Efficient Recording of Rodent Neuronal Activity Using Microelectrodes With a Battery Free Wireless Neurosensing System

To address the limitations of existing wired and wireless battery-powered designs for monitoring neuronal activity, our team has developed a novel implantable, battery-free, Wireless Neurosensing System (WiNS). Here, we aim to develop low-impedance microelectrodes to improve the minimum detectable signal for recording intracranial activity. For the first time, WiNS is evaluated in vivo to capture multiunit neuronal spiking, after adding a passive impedance matching (PIM) network. We explored different techniques for fabricating microelectrodes and demonstrated the resulting reduction in our system signal attenuation. Specifically, we were able to recover signals of 20 µVpp, a 10-fold improvement over previous designs. Furthermore, we fabricated microdrives to facilitate neuronal recording activity with WiNS and a wired system as a “gold” standard comparison. With the necessary components for our experiment, rat somatosensory cortex evoked neural activity was recorded. Broadband electrophysiological recordings were analyzed on multiple scales by evaluating the low-frequency component for elements corresponding to local field potentials (LFP) and the high-frequency component for multiunit neuronal spiking activity. LFP analysis involved the extraction of somatosensory evoked potentials to evaluate the recordings of each system. Concurrently, the neuronal spiking contributions were analyzed for spike occurrence and characteristics. Results at both scales indicate that recordings performed with WiNS are comparable with those of a wired system (p-value <0.050, Mann-Whitney Test). Therefore, the addition of PIM and the careful design of microelectrodes, led to the validation of WiNS using commercially available wired system. Furthermore, WiNS enables countless applications in neuroscience for continuous monitoring of neuronal activity.