TinyProbe: A Wearable 32-Channel Multimodal Wireless Ultrasound Probe

The need for continuous monitoring of cardiorespiratory activity, blood pressure, bladder, muscle motion analysis, and more is pushing for research and development of wearable ultrasound (US) devices. In this context, there is a critical need for highly configurable, energy-efficient wearable US systems with wireless access to raw data and long battery life. Previous exploratory works have primarily relied on bulky commercial research systems or custom-built prototypes with limited and narrowly focused field applicability. This article presents TinyProbe, a novel multimodal wearable US platform. TinyProbe integrates a 32-channel US receive (RX)/transmit (TX) front-end, including TX beamforming ( ${64}\;{V}_{\textit {pp}}$ excitations, 16 delay profiles) and analog-to-digital conversion (up to 30 Ms/s, 10 bit), with a Wi-Fi link (21.6 Mb/s, UDP), for wireless raw data access, all in a compact ( ${57} \times {35} \times 20$ mm) and lightweight (35 g) design. Using advanced power-saving techniques and optimized electronics design, TinyProbe achieves a power consumption of <1 W for imaging modes (32 ch., 33 Hz) and <1.3 W for high-PRF Doppler mode (2 ch., 1400 Hz). This results in a state-of-the-art power efficiency of 44.9 mW/Mb/s for wireless US systems, ensuring multihour operation with a compact 500 mAh Li-Po battery. We validate TinyProbe as a versatile, general-purpose wearable platform in multiple in vivo imaging scenarios, including muscle and bladder imaging, and blood flow velocity measurements.

I. Introduction

Ultrasound (US) imaging is the second most used biomedical imaging modality [1] (after X-rays), and it enables safe and noninvasive inspection of the human body. US offers many desirable features, including real-time operation, high spatiotemporal resolution, low cost, and portability. US is also very flexible: depending on the targeted application, US can also be operated in different modalities, including A-mode, B-mode, C-mode, and Doppler [2]. These capabilities make US highly valuable not only for clinical and point-of-care diagnostics [3] but also for long-term, continuous monitoring during everyday’s life [4].