A Wireless Multimodal Physiological Monitoring ASIC for Animal Health Monitoring Injectable Devices.

Area of Science:

• Biomedical Engineering
• Implantable Devices
• Animal Health Monitoring

Background:

• Wearable animal health monitors are limited by motion artifacts and signal quality.
• Injectable devices offer superior signal-to-noise ratio (SNR) and immunity to movement.
• There is a need for integrated, low-power wireless solutions for in-vivo physiological monitoring in animals.

Purpose of the Study:

• To develop and evaluate a wireless Application-Specific Integrated Circuit (ASIC) for injectable animal health monitoring.
• To integrate multiple physiological sensing modalities into a single microchip implant.
• To demonstrate the feasibility of wireless power and data telemetry for implantable biosensors.

Main Methods:

• Fabrication of a CMOS 180 nm ASIC with integrated temperature, electrocardiography (ECG), and photoplethysmography (PPG) sensors.
• Design of low-power analog front-ends (AFEs) for each sensor modality, including a switched-capacitor (SC) LED driver and photodiode AFE for PPG.
• Implementation of a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) and a backscatter-based data telemetry system.
• In-vivo evaluation of the ASIC's functionality and performance in an animal model.

Main Results:

• The ASIC successfully integrated temperature, ECG, and PPG sensing capabilities within an injectable microchip form factor.
• The low-power design achieved an average DC power consumption of 155.3 µW, enabling wireless inductive powering.
• The ECG AFE provided adjustable gain (45-79 dB) and a low cut-off frequency (0.3 Hz).
• The PPG sensor utilized an energy-efficient SC LED driver and a programmable transimpedance gain AFE.
• The temperature sensor achieved 0.02 °C inaccuracy within a 27-47 °C range.
• The SAR ADC demonstrated a 57.5 dB signal-to-noise-and-distortion ratio (SNDR) within a 1 kHz bandwidth.
• Successful in-vivo experiments validated the ASIC's overall performance for physiological signal acquisition and wireless data transmission.

Conclusions:

• The developed wireless ASIC represents a significant advancement for injectable animal health monitoring systems.
• The integrated multi-modal sensing capabilities and low-power wireless operation pave the way for continuous, non-invasive in-vivo health assessment in animals.
• This technology has the potential to improve early disease detection and personalized veterinary care through enhanced physiological data acquisition.