Non-invasive method and device for judging changes in human blood glucose

Abstract

A non-invasive method and apparatus for determining changes in human blood glucose levels, comprising: (1) providing a heating element to heat a target skin area of ​​the human body; the power range of the heating element is 0.5W to 2W, the heating time is 30 seconds to 120 seconds, and the heating temperature is 38 to 40 degrees Celsius; (2) providing a temperature sensing element to measure and record the temperature changes of the target skin area during heating and after heating is stopped; (3) providing a microcontroller to analyze the temperature changes of the target skin area to determine the change in the heat capacity of the target skin area; (4) the microcontroller determines the change in blood glucose concentration based on the trend of the change in the heat capacity of the target skin area; when the heat capacity decreases, it is determined that the blood glucose concentration increases, and when the heat capacity increases, it is determined that the blood glucose concentration decreases.

Description

Non-invasive method and device for judging changes in human blood glucose This invention relates to a non-invasive method for determining blood glucose changes, particularly a technique that uses the measurement of changes in the heat capacity of local tissues in human skin to determine changes in blood glucose levels. Traditional blood glucose monitoring methods are mainly divided into two types: invasive and non-invasive. Invasive methods require blood to be drawn through a needle. They are highly accurate, but have drawbacks such as pain, infection risk, and high cost of consumables. Non-invasive methods mainly rely on optical or electrochemical technologies, such as near-infrared spectroscopy and laser technology. Although these methods do not require blood to be drawn, they are easily affected by external factors such as skin color, skin thickness, and sweat, and the equipment costs are relatively high. To address the aforementioned problems, this invention provides a non-invasive method for determining changes in human blood glucose levels, which determines blood glucose levels by measuring changes in local heat capacity of the human skin. Technical features of this invention: A non-invasive method for assessing changes in human blood glucose levels includes the following steps: A heating element is provided to heat a target area of ​​human skin; the power range of the heating element is 0.5W to 2W, the heating time is 30 seconds to 120 seconds, and the heating temperature is 38 to 40 degrees Celsius. A temperature sensing element is provided to measure and record the temperature change of the target skin area during heating and after heating is stopped; A microcontroller is provided to analyze the temperature change in order to determine the change in heat capacity of the target skin area; The microcontroller determines the change in blood glucose concentration based on the trend of heat capacity change in the target skin area; when the heat capacity decreases, it determines that the blood glucose concentration increases, and when the heat capacity increases, it determines that the blood glucose concentration decreases. A non-invasive device for judging changes in human blood glucose levels, comprising: A heating element for heating a target skin area of ​​the human body, the heating element having a power range of 0.5W to 2W, a heating time of 30 seconds to 120 seconds, and a heating temperature of 38 to 40 degrees Celsius; A temperature sensing element is used to measure and record the temperature change of the target skin area during heating and after heating is stopped; A microcontroller analyzes the temperature change to determine the trend of heat capacity change in the target skin area, and judges the change of blood glucose in the human body based on the trend of heat capacity change; when the heat capacity decreases, it is judged that the blood glucose concentration increases, and when the heat capacity increases, it is judged that the blood glucose concentration decreases. A carrier for supporting the heating element, the temperature sensing element, and the microcontroller. Efficacy of this invention: This invention requires no skin puncture or blood sampling, making it a non-invasive and painless test. It completely avoids the pain, infection risk, and psychological burden of traditional invasive blood glucose testing, making it especially suitable for children, those who need frequent monitoring, and patients who are afraid of needles. Based on the difference in specific heat capacity between glucose and water (glucose: 1.2 kJ / (kg·K), water: 4.18 kJ / (kg·K)), blood glucose fluctuations can be indirectly inferred by the rate of skin temperature change during and after heating. This method breaks through the limitations of traditional optical or electrochemical techniques and provides a completely new approach to measuring physiological parameters. Experimental data from this invention show that changes in blood glucose concentration significantly affect blood heat capacity. For example, in a fasting state, blood heat capacity is stable, and skin temperature changes gradually. After glucose ingestion, blood heat capacity decreases significantly, and skin temperature changes drastically. This difference in skin temperature change can distinguish fluctuations in blood glucose levels. Using common components such as thermistors (NTC) and low-power heaters, the device is designed for low cost and low power consumption, with a cost far lower than that of optical sensors or electrochemical chips. The support component is made of heat-insulating material, which can reduce the impact of the external environment on skin temperature, and the measurement is carried out in areas with stable blood flow, such as the inner side of the wrist, to improve the reliability of the data. It is unaffected by skin color, skin thickness, or sweat, and is suitable for diverse populations. It can be integrated into wearable devices such as smart bracelets and patches, and paired with wireless transmission (Bluetooth / Wi-Fi) and a mobile APP to achieve continuous monitoring and remote health management. No test strips, needles, or chemical reagents are needed, significantly reducing long-term usage costs. Users only need to wear the device and start the detection; the whole process is automated and suitable for home or daily health management. 