A pilot study in energy harvesting to surrogate the power source for pacemakers

Abstract

The natural pacemaker of the heart is located in a small region named the sinoatrial node. The electrical stimulus generated in the SA (Sinoatrial) node passes in sequence through different anatomical locations in the cardiac conduction system and causes the heart to beat. As a result of heart disease, the normal electrical conduction pathway can get interrupted subsequently leading to the heart beating in a pathological rhythm known as an arrythmia. There is no arguing that implantable cardiac pacemakers have drastically improved the quality of life of many patients suffering from arrythmias and are recognized as the gold standard when it comes to treating arrythmias. The form factor and conditions that are treated have come a long way from the very first implantable pacemaker manufactured in 1958. That being said, the long term operation of such devices remains an obstacle due to their limited battery life which is usually limited to 7-10 years for modern pacemakers, after which the patient must undergo surgery to remove the old pacemaker box and replace it with a new one. One possible way of extending the life of pacemakers is by harvesting power from the surrounding kinetic energy within the body via the use of energy harvesting devices. One such energy harvesting device of interest for biological applications are the Triboelectric Nanogenerators, commonly abbreviated to TENG, which use the phenomena of triboelectrification between two contacting surface to generate power. In this project, various TENG devices incorporating the contact surfaces of PDMS (Polydimethylsiloxane) and silver nanoparticles were successfully fabricated using different manufacturing processes. The performance of the devices were subsequently tested under uncontrolled and controlled testing methods. Under controlled testing, the best performing TENG device had a maximum power output of 6.60µW using a bradycardic testing frequency and 17.90µW using a tachycardic testing frequency. This was achieved by using the combination of 12µg/cm2 silver nanoparticle coating and using the PDMS film that was bonded to the PDMS substrate and that had no surface modification. Comparison of the RMS power obtained from this device with a commercial pacemaker and ICD (Implantable Cardiac Defibrillators) device on the market shows that a small percentage of the power needed to power such devices was extracted from the TENG devices. Taking a state of the art pacemaker indicated for single chamber pacing of bradycardia , the extracted RMS power of the TENG accounted for 0.35% and 0.30% of pacemaker’s power requirements in 100% inhibition mode, where the pacemaker is using its energy to solely sense, and 100% pacing mode, where the pacemaker is using all its energy to solely pace, respectively. Better results were obtained for the leadless pacemakers where the extracted RMS power of the TENG accounted for 8.14% and 3.94% of the device’s power requirements in 100 % pacing mode and 100 % inhibition mode respectively. Lastly, with regard to the ICD, the extracted RMS power of the TENG accounted for 1.221% and 1.079% of the ICD power requirements on 100% inhibition and 100% pacing mode respectively.