Fig. 2.

Microfluidic device design and integration for electrophysiological recording. (a) Standard 3-channel design (length not to scale). Individual channels (black) are 100 μm wide and separated by 50 μm septa (white) that taper to a final thickness of 10 μm. The circular enlargements at the origin of each channel (top) permit solution access via polyethylene tubing. (b) Modified 3-channel design for application of synaptically relevant agonist pulses. Dimensions are identical to those of the standard 3-channel device except for the width of the central channel, which tapers to a final width of 10 μm. (c) Schematic of the experimental setup. PDMS devices were connected to a stepper motor via an acrylic platform, allowing for translation of parallel solution streams across a stationary recording electrode. (d) Top-down view of a modified 3-channel microfluidic device (black arrows indicate device septa) and recording electrode (indicated by asterisk, *) submerged in bath solution, as typically arranged for electrophysiological recordings. Outer and central channels are shown delivering high and low osmolarity solution streams, respectively, allowing for visualization of solution interfaces (white arrows). Note that channels were ~80 μm high, though they appear smaller due to the image perspective.