10: Bearing components 20: Heating element 30: Temperature sensing element 40: Microcontroller [Figure 1] A graph showing the skin temperature measured by a thermistor under sugar-consuming and sugar-free conditions according to the present invention. [Figure 2] A graph showing the skin temperature measured by thermocouples in the present invention under sugar intake and sugar-free conditions. [Figure 3] A curve showing the return to normal skin temperature measured by thermocouples under sugar intake and sugar-free conditions according to the present invention. [Figure 4] Block diagram of the device of the present invention. Specific heat capacity (SHC) is a physical quantity used to describe the ability of a substance to change temperature when it absorbs or releases heat. Specifically, SHC is defined as the amount of heat required for a unit mass of a substance to increase or decrease its temperature by 1 degree Celsius (or 1 Kelvin). Its mathematical expression is: c = Q / mΔT. Where c is the specific heat capacity, usually expressed in joules per kilogram per degree Celsius (J / (kg·℃)) or joules per kilogram per Kelvin (J / (kg·K)). Q is the amount of heat absorbed or released, expressed in joules (J). m is the mass of the substance, expressed in kilograms (kg). ΔT is the temperature change, expressed in degrees Celsius (℃) or Kelvin (K). A substance with a higher specific heat capacity will experience smaller temperature fluctuations when absorbing the same amount of heat; conversely, a substance with a lower specific heat capacity will experience larger temperature fluctuations. Regarding the difference in specific heat capacity between glucose and water: The specific heat capacity of water is approximately 4.18 kJ / (kg·K), meaning that 1 kilogram of water requires 4.18 kilojoules of heat to raise its temperature by 1°C. The specific heat capacity of glucose is approximately 1.2 kJ / (kg·K), much lower than that of water, meaning that glucose experiences a greater temperature rise when absorbing the same amount of heat than water. The reason for this difference is presumably due to their different molecular structures. Water molecules (H... Water molecules (C₂O) are polar and have strong intermolecular hydrogen bonds, which means that water molecules require more energy to change their state of motion (i.e., the temperature change is smaller). Glucose (C₂O) 6H 12 O 6) is an organic molecule with weak intermolecular forces, so when it absorbs the same amount of heat, the temperature change is more pronounced. Human blood is mainly composed of two parts: plasma (55%) and blood cells (45%). Plasma is primarily water (approximately 90-92%). Blood cells include erythrocytes, leukocytes, and platelets, with water content of approximately 60-70%, 70-80%, and 70%, respectively. Therefore, the main component of blood is water. When glucose is added to the blood, the blood's specific heat capacity changes, directly affecting skin temperature. Based on the above principle, this invention applies the difference in specific heat capacity between glucose and water to determine blood sugar levels. The present invention provides a non-invasive method for determining changes in human blood glucose levels, comprising the following steps: A heating element is provided to heat a target area of ​​human skin; the power of the heating element is in the range of 0.5W to 2W, the heating time is from 30 seconds to 120 seconds, and the heating temperature is from 38 degrees Celsius to 40 degrees Celsius. A temperature sensing element is provided to measure and record the temperature change of the target skin area during heating and after heating is stopped; A microcontroller is provided to analyze the temperature change in order to determine the change in heat capacity of the target skin area; Based on the trend of this heat capacity change, the change in blood glucose level can be determined; when the heat capacity decreases, the blood glucose concentration is determined to increase, and when the heat capacity increases, the blood glucose concentration is determined to decrease. The heating element includes, but is not limited to, resistance heating elements, micro heating elements, thermoelectric materials, and infrared heating elements. The temperature sensing element includes, but is not limited to, a thermistor, a negative temperature coefficient thermistor (NTC), a platinum resistance temperature sensor (PT100), or a thermocouple. The target skin area is the inside of the wrist, the arm, or other skin surfaces. The method can be integrated into a smart wearable device to achieve continuous, non-invasive blood glucose monitoring. The method transmits data to external devices (such as mobile apps or cloud platforms) via wireless transmission technologies (such as Bluetooth or Wi-Fi) and provides real-time alerts for changes in blood glucose levels using visual or auditory signals. In the experiments of this invention, it is assumed that the heat conduction of the target skin area is uniform, and the temperature change can be described by equation (1): Equation (1): Q = mcΔT Where Q: Heat provided by the heater (J). m: Equivalent mass of the tissue (g). c: Specific heat capacity of the tissue (J / g·K). ΔT: Temperature change (unit: degrees Celsius, °C). If the heater provides heat at a stable power P, as in equation (2) Equation (2): Q = P. t Where P: heating power (W, 1W = 1J / s). t: heating time (s). Combining equations (1) and (2), we obtain equation (3): Equation (3) P. t=mcΔT This means that in the experiment, we can indirectly calculate the skin's heat capacity C by measuring P, t, and ΔT, as shown in equation (4). Equation (4) C=(P.t) / (mcΔT) The relationship between skin heat capacity C and blood glucose concentration is shown in equation (5). Equation (5) Q=C. ΔT Where Q: Heat provided by the heater (unit: joules, J). C: Heat capacity of skin tissue (unit: joules per degree Celsius, J / ℃). ΔT: Temperature change (unit: degrees Celsius, ℃). According to equation (5), in the non-invasive blood glucose monitoring method of the present invention, the heat capacity C of skin tissue is a key parameter. Since the specific heat capacity of glucose (1.2 kJ / (kg·K)) is lower than that of water (4.18 kJ / (kg·K)), when blood glucose concentration increases, the proportion of glucose in the blood increases, leading to a decrease in the heat capacity C of skin tissue. A decrease in heat capacity C results in a faster temperature rise ΔT under the same heating amount Q. Conversely, when blood glucose concentration decreases, the temperature rise is slower. As shown in Figure 1, the heating element