Flexible parylene-thread bioprobe and the sewing method for in vivo neuronal recordings

•We fabricated a flexible parylene-thread bioprobe and proposed the implantation method based on conventional sewing method.•A device-holding protocol was proposed to enable a stress-free “catch” and “release” of the needle.•EMG signals were recorded from the mouse’s MG muscle.•Both the LFP and the spike were recorded from the mouse’s visual cortex in in vivo chronic recording. Multichannel recording of the electrical signals from soft biological tissue of brain is an important technique in electrophysiology. However, penetration of conventional rigid needle-electrodes causes physical-stress to the tissue and induces the tissue damage, making the stable recording impossible. The approach reported here involves the use of a flexible “thread-like” device with microelectrodes that enables precise penetration and placement inside the brain tissue, with the help of a guiding microneedle, similar to sewing mechanism. A device-holding protocol, which uses a dissolvable material, is proposed to enable a stress-free “catch” and “release” of the needle. The device is placed in the primary visual cortex (V1) of an in vivo mouse and both the local field potentials (LFP) and the action potentials (spike) are recorded. For over a period of two weeks after device implantation, no remarkable decrease in mouse’s weight is observed. Therefore, we conclude that the proposed sewing thread-device enhances the recording of neuronal signals while minimizing the device–induced stress.