Portable stand-alone instrumentation for intracellular in vitro recordings

A portable stand-alone system for continuous intracellular recordings in vitro is presented here. An off-the-shelf operational amplifier is used to illustrate the feasibility and reliability of the proposed method. The amplifier is powered by two coin batteries and directly connected to a traditional intracellular glass electrode. The brain of the sea slug Tritonia diomedea is used as the experimental model. By simultaneously impaling one neuron using two electrodes, and recording with two independent systems, namely, a commercial intracellular amplifier and the portable stand-alone circuit, intracellular signals are acquired for more than 20 hours without affecting cell spontaneous spiking patterns. The implemented system presents signal-to-noise ratio higher than 30. Signals recorded with the stand-alone circuit are shown to reliably reproduce subthreshold activity after a second order low-pass filter stage. Possible applications for this system include multichannel intracellular MEMS-based arrays and portable implantable electronics for drug-delivery.