Characterization and optimization of the process flow of flexible neural probes

More than two weeks ago

Help develop the future brain-machine interfaces

Electrical neural recordings are based on the measurement of voltage differences by an electrode located in the proximity of neurons. Currently at Neuro-Electronics Research Flanders (NERF), in collaboration with imec, we are working on developing large-scale, high-density, flexible neural probes that can offer high spatial resolution and spatial sampling coverage of the brain tissue. To overcome some limitations of passive neural probes, such as limited electrode count and connector size, we have decided to employ active electronic circuits that allow the multiplexation and amplification of the neural signals.

The flexible neural probes we are developing are based on thin-film transistors (TFTs) that utilize metal oxide semiconductors as the channel layer. These devices have attractive characteristics, such as high uniformity, high electron mobility (10 cm2/V‧s), and their fabrication at low temperatures on plastic substrates. The fabrication flow of our TFTs was initially developed at imec to be used for flat-panel displays. Since the operational conditions in-vivo application are harsher, changes in the process flow, material stacks and interface should be implemented to customize to the requirements for neural probes.

The objective of this thesis is to work on the characterization of the flexible neural probes. The tasks will include their electrical and mechanical characterization. Additionally, the project will include some work on the readout software of the high-density probes. The readout system will be based on commercial silicon chips for bio-potential monitoring and a field-programmable gate array (FPGA) will be used to address the electrode array. The student will be responsible for the hardware and software interface between the probes and the computer, exploring different implementations that maximize the number of electrodes that can be read simultaneously. Employing the developed system, the neural probes fabricated at imec will be characterized both in vitro and in vivo.

Conditioned to the status of the project the moment the student incorporates the group, the thesis might include the microfabrication of the neural probes, and exploration of variations of the current process flow in order to achieve devices with excellent characteristics for the measurement of biosignals. Significant effort will be placed on improving stability of the device in saline environments to avoid delamination of the different layers, which limits the life time of our devices. Previous cleanroom and fabrication experience would be desired for this part of the project.​

Type of project: Internship

Duration: 6 months

Required degree: Master of Science, Master of Bioengineering, Master of Engineering Science, Master of Engineering Technology

Required background: Nanoscience & Nanotechnology, Physics, Mechanical Engineering, Materials Engineering, Electrotechnics/Electrical Engineering, Electromechanical engineering, Biomedical engineering, Bioscience Engineering

Supervising scientist(s): For further information or for application, please contact: Sebastian Haesler (

Imec allowance will be provided for students studying at a non-Belgian university.

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