heats the skin for 30 seconds to a temperature of 40 degrees Celsius. The target skin area is the inside of the wrist. Temperature changes in the target skin area are continuously monitored during heating and after heating is stopped. A negative temperature coefficient thermistor (NTC) is used as the temperature sensing element to measure skin temperature. The smaller the resistance in Figure 1, the higher the temperature of the target skin area. The experimental results showed that when blood sugar did not increase (two fasting periods), due to the heat capacity of water in the blood, the skin temperature hardly increased after 90 seconds. The resistance value decreased from the initial 6.35Ω to 6.23Ω (90 seconds) and 6.25Ω (90 seconds), with a small decrease, indicating that the heat capacity of the target skin area was stable and the temperature rise was gradual. After 90 seconds, the temperature of the target skin area gradually returned to the normal skin temperature (the resistance gradually increased, with a small increase). However, after sugar intake (drinking 300cc of cola three times), due to the thermal properties of glucose in the blood, the skin temperature hardly increases after 90 seconds. The resistance drops from the initial 6.35Ω to 6.15Ω (90 seconds) and then to 6.14Ω (90 seconds). The large drop in resistance indicates a significant temperature rise in the target skin area, and the skin temperature quickly returns to normal after 90 seconds (rapid increase in resistance). The large difference between the decrease and increase in resistance indicates that the target skin area heats up and cools down quickly, resulting in a large change in the thermal capacity of the target skin area. This is because the increase in blood glucose causes a decrease in the blood's specific heat capacity. The above experiments show that the change in blood glucose levels can be determined by judging the trend of heat capacity change (temperature change) in the target skin area. Figure 2 shows the experimental results of sensing skin temperature changes using thermocouples. In the experiment, the heating element heated the target skin area for 120 seconds and then stopped, recording the temperature recovery process. In the figure, the voltage represents skin temperature; the higher the voltage, the higher the temperature. Before drinking cola, the temperature recovery curve was flat. Ten minutes after drinking cola, blood sugar had not yet risen significantly, and the temperature recovery curve was similar to that before drinking cola, also flat. Thirty minutes after drinking cola, blood sugar rose significantly, and the temperature recovery curve became significantly steeper, with a greater slope than before drinking cola, indicating a faster temperature recovery rate. Figure 3 shows the normalized results of skin temperature recovery using thermocouple sensing. In the experiment, the heating element heated the target skin area for 120 seconds and then stopped, recording the temperature recovery process. In the figure, voltage represents skin temperature; higher voltage indicates higher temperature. Blood glucose is lowest upon waking in the morning, and the temperature recovery curve is flat. 30 and 60 minutes after drinking cola, blood glucose rises significantly: the temperature recovery curve is noticeably steeper, with a greater slope than before drinking cola, indicating a faster temperature recovery rate. 90 and 120 minutes after drinking cola, blood glucose decreases slowly, and the temperature recovery curve is more gradual than at 30 and 60 minutes. As shown in Figure 4, the non-invasive human blood glucose change judgment device prepared based on the above method and experiment includes: a heating element 20, a temperature sensing element 30, and a microcontroller 40 integrated on a carrier 10. The carrier 10 includes thermal insulation material to reduce interference from ambient temperature. The carrier 10 may also be a patch or a wearable device. The heating element 20 is used to apply constant power heating to the target skin area; the power range of the heating element 20 is 0.5W to 2W, and the heating time is 30 seconds to 120 seconds. The heating element 20 is selected from at least one of the following: resistance heating element, micro heating element, thermoelectric material, infrared heating element. The temperature sensing element 30 is used to sense temperature changes in the target skin area. The temperature sensing element 30 is an NTC (negative temperature coefficient temperature sensing element), a PT100 (platinum resistance temperature sensor), or a thermocouple. The microcontroller 40 is electrically coupled to the heating element 20 and the temperature sensing element 30, and is used to control the heating power and record temperature data. The target skin area is the inside of the wrist, the arm, or other skin surfaces. In summary, when the proportion of glucose in the blood increases (high blood sugar), the overall specific heat capacity of the blood decreases, resulting in a rapid increase in skin temperature when heated to a constant power. Conversely, when the proportion of glucose in the blood decreases (normal or slightly low blood sugar), the overall specific heat capacity of the blood increases, resulting in a slow increase in skin temperature when heated to a constant power. Therefore, by measuring the trend of local skin temperature fluctuations, changes in blood glucose concentration can be directly determined. Large fluctuations in skin temperature indicate an increased proportion of glucose in the blood; conversely, small fluctuations indicate a normal proportion of glucose in the blood. It should be noted that this invention does not directly convert skin temperature into blood glucose concentration. This invention provides a judgment result: when skin temperature fluctuates significantly, it can be judged that the proportion of glucose in the blood is high. In this case, the subject should be vigilant and have a blood sample taken to measure the actual blood glucose level. In summary, this invention, based on the innovative principle of heat capacity detection and combined with low-cost components and intelligent analysis, provides a painless, highly sensitive, and interference-resistant non-invasive blood glucose monitoring solution. Breaking through the limitations of traditional technologies, it can be widely applied to diabetes management, exercise physiology monitoring, and daily health tracking, possessing significant market competitiveness and social value.

