Design of a Quasi-Adiabatic Current-Mode Neurostimulator Integrated Circuit for Deep Brain Stimulation

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dc.contributor.advisorNewcomb, Robert Wen_US
dc.contributor.authorMandal, Arindamen_US
dc.contributor.departmentElectrical Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2018-09-19T05:30:20Z
dc.date.available2018-09-19T05:30:20Z
dc.date.issued2018en_US
dc.description.abstractElectrical stimulation of neural tissues is a valuable tool in the retinal prosthesis, cardiac pacemakers, and Deep Brain Stimulation (DBS). DBS is being to treat a growing number of neurological disorders, such as movement disorder, epilepsy, and Parkinson’s disease. The role of the electronic stimulator is paramount in such application, and significant design challenges are to be met to enhance safety and reliability. A current-source based stimulator can accurately deliver a charge-balanced stimulus maintaining patient safety. In this thesis, a general-purpose current-mode neurostimulator (CMS) based upon a new quasi-adiabatic driving technique is proposed which can theoretically achieve more than 80% efficiency with the help of a dynamic high voltage supply (DHVS) as opposed to most conventional general-purpose CMS having less than 25% efficiency. The high-voltage supply is required to withstand the voltage seen across the electrodes (>10V) due to the time-varying impedance presented by the electrode-tissue interface. The overall efficiency of the designed CMS is limited by the efficiency of the DHVS. A HVDD of 15V is created by the DHVS from an input voltage (VDD) of 3V. The DHVS circuit is made by cascading five charge pump circuits using the AMI 0.5µm CMOS process. It can maintain more than 60% efficiency for a wide range of load current from 25µA to 1.4mA, with peak efficiency at 67% and this is comparable with existing specific-purpose state-of-the-art high-voltage supplies used in a current stimulator. The stimulator designed in this thesis employs a new efficient charge recycling mechanism to enhance the overall efficiency, compared to the existing state-of-the-art CMSs. Thus, the overall CMS efficiency is improved by 20% to 25%. A current source, programmable by 8-bit digital input, is also designed which has an output impedance greater than 2MΩ with a dropout voltage of only 120mV. Measurements show voltage compliance exceeding +/-15V when driving a biphasic current stimulus of 10µA to 2.5mA through a simplified R-C model of the electrode-tissue interface. The voltage compliance is defined as the maximum voltage a stimulator can apply across the electrodes to achieve neural stimulation.en_US
dc.identifierhttps://doi.org/10.13016/M2222R92T
dc.identifier.urihttp://hdl.handle.net/1903/21409
dc.language.isoenen_US
dc.subject.pqcontrolledElectrical engineeringen_US
dc.subject.pquncontrolledCurrent-Mode-Stimulatoren_US
dc.subject.pquncontrolledDeep brain stimulaionen_US
dc.subject.pquncontrolledDynamic high-voltage scalingen_US
dc.subject.pquncontrolledenergy efficiencyen_US
dc.subject.pquncontrolledHigh-voltage complianceen_US
dc.subject.pquncontrolledQuasi-adiabaticen_US
dc.titleDesign of a Quasi-Adiabatic Current-Mode Neurostimulator Integrated Circuit for Deep Brain Stimulationen_US
dc.typeThesisen_US

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