Fig. 2.

Design iterations for dual-port lick detectors. A: the single-port optical lick detector design (top), and implementation during behavioral experiments (bottom). Scale bar indicates 8-mm opening. Elastomer isolates circuitry from silicone tubing dispensing water. B: first iteration of dual-port design (top). Detectors had a 5-mm opening and were mounted on an acrylic base for variable angle and vertical positioning of sensors (bottom). C: final design (top) further optimized after testing with mice. Detectors were widened to 8-mm opening, and 3D-printed base was customized to have a smaller footprint and an optimal fixed angle (120°) between detectors. D: expanded view of detector in C, showing position of infrared (IR) beam and spout.