For a bio-sensing laboratory, we developed a compact-size process controller. The unit can be carried along together with the experimental setup in the size of a briefcase.
The device controls the temperature of an acoustic-wave transmission line by means of a thermoelectric heat pump as well as the flow of liquids through the experimental setup with a peristaltic micropump. At the same time, data is collected using a portable network-analyzer unit and displayed to the user through a browser-based user interface, provided wirelessly to a tablet or mobile phone by an embedded web server and Wi-Fi access point operating inside the process controller.
The Process Controller was customized especially to suit the Peltier unit, the micropump and the network analyzer used in the experiment. The software is based on GNU/Linux and the hardware is based on the well-known Raspberry Pi single-board computer and the Arduino microcontroller, which allows for a wide range of adaptions or modifications later on, in case the experimental setup changes.
To accelerate the prototyping of the device, we produced the printed circuit board (PCB) in-house with the use of computer numerical control (CNC). The footprint of the assembled unit was reduced to match that of the single-board computer by employing surface-mounted devices (SMD).