Robotic Patch Clamp Based on Noninvasive 3-D Cell Morphology Measurement for Higher Success Rate

The formation of the gigaseal, a giga Omega-scale seal between the micropipette electrode and cell surface, is the keystone to measure the extremely weak electric signals of cell ion channels in patch clamp technique. To determine a point on the cell surface facilitating gigaseal formation, 3-D cell morphology information is required. However, the current 3-D cell morphology measurement methods relying on special devices or easily causing clogging issues of the micropipette electrode due to contact on cells are usually not applicable in the traditional patch clamp system. Addressing this, a noninvasive 3-D cell morphology measurement method was developed in this article for robotic patch clamp with a higher success rate of gigaseal formation. First, the measured bath impedance of the micropipette electrode was modeled and then utilized to measure the cell surface height noninvasively. Using the measured cell surface heights at key positions, the 3-D cell morphology was fitted to determine a contact position on the cell surface to facilitate gigaseal formation. Finally, a robotic whole-patch clamp process was conducted at the determined contact position. Experimental results demonstrated that 100% and 90% success rates of noninvasive 3-D cell morphology measurements were achieved on the cultured human embryonic kindey (HEK)-293 cells and pyramidal neurons in mouse brain slices, respectively, with an average measurement error of cell surface height less than $0.15~\mu \text{m}$ . At the determined contact position, significant improvements in success rates of gigaseal formation and whole-cell patch clamp operation were achieved in comparison to the results at the positions recommended in related work. Our research may spike inspiration to improve the success rates of gigaseal formation and patch clamp operation based on 3-D cell morphologies.