Development Of Implantable Wireless Powered Neural Signal Acquisition And Stimulation System

With the development of biomedical and electronic technology,implantable medical devices have been widely used in biomedical applications.Among them,implantable neural interfaces play a crucial role in the treatment of neurological disorders.Neural interfaces can improve the lives of people with hearing impairments,limb dysfunction,or other neurological disorders,and can also assist neuroscientists in further decoding the information carried by neural signals.Neural signal acquisition and neural stimulation are key components of neural interfaces.Some of the existing implantable neural signal acquisition and stimulation systems are powered by batteries,which increase the size of the implanted device and reduce its safety.Some systems use wireless power transfer technologies to energize the implanted devices,which generally requires specially customized transmitters.If the customized transmitters are not easy to carry,it may affect the practical use of the device.In this paper,a miniaturized and portable fully implantable neural signal acquisition and stimulation system is proposed in response to the above issues.Firstly,the current research status of implantable neural signal acquisition and stimulation systems was introduced.Then,the characteristics and mechanisms of neural signals were discussed.According to the analysis of neural stimulation waveforms,a charge-balanced bidirectional constant-current stimulation waveform was selected.Moreover,the mechanisms of magnetically coupled resonant wireless power transfer was introduced.Then,the design of the implantable wireless neural signal acquisition and stimulation system was carried out.The front-end neural signal acquisition and stimulation circuit were designed using the RHS2116 chip.To reduce the system size,low-power Bluetooth chip was used as the main control chip to control the entire system,and low-power Bluetooth was also used for wireless communication.A wireless power receiving end was then designed.The overall size of the system is 15 mm*15 mm,with 33 mW～97 mW power consumption and only 1.3 g weight,which meets the requirements for implantation.The overall system functionality was validated by using a two-coil wireless power supply.Afterwards,in response to the drawbacks of the two-coil wireless power transfer transmitter,a three-coil magnetic-coupled resonant wireless power supply system was designed based on the mobile phone NFC reader as the transmitter.The system was modeled and theoretically analyzed,and the performance of the wireless power supply system was analyzed and tested.The implantable nerve signal acquisition and stimulation system was tested using the frog sciatic nerve-gastrocnemius muscle.Results showed that the mobile phone NFC reader can provide sufficient energy within an 8 mm distance.Finally,a wearable wireless power supply system structure was proposed to address the issue of requiring the mobile phone to be close to the implanted device when using the phone’s NFC as the power transmitter.The system was modeled and theoretically analyzed,and its performance was analyzed and tested.The feasibility of the wearable wireless power supply system design was tested with the frog sciatic nerve-gastrocnemius muscle.Results showed feasibility within a 7 mm range.