Development of a Bidirectional Data Communication System Using Ultra High Frequency Radio Wave for Implantable Artificial Hearts

摘要

In order to minimize infection risks for patients with artificial hearts, wireless data transmission methods with electromagnetic or optical transcutaneous data transmission have been developed. However, using these methods, it tends to become difficult to transmit data if the external data transceiver moves from its proper position because the communication distance is short. To resolve this problem, the purpose of this study is to develop a bidirectional data communication system using ultra high frequency radio wave for implantable artificial hearts, and confirm its performance. Due to its long communication distance, high-speed communication rate, low power consumption, high tolerance to electromagnetic disturbances, and secure wireless communication, we adopted Bluetooth radio wave technology for our system. The system consists of an internal unit and an external unit, each having a Bluetooth module (radio field intensity: 4 dBm, receiver sensitivity: -80 dBm). In addition, the internal unit has an 8-bit D/A converter and a micro controller with an 8-channel 10-bit A/D converter, while the external unit also has a RS-232C converter. We experimented with the internal unit implanted into pig meat (tissue thickness: 5 mm), carrying out a data transmission test and a control test in order to evaluate the performance of this system. As a result, data transfer speeds of about 20 kbps were achieved within the communication distance of 8 m. Moreover, the speed control of an artificial heart was achieved at a distance of 1 m. In conclusion, we confirmed that the system can wirelessly transmit data from the inside of a body to the outside while controlling an artificial heart, thereby preventing unstable data transmission due to accidental movements of the external data transceiver unit. It will contribute to effective medical treatment by continually monitoring the conditions of both the patient and the artificial heart and adequately controlling it.