Factors affecting blind localization of a glass micropipette using a high-density microelectrode array

High-density microelectrode arrays (HDMEAs) provide the capability to measure extracellular electric potential from brain slices and dissociated cell cultures at high spatiotemporal resolution, which is attractive for neuroscience. Since the HDMEA enables to record the activity of single neurons at sub-cellular resolution, a combination with intracellular recording techniques, such as patch clamp, will allow for new in vitro experiments. Such combination technique requires precise localization of both the cell of interest and the glass micropipette (GM) with respect to the HDMEA. Here, we present a methodology to locate the three-dimensional (3D) position of a GM on the HDMEA without the use of an optical microscope. For the (x, y) position, the achieved accuracy is (±2μm, ±5μm), which is less than the electrode pitch of 18μm. For the z-position, the obtained accuracy is ±2μm for distances of 5-50μm between the GM tip and the HDMEA surface. We also observed that variations in size of GM tips and HDMEA electrodes have minimal effects on the blind localization performance. This approach shows the feasibility of automated navigation of a GM atop the HDMEA to patch a single cell in vitro.