Development of a digital amplifier system for cut-open oocyte electrophysiology

The cut-open oocyte Vaseline gap technique is a powerful electrophysiological method for the characterization of ion channels. However, traditional amplifiers for cut-open oocyte Vaseline gap are labor intensive and require significant user expertise. We introduce an innovative, open-source digital amplifier system with high-speed digitization and software-controlled electronics for computer-driven automation. This system compares well to existing commercial systems in terms of conventional specifications of step response (current peak at 25μs and decay of 36μs time constant), current noise (1.0 nA at 3-kHz bandwidth), and dynamic range (96.9 dB). Additionally, it unlocks new methods through close integration of the amplifier and software, including machine-learning techniques for tuning capacitive compensation waveforms, achieving a 100-fold suppression of mean-squared transient current, and impedance measurement methods to identify system components such as membrane capacitance and electrode resistances. For future extensions, the design has unique attributes such as real-time digital signal processing for feedback, multiple input and multiple output, and allows for user customization. By providing open-source access to the circuit board designs, control software, and field-programmable gate array code on GitHub, this approach aims to foster cross-disciplinary collaboration and facilitate instrument customization enabling previously inaccessible electrophysiology experiments.