| The spinal cord injury is the most common cause of neurogenic bladder. Especially for the patients with spinal cord injury above sacral section, there is a very high proportion with voiding and storing double dysfunction. With the development of implanted biomedical microelectronic devices used for diagnosis or cure in many diseases, bladder function rebuilding based on functional electrical stimulation (FES) technology plays an increasingly important role. Our research group proposed an independent research of bladder function rebuilding system based on the principle of sacral nerve stimulation to bridge the gap of domestic market. Contents of this paper are part of the system, the goal is to achieve multi-channel signal transcutaneous wireless transmission, and the experimental results have verified the function credibility and stability, which bring possibility of implanting.According to the overall functional requirements of sacral nerve stimulation system, solutions and structures of multi-channel FES-system based on signal transcutaneous wireless transmission have been proposed firstly. And the working frequency, packaging scheme and integration solutions also have been discussed.Then, electromagnetic analysis of the coils network is made based on the principle of electromagnetic coupling. Transmitting coil and receiving coils are made of copper wire and PCB separately, and their electrical parameters are tested by network analyzer based on a two-port network model. While improving the transmission efficiency of the system, selecting the parallel resonant compensation make coupling structure optimized.Furthermore, the in-vitro transmitting module and in-vivo receiving module of multi-channel FES-system based on signal transcutaneous wireless transmission have been designed and simulated. For in vitro transmitter module, this paper presents three options. The structure based on LC oscillator is chosen after simulation and analysis, used to implement low-frequency signal modulation and power amplification. And passive demodulation of the in-vivo receiving module is analyzed and fabricated. Joint test confirmed that two parts of the circuit can work normally.After realization of each module, the systematic tests have been carried out, which include signal charateristies experiment, three mediums in vitro experiment, as well as 6 animal experiments. Experimental results demonstrate that the sacral root stimulation system attained a stable output within a reasonable range of position misalign, and achieved multi-channel signal parallel transmission with less interference between channels. |
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