An Implantable Multi-channel Neural Electrical Stimulation System

An implantable multi-channel neural electrical stimulation system is designed,which is applicable to the motor control of rats by stimulating some particular brain areas of the rats.It basically consists of two parts,the remote command transmitter device(RCTD) and the implantable multi-channel neural stimulation system(IMNSS).The RCTD includes a control software(designed by VC++ in PC or laptop) and a wireless transmitter(realized by CC2430).The IMNSS is mainly composed of a wireless receiver,a pulse-width-modulation to analog converter(PWMAC) circuit,a voltage-controlled constant current source,and a multi-channel analog switch.For the IMNSS,by using CC2430 as micro controller unit(MCU), a microcontroller and a wireless communication module are integrated into one chip,which can reduce the size and weight. Thus,the IMNSS is 20 mm×25 mm×3 mm in size,7 g in weight(including 3 g,the weight of a rechargeable lithium ion battery),and with a 3 hours working time.The PWMAC can make CC2430 without DAC(digital-to-analog converter) function generate adjustable voltage signals.Through the voltage-controlled constant current source,the adjustable voltage signals will generate adjustable constant current signals,which will generate adjustable biphasic constant current source signals for neural stimulation by the usage of the multi-channel analog switch.Lateral medial forebrain bundle(MFB) and bilateral primary somatosensory cortex and barrel field(S1BF) are selected as the brain sites to be stimulated,and each brain site is implanted into a pair of electrodes.Each pair of electrodes as one channel is connected with the IMNSS,so that the RCTD can regulate the parameters of the neural stimulation signal of each channel in real time.Experiments show that current stimulation of MFB with proper parameters can generate virtual reward which drives a rat to move forward,and current stimulation of S1BF with proper parameters can be used to make a rat turn left or right.