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

Chunkyun Seok, Feysel Yalcin Yamaner, Mesut Sahin, Omer Oralkan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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-μ m HV BCD process within a die size of 2.5 × 2.5 mm^2. 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 (I_SPPA) of 33.5 W/ cm^2, with a lateral full width at half maximum (FWHM) of 0.6 mm at a depth of 3.5 mm.

Original languageEnglish (US)
Pages (from-to)692-704
Number of pages13
JournalIEEE Transactions on Biomedical Circuits and Systems
Volume15
Issue number4
DOIs
StatePublished - Aug 2021

All Science Journal Classification (ASJC) codes

  • Biomedical Engineering
  • Electrical and Electronic Engineering

Keywords

  • ASIC
  • brain stimulation
  • capacitive micromachined ultrasonic transducer (CMUT)
  • freely behaving animals
  • neurostimulation
  • ultrasound

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