A Hall Effect sensor based syringe injection rate detector

Rate of injection of anesthesia affects various physiological and pathological changes in a patient such as perception of pain and time taken for onset of akinesia. A training system based on a suitably modified syringe equipped with a simple measurement system where a trainee can observe the rate of injection, prior to practicing on live patients, can be of immense value towards reducing the risks involved. In this paper, we propose a low-cost Hall Effect sensor based measurement scheme for detection of rate of injection from a syringe. The Hall Effect sensor along with a permanent magnet senses the position of the syringe piston relative to the syringe body. A new design of a suitable piston has been discussed that minimizes anesthesia wastage by providing the illusion of anesthesia flow through the needle. A prototype system has been built and tested that validated the new scheme. The rate of injection was measured and displayed in real time. It was within acceptable error limits demonstrating the usefulness of the system for practical training purposes.