Fig. 3.

Microfluidic device characterization. (a) Schematic depicting protocol for generating brief neurotransmitter pulses. A modified 3-channel device (not to scale) is shown in the starting position (left) with the recording pipette positioned in the high osmolarity (HIGH) fluid stream. With a single lateral movement of the device (black arrow), the recording pipette is exposed briefly to the low osmolarity (LOW) stream and then to the second high osmolarity stream (right). (b) Representative open-tip liquid junction currents obtained using the protocol in Panel A using devices with different central channel widths. Pulse durations for these currents were 410, 810, and 1620 μs (for the 10, 25, and 50 μm central channels, respectively). (c) Relationship between central channel width and pulse duration. The data were fit using a linear regression (see Section 3; r² = 0.99). Although not always visible, error bars representing the S.E.M. were included for all points.