Tools for physiology labs: inexpensive equipment for physiological stimulation

We describe the design of inexpensive equipment and software for physiological stimulation in the neurobiology teaching laboratory. The core component is a stimulus isolation unit (SIU) that uses DC-DC converters, rather than expensive high-voltage batteries, to generate isolated power at high voltage. The SIU has no offset when inactive and produces pulses up to 100 V with moderately fast (50 μs) rise times. We also describe two methods of stimulus timing control. The first is a simplified conventional, stand-alone analog pulse generator. The second uses a digital microcontroller interfaced with a personal computer. The SIU has performed well and withstood intensive use in our undergraduate physiology laboratory. This project is part of our ongoing effort to make reliable low-cost physiology equipment available for both student teaching and faculty research laboratories.