IntegraBrain: A multi-modal neural interface for the detection and suppression of focal epilepsy

Focal cooling has been demonstrated as a promising treatment strategy for patients with medically intractable epilepsy. Cooling actuation is achieved via an invasive interface positioned in direct contact with neural tissue of the epileptic foci. Seizure suppression by focal cooling has been demonstrated extensively. However, pre-clinical proof-of-concept systems that have been produce thus far are too bulky and mechanically stiff. Long-term implantation of these devices would risk inducing significant compression injury and localised glial scaring over time.
In this thesis presents the efforts to assemble a miniaturised, multi-modal interface that is capable of simultaneously performing electrocorticography (ECoG) recording, temperature monitoring and focal cooling. Comprising of a solid-state thermoelectric element, a microfluidic heat management system, integrated thermocouples, ECoG electrodes and supporting electronic circuitry, a systemic implementation approach was used to produce a tightly integrated system.
The Interface consists of discreate electronic components embedded in a mechanically soft matrix with the dimensions 9.5 x 9.5 x 2.5mm. This is realised through the leveraging of direct ink writing (3D printing) biocompatible silicones and electrically conductive Graphite-PDMS composites. Integration of composite electrodes allows for ECoG sensing whilst maintain device softness.
In Vitro interface systems verification was conducted using hydrogel-based neural tissue thermal models. At the interface-model tissue boundary, rapid cooling rates of ~3°Cs-1 were achieved during 14°C ΔT cooling runs. System power consumption is recorded to peak at 7.84W on cooling start and 2.6W during steady state of a 15°C ΔT cooling run. System maturation presented the opportunity to conduct acute In Vivo animal studies using the 4-AP seizure model. Initial data collected demonstrate reliable cortical tissue cooling down to 18°C. Comparison of nominal seizure recordings to those during active cooling indicate successful seizure suppression with seizure activity suppression increasing as cooling temperature decreases. A ~67% reduction in broadband seizure magnitude (0-30Hz) was recorded when cooling to 18°C.
Work presented here represents an evolution in focal cooling interface design beyond the existing solutions and a step towards a clinically viable device for patients.