A Miniaturized Low-Intensity Ultrasound Device for Wearable Medical Therapeutic Applications

Low-intensity ultrasound has drawn increasing attention recently as a non-invasive modality for medical therapeutic applications. Current commercially available low-intensity ultrasound devices are bulky and expensive. In this paper, a battery-powered miniaturized device is proposed to generate low-intensity therapeutic ultrasound. The proposed device consists of a custom Application-Specific Integrated Circuit (ASIC), an off-chip digital control block, and a piezoelectric transducer. The ASIC, which integrates a DC-DC boost converter and a transducer driver, is implemented in TSMC's 0.18 mu m BCD Gen2 process. Measurement results show that a maximum output voltage of 14 V is achieved by the proposed fully-integrated DC-DC boost converter with a battery supply voltage of 3.7V. The peak power conversion efficiency is 29% and the output power at the peak power conversion efficiency is 105 mW. The on-chip transducer driver employs a half-bridge circuit with two n-type devices at the output stage. A high-voltage level shifter with low power consumption and short propagation delay is proposed in this paper for the high-performance operation of the half-bridge transducer driver. The piezoelectric transducer is a customized transducer with a resonance frequency of 1.5 MHz. At this frequency, the proposed low-intensity ultrasound device is able to generate continuous-wave ultrasound with a therapeutic power intensity of 32 mW/cm(2). The proposed low-intensity ultrasound device is low-cost, compact, and light-weight, which enables affordable, and wearable applications.