Portable Embedded System for Continuous Monitoring of Anaesthetics

The anesthesia covers a fundamental role in the success of surgical medical operation and not only. The evolution of medicine has led to the definition of specific and custom anesthetic therapy according to the body response of the patient, to minimize the risk and to avoid pains or unexpected reactions. We propose a portable, low power and low-cost solution to cope this challenge, obtaining a device able to continuously monitor the drugs concentration in the patient’s blood. The device is a custom Printed Circuit Board (PCB) designed to measure the RedOx current flow in an electrochemical sensor for anesthetics. A micro-controller, generates a Pulse Width Modulation (PWM) (similar digital) signal to drive the electrochemical cell. The front-end circuit translates the current in a quasi-digital, event-based signal to communicate with the microcontroller. The event-based approach leads to a reduction in power consumption with respect to other solutions such as AD converter. The PCB management of the data is based on ARM® Cortex®-M4 32-bit processor mounted on the board and the transmission of the information is implemented by the Bluetooth® 5 Low Energy protocol exploiting an antenna printed on the board. The device allows a wireless communication up to eighteen meters and low power consumption during the working step. Finally, a user-friendly custom graphic interface is implemented to provide all the useful tools for the connection and the data elaboration. Thanks to the reduced dimensions of the device (91.42 mm x 16.82 mm) the full system fits in a pen allowing a portable employment for the anesthesiologist in different working conditions.