In-Body Electromagnetic Sensor Combined with AI-Enhanced Electrocardiography for Pacemaker Working Status Telemonitoring

This paper describes the design and implementation of an in-body electromagnetic sensor for patients with implanted pacemakers. The sensor can either be mounted on myocardial tissue and monitor the electrocardiography (ECG) with contact electrodes or implanted under the skin and monitor the ECG with coaxial leads. A 16-bit high-resolution analog front-end (AFE) and an energy-efficient 32-bit CPU are used for instantaneous ECG recording. Wireless data transmission between the sensor and clinician’s computer is achieved by an embedded low-power Bluetooth transmitter. In order to automatically recognize the working status of the pacemaker and alarm the episodes of arrhythmias caused by pacemaker malfunctions, pacing mode classification and fault diagnosis on the recorded ECG were achieved based on an AI algorithm, i.e., a resource allocation network (RAN). A prototype of the sensor was implemented on a human torso, and the in vitro test results prove that the sensor can work properly for the 1-4-meter transmission range.

A Demodulation Circuit For Analog Front End Of Passive Tag Chip

The demodulation circuit designed in this paper is suitable for the analog front end of passive UHF RFID tag chip, which can handle ASK signals with large changes in amplitude, modulation depth and signal frequency. Its performance meets the requirements of standards ISO/IEC 18000-6C and GB/T 29768-2013. Envelope detection circuit and limiter circuit are simple in structure and do not consume power. The comparison reference voltage is taken according to the average value of the envelope high and low levels, and is less affected by the dynamic changes of the input signal. Changing the width-to-length ratio of the MOSFETs in the feedback path of the comparator can adjust the hysteresis, with strong noise suppression and controllable sensitivity. The demodulator is implemented with TSMC 0.18 μm standard CMOS process. The simulation results show that the ASK signal modulation depth that the demodulator can handle is as low as 30%, and the maximum pulse width demodulation error is only 0.43%.