Energy-sparing systems for use in medicine: Past, present and future solutions

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Abstract
Summary. Implantable devices for medical use like permanent pacemakers, defibrillators and fluid pumps depend on energy provided by batteries. Unfortunately, the battery usually determines the duration of life of these devices, while technical problems occur infrequently. Replacement due to battery exhaustion requires surgical procedures and accounts for up to one-third of all pacemakers sold. Attempts to provide unlimited power support using radio transmission, nuclear energy, etc., did not gain clinical acceptance. We therefore evaluated the potential role of a microgenerator (designed for use in wrist watches) to recharge pacemaker batteries. We used the EPSON-SEIKO Caliber 5M22 that uses a ‘Gold-Cap’ for energy storage. The mass of the actuator is 1.6 g and an angle of >10° is needed to overcome friction. Output at a rotor frequency of 200 Hz is 1.8 mW. To measure the power provided, various experiments were made with the microgenerator taped to the chest of a normal person working in an office. A typical wearing experiment over a working day resulted in 0.9 to 6.1 μW. By taking a bridge rectifier into account, 12.2μW were delivered. The demands of a pacemaker are 34.3μW. Thus, this commercially available, yet not optimized microgenerator provides already approximately one-third of the power requirements of a pacemaker, making a ‘lifetime warranty’ for implanted devices a possibility for the future.