A 0.24 mmHg (1σ) Resolution Half-Bridge-to-Digital Converter with RC Delay-Based Pressure Sensing and Energy-Efficient Bit-Level Oversampling Techniques for Implantable Miniature Systems

Abstract

Glaucoma is a disease that can cause intraocular pressure (IOP) to rise, damaging the optic nerve and potentially causing irreversible blindness. For better postoperative treatment and management of glaucoma patients, frequent and accurate IOP monitoring is required. In response to such needs, there is increasing interest in developing an implantable system for continuous bio-monitoring to perform diagnosis without requiring the patient to visit a hospital. However, the design of an implantable system is challenging since both the precision requirement and energy budget need to be met within a stringent volume constraint. High energy consumption per measurement can potentially burden battery-operated miniature systems [1] or implanted systems with tiny coils for limited power transmission [2]. For minimum invasiveness and damage to the eyes, a pressure sensor with an RC delay-based half-Wheatstone-bridge-to-digital converter (HBDC) is proposed to enable implantable pressure monitoring systems. For such implantable systems, minimizing the volume and height of the pressure sensor is critical to securely place the sensor in a limited space without damaging eyes. © 2022 IEEE.