A 1 mm x 1 mm CGM System on Die Achieving 1.65-nA/mM In Vivo Resolution and 0-40-mM/L Detection Range With Delta Sigma Backscatter Technique

Diabetes has become a leading cause of death and disability all over the world. Continuous glucose monitoring (CGM) based on wireless power transfer (WPT) and backscatter communication enables wireless real-time telemetry to control glycemic levels in a long term. However, conventional backscatter techniques in CGM systems converted the sensing current into a bit stream or a frequency signal to switch the antenna, leading to two drawbacks: 1) Large power-harvesting antennas are required to complement the power loss in data converting and antenna switching and 2) Both the resolution and detection range are limited even with a high-performance glucose sensor. In this work, we propose a delta sigma backscatter technique to demonstrate a system on die (SoD) within a 1 x 1-mm on-chip antenna. Implemented in the 65-nm CMOS process, the proposed SoD achieves a telemetry error less than 0.25% with little impact on WPT, as well as a wide detection range of 0-40 mM/L. In vivo experimental results show that the CGM SoD realizes a resolution of 1.65 nA/mM.

Automated summary

Diabetes has become a major cause of death and disability worldwide. Continuous glucose monitoring (CGM) based on wireless power transfer (WPT) and backscatter communication allows for real-time wireless telemetry to control glycemic levels in the long term. This study proposes a delta sigma backscatter technique for CGM, which achieves high-precision glucose monitoring over a wide range of concentrations using a small on-chip antenna.