Smart contact lenses for continuous glucose monitoring (CGM) have great potential for huge clinical impact. To date, their development has been limited by challenges in accurate detection of glucose without hysteresis for tear glucose monitoring to track the blood glucose levels. Here, long-term robust CGM in diabetic rabbits is demonstrated by using bimetallic nanocatalysts immobilized in nanoporous hydrogels in smart contact lenses. After redox reaction of glucose oxidase, the nanocatalysts facilitate rapid decomposition of hydrogen peroxide and nanoparticle-mediated charge transfer with drastically improved diffusion via rapid swelling of nanoporous hydrogels. The ocular glucose sensors result in high sensitivity, fast response time, low detection limit, low hysteresis, and rapid sensor warming-up time. In diabetic rabbits, smart contact lens can detect tear glucose levels consistent with blood glucose levels measured by a glucometer and a CGM device, reflecting rapid concentration changes without hysteresis. The CGM in a human demonstrates the feasibility of smart contact lenses for further clinical applications.

Smart Contact Lenses Smart contact lenses for continuous glucose monitoring (CGM) have great potential for huge clinical impact in the field of diabetic diagnosis. In article number 2110536, Sei Kwang Hahn and co-workers describe bimetallic nanocatalysts immobilized in nanoporous hydrogels for long-term robust CGM in diabetic rabbits and humans to demonstrate clinical feasibility.

Smart contact lenses for continuous glucose monitoring (CGM) have great potential for huge clinical impact. To date, their development has been limited by challenges in accurate detection of glucose without hysteresis for tear glucose monitoring to track the blood glucose levels. Here, long-term robust CGM in diabetic rabbits is demonstrated by using bimetallic nanocatalysts immobilized in nanoporous hydrogels in smart contact lenses. After redox reaction of glucose oxidase, the nanocatalysts facilitate rapid decomposition of hydrogen peroxide and nanoparticle-mediated charge transfer with drastically improved diffusion via rapid swelling of nanoporous hydrogels. The ocular glucose sensors result in high sensitivity, fast response time, low detection limit, low hysteresis, and rapid sensor warming-up time. In diabetic rabbits, smart contact lens can detect tear glucose levels consistent with blood glucose levels measured by a glucometer and a CGM device, reflecting rapid concentration changes without hysteresis. The CGM in a human demonstrates the feasibility of smart contact lenses for further clinical applications.

Smart Contact Lenses Smart contact lenses for continuous glucose monitoring (CGM) have great potential for huge clinical impact in the field of diabetic diagnosis. In article number 2110536, Sei Kwang Hahn and co-workers describe bimetallic nanocatalysts immobilized in nanoporous hydrogels for long-term robust CGM in diabetic rabbits and humans to demonstrate clinical feasibility.

This article introduces a wireless power and data transfer (WPDT) system designed for low modulation index (MI) scenarios, specifically targeting smart contact lenses (SCLs). Conventional WPDT systems using load-shift keying (LSK) for implantable medical devices rely on proximity to ensure sufficient MI for wireless data transfer (WDT). However, SCL applications face a bottleneck in WDT due to a small-sized antenna and increased distance between the SCL and external reader (RX) unit, resulting in low MI. The proposed WPDT system overcomes this limitation by implementing an integrating receiver that employs a tradeoff in data rate to improve signal-to-noise ratio (SNR) under low MI conditions, thus supporting robust data communication at extended ranges. The proposed system utilizes two co-optimized chips—an RX and a transponder (TX)—in a full chain of a 433-MHz WPDT system. With an MI of 0.1%, the system achieves a bit error rate (BER) of less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 10^{-6}$</tex-math> </inline-formula>, demonstrating an improvement of more than 250 times compared to the best previously reported results. The designed ICs are fabricated using 0.18-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m CMOS technology. The SCL prototype incorporates a loop antenna, a resistive intraocular pressure (IOP) sensor, and the TX chip. The full system is validated both in vitro with 3-D-printed eye models and in vivo with a live rabbit. This work facilitates WPDT in compact biomedical devices such as SCL, addressing the inherent challenges of range limitations in low MI environments.

This paper presents a circuit technique that enables a selective amplification of the temperature coefficient of the sensing source, thereby mitigating the need for power-intensive readout schemes and simplifying the overall sensor architecture. Temperature coefficient amplifier introduces a negative proportional-to-absolute-temperature (PTAT) voltage, enabling an amplified gradient for both PTAT and complementary-to-absolute-temperature (CTAT) voltages within the usable temperature range, resulting in a reduced burden and precise temperature measurements with a low-complexity readout circuit. With a SAR-based conversion, implemented temperature sensor in 180 nm CMOS achieves a figure-of-merit of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$41 \text{fJ} \cdot \mathrm{K}^{2}$</tex> with a 22.2 mK resolution across <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-20^{\circ} \mathrm{C}$</tex> to 100° C while consuming 20.8nW. It shows a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3} \boldsymbol{\sigma}$</tex> inaccuracy of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\pm} \mathbf{1. 4} \boldsymbol{4}^{\boldsymbol{\circ}} \mathbf{C}$</tex> after a single-point trimming procedure.

This paper introduces a novel non-RC, leakage-based relaxation oscillator designed as a timer in ultra-low-power (ULP) applications. The proposed oscillator structure is created by stacking a source degeneration and a common-gate amplifier within a single branch, which effectively suppresses the temperature dependence of the leakage current. This temperature sensitivity is further mitigated through a two-point calibration method using a thermometer-driven nonlinear polynomial fitting process. The oscillator is designed to produce a 1.3 kHz output and is fabricated using a 180-nm CMOS process, occupying an active area of 0.108 mm² (including estimates for off-chip blocks). The oscillator consumes 1.43 nW, achieving a power efficiency of 1.1 nW/kHz. It maintains an average temperature sensitivity of 67.3 ppm/°C over a 0-to-90°C temperature range. The supply sensitivity of the oscillator is measured at 0.055%/V across a supply voltage range of 1.1 V to 1.8 V, and the measured Allan deviation floor is 20 ppm.