Development Of Programmable Multichannel Stimulator Used For Surface Array Electrodes

Functional electrical stimulation (FES) is a technique that uses electrical currents toactivate nerves innervating extremities affected by paralysis resulting from spinal cordinjury, head injury, stroke and other neurological disorders. FES can replace some ofdamaged nerves or simulated normal muscles voluntary movement to rebuild themovement function and repair damaged function. Surface electrical stimulate is a kind ofelectrical stimulation, which can be easily applied and avoid the possibility of surgery. Atpresent, most of the surface electrical stimulators prefer to use single or dual outputchannels design. Some of stimulator had achieved a goal of four-channel or eight-channeloutput. Surface array electrodes have been developed rapidly these years. It has a superiorperformance in improving stimulus selectivity and control capability. Multichannelstimulator is the basic equipment of functional electrical stimulation and surface arrayelectrodes research, which can provide a reference for the subsequent experimentalparameters design. Therefore, multichannel stimulator has important direct sense offunctional rehabilitation therapy, and can greatly promote the merge of engineering,medical research and the clinical rehabilitation. This thesis aims to develop amulti-channels functional electrical stimulator, which have a maximal24output channels.In this thesis, we design a multi-channels programmable stimulation system, and itstheory root in the electro-physiologic and the design of the last generation stimulationsystem of HUST. This system uses multi-IO ports C8051F020chipset as themicro-control unit. And the24channels can be controlled independently via usingindividually adjustable pulse parameters and waveform. The system adopts a LCD screenand membrane keyboard as the man-machine interface to achieve the friendly interface,convenient operation purpose. The hardware of the system is divided into several parts:the MCU controller, isolated power supply module, DAC, amplitude calculation andamplification circuit and the man-machine interface. MCU controller worked as the corepart, which send the quantified stimulation signal to the DAC, and acquired an output ofpolarity low voltage stimulation waveform. After the processing of amplitude calculationand amplification circuit, the original waveform has been transferred into bipolarwaveform. While the high-performance isolated power supply module upgrades the safetyof this stimulator, to make it accorded with some medical device standards. This systemuses Silicon Labs’ software to program and control the other parts of the circuit to generatethe target waveform. The whole design enhances portability and reduces weight.At last, the stimulator has been taken some basic performance test. The output ranges from0V to+15V, the stimulation frequency is28.1Hz and pulse width is300300μs. Atthe same time, the load capacity test meets the requirement of design. In the later research,this stimulator can be combined with the optimization of array electrodes for the use ofanimal and human experiments.