Design of automatic histological processing equipment for biological samples for teaching use in educational laboratories

Abstract

This article presents the development of an automatic histological processing machine, which was designed and built for educational use at a low cost. The architecture combined STM32F401 microcontrollers, PID controllers, DS18B20 temperature sensors, bipolar stepper motors, and a Nextion touchscreen to automate the dehydration, impregnation, and inclusion of biological samples. A robust mechanical structure made of stainless steel was designed along with an electronics-based distributed master-slave control system, in accordance with UART communication and monitoring by inductive sensors and limit switches. The performance of the prototype was evaluated using an observation sheet with 10 criteria that were validated in content and appearance by expert judgment. Average values between 3.71 and 4.22 of a maximum possible score (5) were obtained, indicating consistent thermal control, motion repeatability, stability in motion, as well as smoothness, while motor accuracy was automatically calculated. The device is a viable and replicable alternative to commercial systems, providing access to educational technologies in biomedical sciences and bolstering hands-on training for students at universities.