A research group led by Professor Riki Nakamura of Tohoku University, in collaboration with the Microsystem Fusion Research and Development Center, has developed a tablet-sized "drinking thermometer" that operates with gastric acid power generation, and succeeded in animal application experiments.
Basal body temperature at rest, core body temperature and its rhythm (body clock) are important indicators for grasping the state of health.These are difficult to measure with a general thermometer and have a large error.The method of measuring rectal temperature by inserting a temperature sensor into the anus can measure core body temperature accurately and easily, but it is difficult to carry out on a daily basis.
Therefore, the research group has developed a "drinking thermometer" that acquires energy from gastric acid power generation.The external dimensions of the prototype tablet sensor are about 9 mm in diameter and about 7 mm in thickness.Except for the electrode metal plate of the gastric acid battery, it is covered with resin, and a temperature sensor, microcomputer, custom integrated circuit, communication coil, multilayer ceramic capacitor, etc. are mounted inside the resin.When the sensor is swallowed and the gastric acid comes into contact with the gastric acid battery electrode, it generates electricity, and before the sensor passes through the stomach, the generated energy drives the booster circuit to charge the condenser with a high voltage.
Using this charging energy, the intestinal temperature is measured about once every 30 minutes and the data is sent to the receiver outside the body.For communication outside the body, a short-range magnetic induction method is used in the frequency band of about 1 MHz, which has extremely little absorption inside the body.It is assumed that the sensor will be discharged to the outside within 10 hours, and that it will be collected and disposed of in the sedimentation process of the sewage treatment plant.
As a result of taking the prototype sensor to an animal and verifying its operation, the operation of the entire system of power generation, temperature measurement, and communication was confirmed, and the concept was successfully demonstrated.In the future, it is aiming for application tests to humans while considering extending the communication distance and reducing the price (cost 100 yen or less).It is expected to lead to early detection of illness and improvement of health.
