Design of Multi-Channel Monopolar Biphasic Voltage Stimulator for Implantable Biomedical Application

• Main Authors: Hsieh, Chia-Chi, 謝佳琪
• Other Authors: Ker, Ming-Dou
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/33xrmh

碩士 === 國立交通大學 === 電子研究所 === 106 === Neurological disorder causes unusual electrical activity in the brain that further affects the motor system, such as Parkinson’s disease and epilepsy, and there are seventy million population around the world suffer from these symptoms. Instead of drugs, electrical stimulation therapy has been proven to effectively restore some physical functions of patients by stimulating the abnormal nerve sites. With the development of CMOS process and bioelectronics, an implantable system-on-chip (SoC) device is able to be realized. Combing with microelectronics, medicine and biochemistry, the biomedical chip is made for different therapeutic applications. For example, closed-loop deep brain stimulation (DBS) system, implantable SoC for seizure control, and cochlear implant. According to the research of our biomedical group, a multi-channel voltage stimulator is proposed for Parkinson’s disease treatment. It completes every stimulation by delivering biphasic stimulus voltage to implantable pulse generator (IPG) case from one of the stimulator outputs. Considering of loading adaptation due to electrode-tissue impedance variation, a wide-range of stimulus voltage from ±0.5V to ±8V is designed. The adjustable output voltage is controlled by 4-bit binary code, which allows the system to generate 16 different amplitudes. Therefore, the proposed stimulator can be used in many biomedical applications through providing a proper stimulus voltage. In the treatment of Parkinson’s disease, voltage stimulation under 3.5V is often used. However, a voltage that is larger than 5V might be needed in the animal experiment of cochlear. For implantable SoC integration, safety, power consumption, and reliability have to be taken into consideration. A multi-charge-pump (MCP) system, which serves as power supply to stimulator and provides ±10V to support the circuit operation. The whole stimulator circuit has been fabricated in TSMC 0.25-μm HV USG 2.5-V/5-V/12-V CMOS process without device overstress, p-n junction breakdown issue, or p-n junction forward-leakage problem under 20V compliance voltage and negative voltage operation.