2021 journal article

A Wearable Ultrasonic Neurostimulator-Part I: A 1D CMUT Phased Array System for Chronic Implantation in Small Animals

IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, 15(4), 692–704.

author keywords: ASIC; brain stimulation; capacitive micromachined ultrasonic transducer (CMUT); freely behaving animals; neurostimulation; ultrasound
MeSH headings : Animals; Equipment Design; Transducers; Ultrasonics; Ultrasonography; Wearable Electronic Devices
TL;DR: A wireless ultrasonic neurostimulator, aiming at a truly wearable device for brain stimulation in small behaving animals, and hydrophone-based acoustic measurements were performed to demonstrate the beam forming and steering capability of the proposed system. (via Semantic Scholar)
UN Sustainable Development Goal Categories
7. Affordable and Clean Energy (OpenAlex)
Source: Web Of Science
Added: September 27, 2021

In this work, we present a wireless ultrasonic neurostimulator, aiming at a truly wearable device for brain stimulation in small behaving animals. A 1D 5-MHz capacitive micromachined ultrasonic transducer (CMUT) array is adopted to implement a head-mounted stimulation device. A companion ASIC with integrated 16-channel high-voltage (60-V) pulsers was designed to drive the 16-element CMUT array. The ASIC can generate excitation signals with element-wise programmable phases and amplitudes: 1) programmable sixteen phase delays enable electrical beam focusing and steering, and 2) four scalable amplitude levels, implemented with a symmetric pulse-width-modulation technique, are sufficient to suppress unwanted sidelobes (apodization). The ASIC was fabricated in the TSMC 0.18-<inline-formula><tex-math notation="LaTeX">${\mu \rm {m}}$</tex-math></inline-formula> HV BCD process within a die size of 2.5 × 2.5 <inline-formula><tex-math notation="LaTeX">${\rm {mm}^2}$</tex-math></inline-formula>. To realize a completely wearable system, the system is partitioned into two parts for weight distribution: 1) a head unit (17 mg) with the CMUT array, 2) a backpack unit (19.7 g) that includes electronics such as the ASIC, a power management unit, a wireless module, and a battery. Hydrophone-based acoustic measurements were performed to demonstrate the focusing and beam steering capability of the proposed system. Also, we achieved a peak-to-peak pressure of 2.1 MPa, which corresponds to a spatial peak pulse average intensity (<inline-formula><tex-math notation="LaTeX">$\mathrm{I_{SPPA}}$</tex-math></inline-formula>) of 33.5 <inline-formula><tex-math notation="LaTeX">${\rm {W}/\rm {cm}^2}$</tex-math></inline-formula>, with a lateral full width at half maximum (FWHM) of 0.6 mm at a depth of 3.5 mm.