An integrated circuit towards improved management of epilepsy and other neurological conditions
Document TypePhD thesis
Access StatusThis item is embargoed and will be available on 2023-01-19.
© 2020 Kyle Slater
Epilepsy is the second-most common neurological disorder, with an estimated prevalence of 1% worldwide. Antiepileptic drugs (AEDs) are the frontline treatment but, despite more than 25 agents available, there can be significant difficulties in finding a treatment plan that controls seizures without unacceptable side effects. Furthermore, approximately 30% of patients do not obtain full control of seizures with the available AEDs. Therefore, there exists a need for novel therapies. Therapeutic electrical stimulation of the brain and peripheral nervous system has shown great promise in treating those with refractory epilepsy, but still little is known about the mechanisms underlying this. Recent work looking at prolonged recordings of the brain has revealed a deep rhythmicity to seizures that may provide a method of developing patient-specific prediction algorithms that could be used to titrate electrical stimulation therapies. What is missing in research and in clinical practise is an implantable device which provides enough flexibility to explore new paradigms and adapt to suit the needs of the patient. Safety considerations of implantable devices necessarily precedes large-scale clinical evaluation, and this has prevented exploration of speculative higher density arrays, which come at a cost to power, complexity and mechanical reliability with no guarantee of improvement to efficacy. Rather than redesign the system from scratch, this PhD thesis asks, “how can existing implantable technology be leveraged to create flexible high-density brain recording and stimulation systems?” In response to this question, an integrated circuit called XPAND was designed to enable seamless expansions of electrode count for a wide variety of commercial stimulators. Comprising a 6 x 64 element high voltage crosspoint switch powered and configured entirely using biphasic stimulation pulses, XPAND was designed with clinical safety in mind. Fabricated in Austria Microsystems H35 high voltage CMOS process, key modules within the chip were characterised, and the crosspoint switch shown to simultaneously route high voltage stimulation and ECG signals.
Keywordsneural interfaces; brain machine interfaces; BMI; integrated circuits; implantable device; epilepsy treatment; epilepsy management; brain recording
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