The main forms of heat dissipation of the human body are radiation, convection, and evaporation. The overall heat radiation and convection can be calculated by the environmental temperature and the radiation temperature, while heat evaporation can be calculated by the environmental humidity and the finger surface humidity.
A revised heat transmission method is applied in this product to determine the blood flow velocity. A heat transfer bar with thermistors on both ends contacts the skin of the finger with one end, so the temperature change of the bar can be measured. Meanwhile, an infrared radiation temperature sensor is used to take the temperature of the finger surface. These values are combined to calculate the blood flow velocity.
The photoelectric method is adopted to determine the parameters of oxygen saturation and haemoglobin concentration. The surface of the finger is exposed to infrared light of a specific wave length in an assigned sequence and the light intensity penetrating the finger is detected. Based on the change of light intensity, the required parameters are calculated. Considering that the heat dissipating capacity cannot represent the local metabolic heat, the latter is then corrected by core temperature, dressing impedance and blood flow volume. The blood glucose value of the metabolic heat integration method can be calculated by local metabolic rate, blood flow volume, haemoglobin concentration, oxygen saturation and corrected value of blood glucose. The blood glucose value of the infrared method is calculated from photoelectric signals and the haemoglobin concentration. By combining the blood glucose values of the two methods, the blood glucose concentration in the human body is obtained.
This product integrates various of sensors for signal collection, a processing circuit for signal conversion and amplification, a microprocessor to calculate the values of the parameters (blood glucose concentration, oxygen saturation, haemoglobin concentration, blood flow volume, pulse, ambient temperature and humidity, and shell temperature and humidity), and finally displays the results.