WULPUS PRO: Multi-mode Ultra-Low-Power Wearable Ultrasound and Array Imaging with CMUT Support

Wearable ultrasound has emerged as a key technology for continuous monitoring of physiological processes such as muscle dynamics, bladder volume, and cardiovascular activity. Existing fully-wearable ultra-low-power platforms are limited to shallow, low-channel A-mode sensing, while large-channel count (>8) multi-mode systems are too large and power-hungry for true wearability. To bridge this gap, we present WULPUS PRO, a novel runtime-programmable wearable ultrasound acquisition platform with an ultra-compact size of 39 × 21 × 6mm and low weight (5 g) that integrates 30 V excitation, 16 time-multiplexed channels, a low-noise receive front-end with up to 70dB gain (14MHz amplification chain bandwidth), time-gain compensation, and SNR of 45 dB. This enables deep-tissue echo acquisition using transducers with central frequency up to 2.2MHz in RF-sampling mode and up to 8MHz in envelope-detection mode. We demonstrate for the first time B-mode imaging in a 16-channel ultra-low-power wearable, achieving submillimeter axial and millimeter-scale lateral resolution in phantom experiments while operating within only 40 mW power budget at 50 Hz Pulse Repetition Frequency (PRF) and under 60 mW at 300 Hz PRF. Furthermore, WULPUS PRO demonstrates support, for the first time, of both piezoelectric and Capacitive Micromachined Ultrasonic transducers (CMUTs), enabling tight integration with emerging skin-conformal polymer-based CMUT arrays. WULPUS PRO is designed as a host-agnostic acquisition front-end, exposing standard data and power interfaces for integration with different wearable host platforms (e.g., BLE- or WiFi-based). We demonstrate wireless data transmission with external Bluetooth Low Energy and Wi-Fi modules, and we project multi-day BLE operation (1-2 days at 50 Hz PRF) and multi-hour Wi-Fi streaming (> 3 h at 300 Hz PRF) for a 300mAh (6.4 g) Li-Po cell. Thus, WULPUS PRO establishes a new class of wearable ultrasound acquisition platforms for continuous, fully programmable, B-mode-enabled, ultra-low-power and low-noise sensing.