A small form-factor, lightweight wireless capsule endoscope (WCE) system with body channel communication (BCC) transceiver ICs is proposed for VGA-resolution image transferring and capsule localization. The transceiver ICs are composed of capsule chip and receiver chip, implemented in a 65-nm CMOS process. In the capsule side, the proposed system provides 360° image capturing through four-camera integration to reduce the miss rate. Also, a dual-band pulse-shaping BCC transmitter is proposed to enable low-power (<1 mW), high-speed (80 Mb/s) image transmission. In the receiver side, contact attenuation compensated-received signal strength indicator (CAC-RSSI) is proposed to increase the capsule localization accuracy. The external system is composed of eight-receiver nodes that allow signal demodulation and localization of the capsule. To reduce transceiver payload and system power consumption, image encoder is implemented in the capsule. The transceiver IC is integrated into the capsule system and verified with body mimicking phantom. The proposed system satisfies compatibility with medical grade diagnosis by operating longer than 8 h with 4 fps and 12 h with 2 fps with conventional two silver oxide 55-mA· h coin batteries. The tested localization accuracy shows less than sub-centimeter range.

In this article, a body channel communication (BCC) transceiver (TRX) and low-power receiver (RX) that can cover wide applications are proposed. The IEEE 802.15.6 human body communication (HBC) physical layer (PHY) standard and high-speed data transmission are supported simultaneously with a single chip. First, the sinusoidal-modulated transmitter is proposed for the standard mode TRX, and it can reduce filtering power overhead 35%. Second, high-speed TRX is proposed that can support dual-band QPSK modulation to increase system data rate and bandwidth efficiency. Third, on-chip RC duplexer is proposed for full-duplex function in communication. Also, for the low-power RX, a wireless power transfer (WPT)-based wake-up receiver (WuRX) and a higher energy efficiency main RX is integrated into RX chip. The main HBC RX demodulates both ASK and frequency-shift keying (FSK) information with a sharing oscillator (OSC) with 31-μW low-power consumption. The TRX and RX are implemented in 65-nm CMOS process.

An ultra-low-power duty controlled received signal strength indicator (RSSI) is implemented for human body communication (HBC) in 180 nm CMOS technology under 1.5 V supply. The proposed RSSI adopted 3 following key features for low-power consumption; 1) current reusing technique (CR-RSSI) with replica bias circuit and calibration unit, 2) duty controller, and 3) reconfigurable gm-boosting LNA. The CR-RSSI utilizes stacked amplifier-rectifier-cell (AR-cell) to reuse the supply current of each blocks. As a result, the power consumption becomes 540 μW with +/-2 dB accuracy and 75 dB dynamic range. The replica bias circuit and calibration unit are adopted to increase the reliability of CR-RSSI. In addition, the duty controller turns off the RSSI when it is not required, and this function leads 70% power reduction. At last, the gm-boosting reconfigurable LNA can adaptively vary its noise and linearity performance with respect to input signal strength. Fro current reusing technique m this feature, we achieve 62% power reduction in the LNA. Thanks to these schemes, compared to the previous works, we can save 70% of power in RSSI and LNA.

This article presents a low-power, battery-less biopotential-recording integrated circuit (IC) designed for implantable leadless cardiac monitoring applications, addressing full autonomy based on wireless energy harvesting and closed-loop control. A key technical feature is the closed-loop capability with integration of a dual-band radio frequency (RF) energy harvester and communication system utilizing industrial, scientific, and medical (ISM) bands at 40.68 MHz for downlink and 915 MHz for uplink, ensuring efficient wireless power transfer and robust bidirectional data communication. The RF harvester achieves a peak conversion efficiency exceeding 40%, a critical design challenge in maintaining consistent performance under variable power conditions. Also, the proposed IC overcomes the need for a local oscillator (LO) by utilizing an externally provided clock, reducing system complexity and power consumption. Operating with a clock frequency of 100 kHz, the IC consumes only $8.8~\mu $ W, a major achievement in energy efficiency for wireless, battery-less systems. Fabricated in a 180-nm complementary metaloxidesemiconductor (CMOS) process, the IC successfully demonstrates cardiac signal measurement and heart rate (HR) extraction under a fully battery-less environment with air medium, providing a promising solution for next-generation leadless cardiac monitoring systems.

A capsule endoscope system that can support wide visualization field image capturing and location tracking capability is proposed. The body channel communication (BCC) transceiver integrated circuit (IC) and 4-camera module is integrated in the proposed capsule endoscope. To support 4-camera image transmission, BCC transceiver provide high speed data rate with low-power. With cross-coupled camera module, 360-degree of image capturing is supported. For the accurate (subem range) capsule localization, contact attenuation compensation scheme is proposed. The system is integrated on the rigid flexible printed circuit board (PCB) to reduce system form factor. The proposed endoscope system operates longer than 8 hours with 4fps and 12 hours with 2fps with conventional small size coin battery and verified through human mimicking phantom.