Inductively Coupled Electrical Stimulation - Part 3: PEMF Systems for use in Basic Research with Laboratory Animals and In Vitro

Abstract

A system is described whereby calibrated pulsed electro-magnetic fields, generally known as PEMF (ICES®-PEMF) can be tested on laboratory rodents (rats and mice) by application of the electro-magnetic pulses through the exterior of the bottom of the cage. These systems may also be reconfigured for various other experimental conditions, and are based on the elucidation of well-defined electro-magnetic parameters, determined by earlier experimental work to result in consistent, reliable, beneficial biological effects while requiring very low levels of RMS electro-magnetic power, and at low frequencies (< 1 KHz primary). The systems described in this report, or their derivatives, are currently in use and are planned for use in numerous basic experiments, and have been used in private testing laboratories as well as academic research. These systems may, for example, involve an array of 4 x 8 (32 total) 40 mm diameter coils powered by 8 synchronized PEMF pulse generators, or a similar system modified for use with cell and tissue samples in a 35 mm diameter Petri dish or other small sample chamber, which may also be used in a cell culture incubator or with a microscope. For testing with laboratory animals, the coil array is built into a magnetically-transparent plate which rests below the bottom of standard plastic caging systems. The pulse generators produce tuned trapezoidal bipolar pulses with 100 micro-second rise times, programmable pulse patterns, and magnetic flux (Gauss) slew rates up to 1600 kG/s. These systems can be used to test the effects of short- or long-term PEMF exposure on untethered, individually or group-housed mice and rats in standard micro-isolation cages. The coil configuration is modified to suit the needs of small sample chambers for cell and tissue culture or microscopic analysis, and can be used for imaging cell growth dynamics, calcium signaling, etc. The system operates on ultra-low power (5.0 Volt USB charging port at 2.1 Amps rated maximum), and has been uniformly approved by institutional animal care and use committees each time its use was proposed, primarily because it has the features that it requires no restriction to the movement of animals within the cage, does not interfere with grooming or feeding or social behavior, is entirely non-invasive, and requires no changes to the standard, approved caging systems in use at the time of their review and approval. The ICES®-PEMF driver circuit remains essentially unchanged, but the coil geometry and configuration can be readily adapted to different coil array configurations, for different sized cages, different cage mounting systems, and for in vitro PEMF testing of cultured cells both in an cell culture incubator, as well as in the form of a solenoid fixture for optical microscopic examination of living cells and tissue samples.