Fabrication and evaluation of a thermal flowmeter for human respiration

Purpose This paper aims to design and fabricate a flowmeter based on temperature difference measurement that can examine human breathing, and the fabrication method and final product are quite cheap compared to previous examples. Design/methodology/approach The electrical circuit based on Wheatstone-Bridge and devices used to build this sample are simple that is used as a thermoelectric sensor, but its geometric shape is designed based on accurate simulations and creativity, such that its output is very suitable, high-quality and accurately reflects the breathing of the person being tested. Findings The simulation results are explained in the paper to select the appropriate geometric shape and size. Also, after fabrication and calibrating the prototype, the display output shape for the flow applied to the input of this sensor is shown in the results section. The results showed that the measurement error of the manufactured flowmeter in the range of 45–85 mmHg is less than 3%. Originality/value Images of the fabricated prototype demonstrate the simplicity of the proposed design and its originality. The low-cost fabrication process and simple design of this design, along with low-error measurements, introduce this proposed flowmeter as a novel and practical design.