title: Successful pacing using a batteryless sunlight-powered pacemaker.
abstract: OBJECTIVE
  Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker.
  
  
  RESULTS
  We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P < 0.001). Finally, a batteryless single-chamber pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed.
  
  
  CONCLUSIONS
  Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers.
authors.affiliation: Department of Cardiology, Inselspital, Bern University Hospital, 3010 Bern, Switzerland ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland andreas.haeberlin@insel.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Haeberlin
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Zurbuchen
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland.
authors.forename: Jakob
authors.initials: J
authors.lastname: Schaerer
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland.
authors.forename: Joerg
authors.initials: J
authors.lastname: Wagner
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Walpen
authors.affiliation: Department of Cardiovascular Surgery, Bern University Hospital, 3010 Bern, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Huber
authors.affiliation: Photovoltaics laboratory, Bern University of Applied Sciences, 3400 Burgdorf, Switzerland.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Haeberlin
authors.affiliation: Department of Cardiology, Inselspital, Bern University Hospital, 3010 Bern, Switzerland.
authors.forename: Juerg
authors.initials: J
authors.lastname: Fuhrer
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, 3010 Bern, Switzerland Department of Cardiology, Bürgerspital Solothurn, 4500 Solothurn, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Vogel
mesh_terms: D000818:Animals; D011211:Electric Power Supplies; D004867:Equipment Design; D005240:Feasibility Studies; D008422:Materials Testing; D010138:Pacemaker, Artificial; D013472:Sunlight; D013552:Swine
keywords: Batteryless pacemaker; Electrophysiology; Energy harvesting; Pacemaker; Pacing; Solar pacemaker