A small solar panel implanted under the skin could be used to keep battery-operated cardiac biosensors up to power without the need for repeated surgical intervention to replace run down batteries, according to research published in the International Journal of Biomedical Engineering and Technology.
Electrical engineers Munna Khan and Ajai Kumar Singh of Jamia Millia Islamia (Central University), in New Delhi are working alongside Syed Shakir Iqbal of Freescale Semiconductors India in Uttar Pradesh, India, to develop a sustainable power supply for devices commonly referred to as heart pacemakers. The team has tested a photovoltaic panel that could be implanted under the skin and would charge a pacemaker battery converting absorbed near-infrared NIR light into electricity. The team used SPICE – Simulation Program for Integrated Circuits Emphasis – to model the behavior of an implantable photovoltaic array and point out that human skin at 2 millimeters thickness has sufficient transparency, 10-20 percent, to NIR. The array could provide 10 to 25 milliwatts of power at a current of between 6 and 14 milliamps.
Cardiac biosensors are commonly used to maintain the rhythmic action of the heart with precise and continuous monitoring in modern healthcare technology, the team reports. Implantable cardiac biosensors are critically required for survival of patients suffering from heart problems including bradycardia, tachycardia and fibrillation. Modern pacemakers and related devices are almost fully autonomous and wireless sensor technology allows the patient’s doctor to monitor and control the device’s output remotely and entirely non-invasively and without restricting the day to day life of the patient. “The sensor must be able to function for a prolonged period and therefore power consumption and management becomes a key design requirement for biomedical implants,” the team says.
Other researchers have investigated the potential of NIR energy harvesting for medical implants. However, the Indian team has developed what they refer to as “a more realistic implementation” of Maximum Power Point Tracking (MPPT) for an implanted photovoltaic array. Their approach should allow them to maximize the efficiency of power conversion for the first time. Their circuit design produces sufficient output voltage to charge the battery in a cardiac pacemaker at currents corresponding to different NIR intensities and so extends the replacement life of the device.
Khan, M., Singh, A.K. and Iqbal, S.S. (2015) ‘SPICE simulation of implantable solar power supply for sustainable operation of cardiac biosensors’, Int. J. Biomedical Engineering and Technology, Vol. 18, No. 2, pp.168–185.
Please contact the corresponding author, Ajai Kumar Singh, by email on firstname.lastname@example.org for further information about the research.
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