11 March

Graphene Field-Effect Transistors as Flexible Neural Interfaces for Intracortical Electrophysiology

Thursday 11 March 2021, 10:30pm

ICN2 Seminar Hall, ICN2 Building, UAB


PhDAndrea Bonaccini Calia 

Directors: ICREA Prof. Jose Antonio Garrido, Advanced Electronic Materials and Devices Group Leader at ICN2.

Short Abstract: Recent years have witnessed novel technology developments of neural implants for medical applications, which are expected to help unveil unknown functionalities of the central nervous system. Currently available neural implants offer a modest clinical efficacy, partly due to the limitations posed by the invasiveness of the implants materials, the related technology and by the metals used at the electrical interface with the tissue.

Development of flexible electronics using biocompatible materials is key for the realisation of minimally invasive neural implants, which can be chronically implanted without causing rejection from the immune system. A very promising development is the use of two dimensional materials, such as graphene, for bioelectronics applications. Graphene solution-gated field effect transistor (gSGFET) is one of the emerging new neural technologies.

In this PhD thesis, arrays of gSGFETs have been fabricated and optimized in terms of sensitivity and signal-to-noise ratio, adopting wafer-scale micro-fabrication methods. The 1/f noise of gSGFETs has been characterised, studying the effect of contact noise and channel noise.

Flexible and ultra-thin neural probes containing arrays of gSGFETs have been successfully fabricated and used during in vivo micro-electro-corticography recordings. Neural activity recordings have been obtained with flexible graphene depth neural probes in relevant awake animal models of seizures and established epilepsy. In addition to the recording of characteristic epilepsy-related biomarkers in conventional frequency bands, it was possible to simultaneously detect and map infra-slow activity through different cortical layers and subcortical regions. The infra-slow activity (< 0.1Hz) is suspected to contribute to the pathophysiology of several neurological disorders such as stroke, traumatic brain injury, migraine and epilepsy, and is thus of high clinical relevance.

Furthermore, the assessment of the long term recording stability and functionality, as well as the biocompatibility of the gDNP have also been demonstrated as part of this thesis work.