Whole body non-contact electrical stimulation device with variable parameters

This application claims benefit of U.S. Provisional Application 62/444,940, filed Jan. 11, 2017. The subject matter if that application is hereby included in its entirety.

The present invention relates to an electromagnetic device for non-contact injection of strong modulated electric fields into a whole human body at the frequency band 100-500 kHz.

The conventional MRI (Magnetic Resonance Imaging) RF (Radio Frequency) coil or a birdcage resonator known from MRI instrumentation cannot be used in the frequency band 100-500 kHz since its quality factor Q, the “gain” of the resonator, becomes very low (less than one). As a result, the induced electric field in a body will be low too. To achieve high levels of the stimulation electric field, a birdcage coil resonator operating at a much lower carrier frequency of around 100-500 kHz is required. The carrier may then amplitude-modulated by any required base frequency in the range of 0-1000 Hz or by constructing pulsed excitation with a center frequency not to exceed 1000 Hz.

Accordingly, a resonator with a high field, up to 1-2 volts per centimeter, that operates at much lower than frequencies is required. The birdcage resonator of the present invention uses a very large number of rungs in excess of 100 while the conventional MRI resonator uses 8-16 rungs. It also uses inductively coupled feeds. These two factors allow achievement of a very high quality factor of 300 and high-fields of 1-2 volts per centimeter. Such a device may be used to modulate the field level with any signal including electroencephalographic signals from the brain to establish closed-loop feedback for the entire peripheral and/or nervous system. Other potential applications include treatment of chronic pain, oncological and psychiatric applications.

The present invention provides a resonant non-contact device, wherein the device creates strong variable electric fields in the human body in the frequency band 100-500 kHz. The device of the present invention comprises a modified birdcage coil or birdcage resonator. The generally cylindrical birdcage coil is further comprised of a pair of end rings, a plurality of generally parallel rungs or column elements bridging the end rings, a plurality of matching capacitors, and two inductively coupled loop feeds connected to a source with a 90 degrees phase shift.

In a preferred embodiment, the end rings are disposed in parallel planes along the coil axis and the parallel rungs interconnect the end rings. The end rings may be detachable to the parallel rungs. The plurality of parallel rungs are spaced generally equally about the end rings. In a preferred embodiment, the parallel rungs are comprised of a conductive material, preferably copper, and preferably thin-walled copper tubing.

In a further embodiment, each parallel rung is comprised of two rung portions with a capacitor located at the attachment point of the two rung portions. The capacitors are located distal to the end rings and, preferably, equidistant to each end ring. The capacitors are, preferably matching and in the nanofarad range used to tune the resonator to the desired frequency.

In a preferred embodiment, two inductively coupled loop feeds are disposed outside the parallel rungs proximally to the coil center. Each loop feed is shifted 90 degrees about the coil axis.

In a further embodiment, the birdcage coil of the present invention is driven through two inductively coupled feeds in quadrature by an amplifier, preferably a 3 kilowatt power amplifier.

In a further embodiment, the power amplifier includes amplitude modulation in the frequency band 0-1000 Hz.

FIG. 1 a is a schematic representation of a birdcage resonator of the present invention.

FIG. 1 b is a schematic representation of a birdcage coil of the present invention.

FIG. 1 a shows a birdcage resonator 1 of the present invention. The resonator comprises end rings 5 , capacitors 4 , parallel rungs 3 , and inductive loop feeds 2 . The end rings 5 are disposed along parallel planes and are interconnected by the parallel rungs 3 . Each parallel rung 3 is comprised of at least two leg portions 6 . Capacitors 4 connect the rung portions 6 to form a parallel rung 3 . Inductively coupled loop feeds 2 are placed parallel to rungs 3 .

FIG. 1 b shows the birdcage resonator 1 supported by plastic frame 7 . FIG. 1 b further shows that each parallel rung 3 is comprised of at least two leg portions 6 .