A Fully Digital Implementation of Voltage, Current, and Dynamic Clamping Methodologies

Abstract

Standard electrophysiology experiments utilize a technique known as voltage clamping: the surface of the cellular membrane is held constant, or clamped, which allows the researcher to study the membrane permeability and ion exchange. This process is usually performed with commercially available analog equipment. While analog circuitry provides an accurate and reliable equipment medium, it does not allow for much in the way of real-time data processing. Additionally, there is the issue of data acquisition which must be performed using an analog to digital converter (A/D). A need exists to resolve these issues in one device. The Universal Clamp, a patent pending electronic device designed and built by Dr. Jiang Wu at the University of Rhode Island, addresses this need. The Universal Clamp, however, does much more than data acquisition (DAQ) and signal processing. As the name implies, it has the capability of performing voltage clamping, current clamping, and dynamic clamping, all in one device, with the aid of a digital signal processing (DSP) chip. This functionality provides researchers greater flexibility in the types of experiments they can conduct, as well as simplifying current standard methodologies. Using the visceral ganglion from Aplysia californica, the Universal Clamp has successfully performed voltage clamping, current clamping and dynamic clamping, while simultaneously executing data acquisition and signal processing algorithms.