FPGA-based plasma sterilization device for wound-edge recognition

There is a currently a lack of large-area plasma sterilization devices that can intelligently identify the shape of a wound for automatic sterilization. For this reason, in this work, a plasma sterilization device with wound-edge recognition was developed using a field-programmable gate array (FPGA) and a high-performance image-processing platform to realize intelligent and precise sterilization of wounds. SOLIDWORKS was used to design the mechanical structure of the device, and it was manufactured using 3D printing. The device used an improvement of the traditional Sobel detection algorithm, which extends the detection of edges in only the x and y directions to eight directions (0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°), completing the wound-edge detection by adaptive thresholding. The device can be controlled according to different shapes of sterilization area to adjust the positioning of a single plasma-jet tube in the horizontal plane for two-dimensional movement; the distance between the plasma-jet tube and the surface of the object to be sterilized can be also adjusted in the vertical direction. In this way, motors are used to move the plasma jet and achieve automatic, efficient, and accurate plasma sterilization. It was found that a good sterilization effect could be achieved at both the culture-medium level and the biological-tissue level. The ideal sterilization parameters at the culture-medium level were a speed of 2 mm/s and a flow rate of 0.6 slm, while at the biological-tissue level, these values were 1 mm/s and 0.6 slm, respectively.