An artefact-resist optrode with internal shielding structure for low-noise neural modulation

Objective. The combination of optical manipulation of neural activities with electrophysiology recording is a promising technology for discovering mechanisms of brain disorders and mapping brain networks. However, fiber-based optrode is limited by the large size of light source and the winding of optical fiber, which hinders animal's natural movement. Meanwhile, the laser diode (LD)-based optrode restricted to the stimulation-locked artefacts will contaminate neural signal acquired from recording channels. Approach. Here, a reformative low-noise optrode with internal grounded shielding layer is proposed to mitigate the stimulus-locked artefacts generated during LDactivation for the application of optogenetics. Main results. The artefact mitigation capacity of grounded shielding was verified via simulation and experiments with transient amplitude of artefacts declined from over 5 mV to approximately 200 µV in-vitro. Meanwhile, the stimulation parameters were used based on previous studies by which neurons were activated without over heating the tissue as characterized by in-vitro studies (the output optical intensity is 823 38 mW mm-2). Furthermore, the microelectrodes were modified with Poly (3, 4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS) to increase the signal recording quality of the optrode. Finally, in-vivo optogenetics experiments were carried in the hippocampus of one mouse and the results showed our low-noise optrode was qualified to achieve high-quality neural recording (signal-to-noise ratio about 13) and specific neuron stimulation simultaneously. Significance. These results suggest the low-noise optrodes exhibit the ability of manipulating and recording neural dynamics and they are excellent candidates for neuroscience research.