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Here you can find infos on the pacer, assembly and usage instructions.
The documentation is definitely not perfect, if something is missing or unclear, feel free to get in touch!
By following these instructions, you can build a pacing unit (= the box in the picture above), capable of outputting biphasic pulses (see below for an exemplary waveform of pulses at 1 Hz, 5 V amplitude and 50 ms pulsewidth with negative polarity of the first pulse). The unit provides the output of 4 signals, out of which 2 signals share the same waveform. You can grab these signals either directly from pinheaders on the pcb, or connect an additional Connectorboard via a flat ribbon cable which offers an interface to arbitrarily connect wires with alligator clips for contacting your samples (build instructions also included).
The pacing unit was designed for a beginner-friendly assembly, making use of only several basic hand-solderable components. Its purpose is pacing multiple tissues in cardiac Organ-on-Chip systems with biphasic pulses of varying frequencies.
The circuit is based on an Arduino Nano which controls a display and rotary encoder as user interface. The Arduino controls a DAC which is able to provide 2 independent 0-5 V signals (DAC1 & DAC2). These signals are further converted by an OpAmp in differential amplifier configuration to an output range of ~ -12.7 - 12.7 V. Each DAC-Output is connected to two OpAmp inputs, resulting in two independent outputs (with the same waveform): DAC1 -> S1/S2, DAC2 -> S3/S4. A DC/DC converter provides the OpAmp supply voltages of +- 15 V and is able to deliver up to 66 mA.
