A Wireless Network of Microimplants For Neural Recording and Microstimulation Jihun Lee 1 , Ah-Hyoung Lee 1 , Vincent Leung 2 , Jiannan Huang 3 , Peter Asbeck 3 , Patrick P . Mercier 3 , Stephen Shellhammer 4 , Lawrence Larson 1 , Farah Laiwalla 1 , and Arto Nurmikko 1 1 Brown University, 2 Baylor University, 3 University of California San Diego, 4 Qualcomm Introduction In-vivo Networking Experiments Block diagram for Neurograin Network Future Work and Reference ▪ We present a wireless multichannel system composed of wirelessly networked submillimeter size electronic microchips (“Neurograins”) [1]. ▪ An electromagnetic link at ~1 GHz enables bidirectional communication and control of individual neurograin performing either a neural recording or stimulating. ▪ The wireless network operates on a customized time division multiple access (TDMA) protocol designed to scale up to 1000 neurograins [2]. BPSK: Binary Phase Shift Keying, ASK-PWM: Amplitude-shift Keying and Pulse Width Modulation In-vivo Neurograin Recording ▪ Post-processing was done to make with gold epicortical electrodes on recording or attach intracortical tungsten electrodes for stimulation. [3] ▪ Multi-node recording Neurograin collected 40 Hz sinusoidal signals in saline simultaneously. ▪ Array of stimulation Neurograin generated pattern stimulation in saline in a response to downlink commands assigning one chip at a time to stimulate. References [1] Lee, Jihun, et al. "Wireless Ensembles of Sub-mm Microimplants Communicating as a Network near 1 GHz in a Neural Application." bioRxiv (2020). [2] Lee, Ah-Hyoung, et al. "A scalable and low stress post-CMOS processing technique for implantable microsensors." Micromachines 11.10 (2020): 925. [3] Leung, Vincent W., et al. "Distributed Microscale Brain Implants with Wireless Power Transfer and Mbps Bi- directional Networked Communications." 2019 IEEE Custom Integrated Circuits Conference (CICC). IEEE, 2019. * Research supported by a gift to Brown University ▪ Our goal is to develop intracortical Neurograin by porting 65 nm-based Neurograin into 22 nm node. ▪ The next-generation Neurograin will perform stimulation and recording under bidirectional communication. Characterization of System-on-chip Workshop on Advanced NeuroTechnologies Intracortical Neurograin Neurograins on U.S dime (each chip 650 μm × 650 μm × 250 μm) Wireless communication (10 Mbps Uplink, 1 Mbps Downlink) ▪ External wireless hub with software-defined radio transmits RF energy/downlink command and received backscattered data ▪ Each neurograins preforms 1) RF energy harvesting, 2) wireless data communication and 3) ECoG neural recording or biphasic current stimulation ▪ Neurograin system is demonstrated as a cortical implant in a small animal (rat) model with anatomical limitations restricting the implant to 48 neurograins. ▪ 3 coil system establishes efficient wireless link with Neurograin ensemble. ▪ Under Ketamine, an ensemble of 48 recording neurograins captured 1) spontaneous low frequency oscillation. 2) post-stimulus evoked field responses dependent on anesthesia. In-vivo Neurograin Stimulation ▪ With ensemble of stimulating neurograins, 1) 100 Hz stimulation evoked pulse-width dependent local field responses. 2) 400 Hz current injection triggered neural burst activities. *Any unauthorized use of these materials may violate copyrights and/or trademarks.