MSc thesis project proposal

[2020] CMOS Integrated circuits for minimally invasive brain stimulation through ultrasonic neurovascular stents

Implantable electrodes in the brain have been used in the past decades as an alternative therapeutic modality to pharmaceuticals, such as deep brain stimulation for Parkinson’s disease. However, due to the risks of brain surgery, patients are only eligible for implantation after the pharmaceutical drugs stopped having the desired effect, and even so, only approximately 10% of patients are approved for surgery, which means that 90% of patients no longer have the benefits of pharmaceutical drugs and are not eligible for deep brain stimulation. Similar statistics occur for other diseases of the nervous system, such as epilepsy. For this reason, there is a high demand for non-invasive and minimally invasive therapies.

Ultrasound neuromodulation is emerging as a promising non-invasive alternative to implantable electrodes in the treatment of brain diseases, since it can propagate several centimeters into the tissue, it can be focused with better spatial resolution than other non-invasive modalities (TMS, TdCS), and can be used to either stimulate or inhibit neuronal activity. However, the skull poses a fundamental limitation in the use of ultrasound for brain diseases, since it is a very high acoustic absorber. For this reason, for ultrasound to be able to go through the skull and reach the desired region of the brain with high enough intensity to modulate neuronal activity, researchers typically have to sacrifice the spatial resolution of the focused ultrasound to a value which is up to two orders of magnitude worse than implantable electrodes.

This project explores the use of the brain neurovasculature as a minimally invasive path to bypass the skull for high precision ultrasound stimulation and inhibition of neuronal activity by means of an active ultrasonic neurovascular stent. A passive ultrasonic neurovascular stent is already being developed, and the goal of this project is to develop a CMOS circuit to interface with ultrasound transducers capable of generating focused ultrasound waves with the necessary frequency, pulse repetition frequency, pulse duration and intensity to stimulate or inhibit neuronal activity.

Assignment

1st part: Literature review of ultrasound transducer circuit interfaces for neuromodulation

2nd part: Design of a CMOS circuit interface for ultrasound transducers

Requirements

At the end of the project students should have a validated design including post-layout simulations, and a final report, which could lead to a conference paper submission. Depending on available time, circuits might also be taped-out, allowing for bench testing and validation.

Contact

dr. Tiago Costa

Bioelectronics Group

Department of Microelectronics

Last modified: 2021-02-10