Brain stimulation is an effective approach to treat neurological disorders. Among
various brain stimulation modalities, ultrasound brain stimulation stands out due to the non-
invasiveness and precise spatial-resolution of ultrasound acoustic waves[1], [2]. Traditionally,
clinical ultrasound transducers for transcranial Focused Ultrasound (tFUS) typically consists
of single-element transducers, which tend to be bulky, rely on large power-intensive
electronics, and limited to focus at a single target area. To address multiple brain regions, these
probes require manual repositioning. Recent advancements have led to the integration of
piezoelectric ultrasound transducers into CMOS technology, enabling significant
miniaturization and enhanced reconfigurability through three-dimensional beamforming[3].
However, this integration typically comes at the expense of decreased power-efficiency due to
ultrasound absorption by the silicon substrate. Alternatively, [4] introduced capacitive
micromachined ultrasound transducers (CMUTs), flip-chip bonded onto CMOS circuits to
generate focused ultrasound pressure waves. Although the transducers were able to produce
higher acoustic focal pressure as they were driven by higher voltages, it was at the expense of
increased power consumption, which can lead to excessive heat at the chip-tissue interfaces.
Thus, I will present engineering strategies aimed at improving the power efficiency of
piezoelectric ultrasound transducers integrated onto CMOS electronics, with the goal of
making these devices viable for wearable or implantable applications.
References:
[1] A. Fomenko, C. Neudorfer, R. F. Dallapiazza, S. K. Kalia, and A. M. Lozano, ‘Low-intensity
ultrasound neuromodulation: An overview of mechanisms and emerging human
applications’, Nov. 01, 2018, Elsevier Inc. doi: 10.1016/j.brs.2018.08.013.
[2] J. Blackmore, S. Shrivastava, J. Sallet, C. R. Butler, and R. O. Cleveland, ‘Ultrasound
Neuromodulation: A Review of Results, Mechanisms and Safety’, Jul. 01, 2019, Elsevier
USA. doi: 10.1016/j.ultrasmedbio.2018.12.015.
[3] T. Costa, C. Shi, K. Tien, J. Elloian, F. A. Cardoso, and K. L. Shepard, ‘An Integrated 2D
Ultrasound Phased Array Transmitter in CMOS with Pixel Pitch-Matched Beamforming’,
IEEE Trans Biomed Circuits Syst, vol. 15, no. 4, pp. 731–742, Aug. 2021, doi:
10.1109/TBCAS.2021.3096722.
[4] C. Seok, O. J. Adelegan, A. O. Biliroglu, F. Y. Yamaner, and O. Oralkan, ‘A Wearable
Ultrasonic Neurostimulator - Part II: A 2D CMUT Phased Array System with a Flip-Chip
Bonded ASIC’, IEEE Trans Biomed Circuits Syst, vol. 15, no. 4, pp. 705–718, Aug. 2021,
doi: 10.1109/TBCAS.2021.3105064.