Virtual instrument for experimental studies in biological systems

Biological tissues, especially excitable cells, may have their biophysical properties altered under adequate stimulation. To better understand the interactions between biological tissues and stimuli with different energy modalities, it is necessary to precisely control the generation of the stimulus and the temporal parameters of its application, and to synchronize its delivery with the acquisition of the biological signal of interest. The objective of the present work is to present a virtual instrument (VI) developed to control the shape and timing of the delivered stimulus to tissues in vitro and simultaneously acquire the biological signal. For stimuli delivered by electronic devices, the system controls the programmable waveform generator and the data acquisition board (DAQ) via the universal serial bus (USB) communication interface used to capture the biological signal. The LabVIEW® development platform was used to build the graphical interfaces for controlling all stimulation and acquisition parameters. The graphical interface has three modules: 1) the configuration module of the stimulus generation and application includes a table where each sequence of stimulation parameters can be inserted individually or in batch; 2) the acquisition module, consisting of a screen that displays in real time the acquired signals during the experiment, and a field to enter addresses to save the acquired data to files; 3) the post-processing module, which includes a set of statistical analysis tools, frequency analysis, and digital filtering. Both the biological signal of interest and the synchronization signal for stimulation are recorded in the files. The developed VI can be applied in the study of stimulation of virtually any kind of biological preparation. This system was applied to the study on the effects of high power ultrasound on the heart.