[2025] High Density Stretchable Signal Lines for Ultrasound-Based Brain Implants

Focused ultrasound neuromodulation is an emerging therapeutic modality that can
stimulate targeted regions deep in the brain [1]. One of the challenges in using
ultrasound for neuromodulation is the skull, which attenuates ultrasound, especially
at higher frequencies. This limits the spatial resolution achievable with transcranial
focused ultrasound neuromodulation because the size of the focal spot is inversely
proportional to frequency. A promising approach to overcome the effects of the skull
and achieve higher a higher spatial resolution is to implant an ultrasound phased
array, capable of electronically steering an ultrasound beam, between the skull and
the brain.
A major challenge for implanted ultrasound devices is on how to achieve high density
interconnects to individually address and support all the piezoelectric elements of
the device. Indeed, ultrasound phased arrays require a dense grid of a high number
of piezoelectric elements with a pitch dictated by the ultrasound wavelength.
Furthermore, this means that to increase resolution by increasing the frequency, the
density of interconnects also needs to increase, making them a critical component.
This project aims to design interconnects that achieve the required density while 1)
being stretchable, to enable the array to conform to the complex shape of the
intracranial space, 2) having sufficiently good electrical characteristics in terms of
impedance and cross talk, and 3) being sufficiently resilient and reliable for the
implant procedure. For this, multiple avenues could be explored. For example:
structured metal microfabrication on stretchable polymeric substrates, intrinsically
stretchable conductors, and stretchable/conductive composites.

Assignment

1st part: Literature review of stretchable interconnect technologies and of their
adequacy for ultrasound phased arrays
2nd part: Design, simulation, fabrication and experimental validation of a stretchable
interconnect system for high density ultrasound arrays

Requirements

MSc students from Microelectronics, Biomedical Engineering, Applied Physics, or
other relevant backgrounds. Interested students should include their CV, the list of
courses attended, and a motivation letter.

Contact

Last modified: 2025-02-28