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

Wearable ultrasound enables 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 larger multi-mode systems are too bulky and power-hungry for true wearability. We present WULPUS PRO, a runtime-programmable wearable ultrasound acquisition platform measuring $39\times21\times6 \mathrm{mm}$ and weighing $5 \mathrm{g}$. It integrates $30 \mathrm{V}$ excitation, 16 time-multiplexed channels, a low-noise receive front-end with up to $70 \mathrm{dB}$ gain, $9.9 \mathrm{MHz}$ bandwidth, time-gain compensation, and $32 \mathrm{dB}$ SNR. The platform supports deep-tissue echo acquisition up to $2.2 \mathrm{MHz}$ in RF-sampling mode and $8 \mathrm{MHz}$ in envelope-detection mode. We demonstrate B-mode imaging in a 16-channel ultra-low-power wearable with sub-millimeter axial and millimeter-scale lateral resolution in phantom experiments, while consuming $40 \mathrm{mW}$ at $50 \mathrm{Hz}$ PRF and under $60 \mathrm{mW}$ at $300 \mathrm{Hz}$ PRF. WULPUS PRO supports both piezoelectric and capacitive micromachined ultrasonic transducers, enabling integration with skin-conformal polymer-based CMUT arrays. As a host-agnostic acquisition front-end, it exposes standard data and power interfaces for BLE- and Wi-Fi-based wearable hosts. We demonstrate wireless transmission with external BLE and Wi-Fi modules and project 1-2 days of BLE operation at $50 \mathrm{Hz}$ PRF and over 3 h of Wi-Fi streaming at $300 \mathrm{Hz}$ PRF using a $300 \mathrm{mAh}$, $6.4 \mathrm{g}$ Li-Po cell. WULPUS PRO establishes a new class of fully programmable, B-mode-enabled, ultra-low-power wearable ultrasound platforms.