We demonstrate smart contact lenses for noninvasive and continuous diabetic diagnosis and diabetic retinopathy therapy.

This article presents a controller IC for smart contact lens (SCL). For wireless telemetry, we propose a transmitter supporting dual-mode operations with a single external loop antenna. In the wireless-powered backscattering load-shift keying (LSK) mode, the transmitter is configured to use the antenna as an L for magnetic resonance coupling. The transmitter switches its configuration to be an active LC oscillator circuit in the RF-radiated transmission mode. To suppress the average power consumption, a 0.2% duty cycling is applied with a controlled timing schedule while minimizing static power consumption in the sleep mode. To reduce the effect of instantaneous discharging, the period of data transmission is shortened by transmitting data with a higher rate. The designed IC is fabricated using 0.18-μm CMOS. For in vitro verifications in both modes, an SCL is implemented by integrating the IC, a glucose sensor, a thin-film battery, a loop antenna, and a supply-regulating capacitor. The IC achieves a power consumption of 143 nW with an input dynamic range of 89 dB.

The human eye has been considered to be a promising platform for real-time diagnosis of various biomarkers in tears. The smart contact lens (SCL), as a device which directly accesses surface of human eye, is a miniaturized autonomous system integrating all the required functions on the surface of a thin film. This article presents the first implementation of a set of radio including a wake-up receiver required for SCL. The system performs RF transmission upon wake-up call using a single loop antenna. The receiver path has a baseline-tracking offset control loop to successfully detect wakeup signal in the standby state under noisy environment. The operating frequencies for uplink and downlink are 346 and 433 MHz, respectively. A magnetic-coupled wireless charging of an OFF-chip battery is also provided through the same loop antenna. The designed IC is fabricated using 0.18- μm CMOS process, consuming a power of 2.5 nW in wakeup-ready standby state. The IC is also verified with a loop antenna and a thin-film battery integrated on a substrate of SCL.