Miniaturized low-field thoracic magnetic stimulation device for assessing effects on peripheral oxygen saturation levels in healthy rats

<i>Objective.</i>This study aimed to develop a miniaturized low-field thoracic magnetic stimulation (LF-ThMS) device to evaluate its effects on peripheral oxygen saturation (SpO₂) in healthy rats. This investigation was motivated by prior findings that LF-ThMS at 10.5 to 13.1 mT increased SpO₂in patients with COVID-19. However, its effect on healthy subjects remains unknown. To address this gap before extending research to healthy humans, we first examined its effects in healthy animal models.<i>Approach.</i>A miniature low-field thoracic magnetic stimulation (LF-ThMS) device, also referred to as a pulsed electromagnetic field (PEMF) system, was developed using two 30-turn coils made of 13-gauge magnet wire, encased in nylon sheaths. The coils were powered by a 30 V, 13 A DC source to generate magnetic pulses up to 13.1 mT. A custom control circuit, featuring an ATmega328P microcontroller, relays, and MOSFETs, regulated the pulse frequency and included a safety system to maintain coil temperatures below 38 °C. The device also featured a user interface for customizable and reproducible operation. Peripheral oxygen saturation (SpO₂) was monitored using a NONIN 750 pulse oximeter.<i>Main results.</i>The LF-ThMS device successfully generated magnetic flux densities of 10.5, 11.6, and 13.1 mT. However, when we compared SpO₂levels between the control condition (before LF-ThMS) and the SpO₂levels after the LF-ThMS at these intensities, we did not find a statistically significant difference. S<i>ignificance.</i>These results suggest that LF-ThMS may not affect SpO₂in healthy individuals, and the improvements observed in COVID-19 patients could be due to disease-specific mechanisms or other unknown factors, rather than a general physiological effect of LF-ThMS.