio platform for the SCL (Chapter 2). The first IC in Chapter 1 supports a dual-mode telemetry with wireless-powered loadshift keying and RF transmission using a single loop antenna [A.1]. The IC is driven by duty-cycling with an on-chip timer, achieving a power consumption of 143nW with an input dynamic range of 89dB. The second IC in Chapter 2 supports a wakeup receiver (WuRx) working with a bidirectional wireless data communication and wireless charging using a single loop antenna. It provides all the required radio schemes to be applicable to SCL, achieving a power consumption of 2.5nW. The designed ICs are fabricated using 0.18-μm CMOS process. For in vitro verification, the first IC is applied to a glucose monitoring SCL. Functionalities of the second IC is also tested on a thin-film substrate of SCL.