MSc thesis project proposal

[2016; already taken] Epidural spinal cord electrical stimulation (ESCS)

Background

Epidural spinal cord electrical stimulation (ESCS) has been used as a means to facilitate locomotor recovery in spinal cord injured humans. Electrode arrays, instead of conventional pairs of electrodes, are necessary to investigate the effect of ESCS at different sites. These usually require a large number of implanted wires, which could lead to infections.

To facilitate animal experiments, an electrode array with embedded ASICs [1] suitable for implantation inside the rat’s spinal canal was previously developed and tested [2]. The array can deliver current pulses (up to 1 mA, 100 pulses per second) and supports interleaved stimulation with independent control of the stimulus parameters for each pulse. It features low power consumption, and ensures maximum testing versatility by providing independent access to twelve electrodes in any configuration and very versatile stimulation timing and pulse duration. It communicates via only three tracks with its control unit.

The control unit is used to store the user defined parameters, and generate the stimulus current as well as control the timing of the stimulation. The unit is currently external, comprises a microcontroller, a current source, a dc-dc converter and several other components on a PCB, and is powered through a USB connected to a PC.
Br>A graphical user interface (GUI) (currently designed in Visual Studio, C#) serves as the tool through which the user can modify the stimulation protocols. The GUI gives the user the freedom to select up to 5 different stimulation patterns and independently define their individual parameters (pulse amplitude, pulse width, interphase delay) and electrode configurations. In addition, the user can define the stimulus repetition rate.

The external control unit and active electrode array system is capable of a swift change of parameters (in microseconds) and could be dynamically adjusted in real-time several times during a gait cycle, providing great versatility for testing.

Moving towards a fully implantable system

We would like to implement the external control unit into an implantable (subcutaneous) component.

Assignment

In this project we are looking for a student to work on the system integration. The student will have the opportunity to design, fabricate and test a prototype of the subcutaneous unit. The work would involve improving the system level design and performance of the existing device by exploring alternative topologies, and exploring methods for powering the implant (this can be a battery or any other powering method suitable for implants) while taking into account heat and size considerations to avoid tissue damage. In addition, the student would explore packaging possibilities and could come up with novel system integration techniques.

References:
[1] V. Giagka, C. Eder, N. Donaldson, and A. Demosthenous, “An implantable versatile electrode-driving ASIC for chronic epidural stimulation in rats,” IEEE Trans. Biomed. Circuits Syst., vol. 9, no. 3, pp. 387 – 400, Jun. 2015.
[2] V. Giagka, A. Demosthenous, and N. Donaldson, “Flexible active electrode arrays with ASICs that fit inside the rat’s spinal canal,” Biomed. Microdev., vol. 17, no. 6, pp. 106 – 118, Dec. 2015.

Requirements

MSc student in Biomedical Engineering or Electrical Engineering, having passed/taken the courses Bioelectricity and Active Implantable Biomedical Microsystems.

Contact

dr. Vasiliki Giagka

Bioelectronics Group

Department of Microelectronics

Last modified: 2016-09-21