Claims

1. A non-invasive method for determining changes in human blood glucose includes the following steps: (1) providing a heating element to heat a target skin area of ​​the human body; the power range of the heating element is 0.5W to 2W, the heating time is 30 seconds to 120 seconds, and the heating temperature is 38 degrees Celsius to 40 degrees Celsius; (2) providing a temperature sensing element to measure and record the temperature change of the target skin area during heating and after heating is stopped; (3) providing a microcontroller to analyze the temperature change to determine the change in heat capacity of the target skin area; (4) the microcontroller determines the change in blood glucose concentration based on the trend of the change in heat capacity of the target skin area; when the change in heat capacity decreases, it is determined that the blood glucose concentration increases, and when the change in heat capacity increases, it is determined that the blood glucose concentration decreases. The non-invasive method for determining changes in human blood glucose levels as described in claim 1, wherein, The heating time is 30 seconds, and the heating temperature is 40 degrees Celsius. The non-invasive method for determining changes in human blood glucose levels as described in claim 1, wherein, The target skin area is the inside of the wrist and the arm. The non-invasive method for determining changes in human blood glucose levels as described in claim 1, wherein, This method can be integrated into a smart wearable device to monitor continuous blood glucose fluctuations. A non-invasive device for judging changes in human blood glucose levels, comprising: A heating element for heating a target skin area of ​​the human body, the heating element having a power range of 0.5W to 2W, a heating time of 30 seconds to 120 seconds, and a heating temperature of 38 degrees Celsius to 40 degrees Celsius; a temperature sensing element for detecting temperature changes in the target skin area; a microcontroller for measuring and recording temperature changes in the target skin area during heating and after heating is stopped, analyzing the temperature changes to determine the trend of heat capacity change in the target skin area, and determining the change in blood glucose levels based on the trend of heat capacity change; when the heat capacity change decreases, it is determined that the blood glucose concentration is rising, and when the heat capacity change increases, it is determined that the blood glucose concentration is falling; a carrier for supporting the heating element, the temperature sensing element, and the microcontroller. The non-invasive human blood glucose change determination device as described in claim 5, wherein, The target skin area is the inside of the wrist. The non-invasive human blood glucose change determination device as described in claim 5, wherein, The carrier may include an insulating material, a patch, or a wearable device. The non-invasive human blood glucose change determination device as described in claim 5, wherein, The temperature sensing element is a thermistor or a thermocouple.

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