Fig. 7: Challenging the controller in situ for real-time endpoint detection.

a Experimental setup for testing cold atmospheric plasma (CAP) real-time endpoint detection. The sensor was submerged horizontally in phosphate-buffered saline (PBS) evenly distributed on a glass slide. This positioning was used to minimize direct CAP interaction with the sensor. b Live H₂O₂ wire sensor measurements during plasma treatment of a 500 µL PBS solution with voltage held constant. Concentration data (solid line) is displayed during CAP treatment at 20 kV, until the targeted concentration level (dashed line) is reached. c The time at which the plasma device is activated (1) and deactivated (0) is tracked over the course of the treatment protocol. The microcontroller actively evaluates every 20 s whether the previous result sampled is at or above 40 µM, at which point the CAP pulsed signal is automatically halted until a new concentration level is selected for a following treatment cycle.