Characterizing the Sources of Current Generated by a Membrane-Based Hair Cell Sensor

Recently, researchers have developed a method to construct a membrane-based hair cell sensor that generates a measurable current in response to physical disturbance of the hair. Representing the cell membrane, a phospholipid bilayer is formed at the interface of two lipid-encased hydrophilic volumes and a hair is located in a center of one of the volumes act a shaking element. In this work, we study the current generated by free vibration of the hair in a revised hair cell embodiment that uses a hair that is physically supported by the surrounding substrate. The current generated by the sensor is measured by a patch clamp amplifier, and the net charge displaced across the membrane during motion of the hair is computed. Experiments performed with a complete hair cell sensor and various control cases that lack a bilayer indicate that the current measured at 0mV applied across the membrane is due to vibration of the positive electrode that changes the local electromagnetic field. Experiments conducted with both geland liquid-supported membranes indicate that gel-supported membranes have a higher sensitivity of (0.066 pC/mV) than liquid-supported membranes (0.015 pC/mV) as the applied voltage increases. Lastly, the motion of the tip of the hair is imaged using a high-speed camera. This test shows that the hair oscillates at the same frequency observed in the measured current traces, which indicates that transverse bending of the bilayer is the cause for the time rate of change in capacitance in the membrane that produces a voltage-dependent current.