Assessment of the Safety Risk of Dermatoscope Magnets in Patients With Cardiovascular Implanted Electronic Devices

Importance Cardiovascular implanted electronic devices (CIEDs) are susceptible to electromagnetic interference. Dermatologists regularly use devices containing magnets, including dermatoscopes and their attachments, which could pose a hazard to patients with CIEDs. Objective To investigate the safety risk of magnets in dermatoscopes to patients with CIEDs. Design, Setting, and Participants This cross-sectional observational study was conducted between January 1, 2018, and March 31, 2018, in a controlled laboratory setting. Two experiments were performed. In the first experiment (performed in the Dermatology Service at Memorial Sloan Kettering Cancer Center, New York), dermatoscopes that contain magnets were obtained from 3 manufacturers. Using a magnometer, the magnetic field strength of the dermatoscopes was measured over the magnet; at the faceplate; and at a distance of 0.5 cm, 1 cm and 15 cm away from the faceplate. In the second experiment (performed in the University Heart Center Zurich, Zurich, Switzerland), ex vivo measurements were conducted to determine how the dermatoscopes affected old-generation and new generation CIEDs (pacemakers and implantable defibrillators). Main Outcomes and Measures Magnetic field strength as measured directly over the dermatoscope magnet; at the faceplate; and at distances of 0.5 cm, 1 cm, and 15 cm from the faceplate. Pacemaker and defibrillator operation when exposed to dermatoscopes. Results After conducting 24 measurements, the magnetic field (measured in gauss [G]) strength varied between 24.26 G and 163.04 G over the dermatoscope magnet, between 2.22 G and 9.98 G at the dermatoscope faceplate, between 0.82 G and 2.4 G at a distance of 0.5 cm, and between 0.5 G and 1.04 G at a distance of 1 cm; it was 0 for all devices at a 15 cm distance. The field strength at the faceplate was found to be generally below the CIED industry standard safety threshold. None of the dermatoscopes in the ex vivo experiment exerted any demonstrable disruptions or changes to the CIEDs. Conclusions and Relevance In real life, dermatoscope magnets likely present no measurable safety risk to patients with CIEDs. Using the polarized noncontact mode permits dermoscopy to be performed at least 0.5 cm from the skin surface, where the magnetic field strength was well below the 5-G safety threshold

A Glucose Fuel Cell for Implantable Brain–Machine Interfaces

We have developed an implantable fuel cell that generates power through glucose oxidation, producing steady-state power and up to peak power. The fuel cell is manufactured using a novel approach, employing semiconductor fabrication techniques, and is therefore well suited for manufacture together with integrated circuits on a single silicon wafer. Thus, it can help enable implantable microelectronic systems with long-lifetime power sources that harvest energy from their surrounds. The fuel reactions are mediated by robust, solid state catalysts. Glucose is oxidized at the nanostructured surface of an activated platinum anode. Oxygen is reduced to water at the surface of a self-assembled network of single-walled carbon nanotubes, embedded in a Nafion film that forms the cathode and is exposed to the biological environment. The catalytic electrodes are separated by a Nafion membrane. The availability of fuel cell reactants, oxygen and glucose, only as a mixture in the physiologic environment, has traditionally posed a design challenge: Net current production requires oxidation and reduction to occur separately and selectively at the anode and cathode, respectively, to prevent electrochemical short circuits. Our fuel cell is configured in a half-open geometry that shields the anode while exposing the cathode, resulting in an oxygen gradient that strongly favors oxygen reduction at the cathode. Glucose reaches the shielded anode by diffusing through the nanotube mesh, which does not catalyze glucose oxidation, and the Nafion layers, which are permeable to small neutral and cationic species. We demonstrate computationally that the natural recirculation of cerebrospinal fluid around the human brain theoretically permits glucose energy harvesting at a rate on the order of at least 1 mW with no adverse physiologic effects. Low-power brain–machine interfaces can thus potentially benefit from having their implanted units powered or recharged by glucose fuel cells