Patent No. 4940058 Cryogenic remote sensing physiograph

 

Patent No. 4940058  Cryogenic remote sensing physiograph (Taff, et al., Jul 10, 1990)

Abstract

Apparatus and method for remotely detecting super-low frequency (SLF) and extremely-low frequency (ELF) signals eminating from human subjects. The SLF/ELF signals are composed of various wavelengths and amplitudes which correspond to the subjects internal physiological processes. The apparatus includes: a supercooled multi-plate arrayed antenna for detecting the SLF/ELF signals; an analog signal conditioner unit adapted to filter out signals having a frequency of greater than 40 Hertz; and a digital signal processor unit adapted to perform Fast Fourier Transform and autocorrelation signal analyses for separating signal wavelengths and amplitudes which correspond to the internal physiological processes and represent EKG, EEG, EMG, EOG and respiration measurements.

Notes:

BACKGROUND OF THE INVENTION

Many physiological processes are characterized by the generation and propagation of multiple, dynamic and often transient electrical phenomena from the respective tissues and organs where they originate. The purpose of recording physiological signals is to obtain a record which is an exact facsimile of the events under investigation. However, it is seldom feasible to attach pickup elements directly to the tissues or organs being investigated, and some method of sensing the electrical phenomena from the surface of the body is usually employed. Such methods introduce measurement errors that result in a distorted picture of the processes being recorded. In spite of this limitation, these techniques have proven to be highly useful for the medical profession.

A wide variety of pickup elements of various sophistication have been developed and are presently available for recording many important phenomena associated with various physiological function from different anatomical sites. The important requirements for sensing electrodes and transducers presently employed in electrophysiological monitoring and recording are: (a) attachment to the body must result in a minimum of discomfort and movement restriction; (b) once applied, they should maintain their operation status without deterioration for extended periods of time; (c) avoid the necessity for reapplication and/or relocation; and (d) they must allow for a far greater degree of subject movement than usually prevails in clinical investigations.

Although a great deal of effort has already been spent in reducing the weight and size of electrodes and transducers, and in minimizing the adverse effects that occur over prolonged time periods, the present state of the art is far from ideal.

The methods employed for applying even simple bioelectric pickup electrodes in many instances is quite traumatic, as they require abrasion and debridement of the superficial keratinized skin layers. Such procedures frequently cause discomfort, and many contribute to the cause of skin reactions when electrodes are left applied to the same locations for many hours or days. The following scientific studies published in scientific and medical Journals are indicative of previous efforts in remotely recording electromagnetic fields that correspond to internal physiological processes of biological organisms without the use of any intermediary materials or electrodes attached to the skin:

(1) Burr, H. S., and Northrop, F., "The Electrodynamic Theory of Life", Quarterly Review of Biol., 1935, 10:322

(2) Burr, H. S., and Northrop, F., "Evidence For The Existence Of An Electrodynamic Field In Living Organisms", National Academy of Sciences, 1939, 25:284

(3) Burr, H. S., and Maure, A., "Electrostatic Fields of Sciatic Nerve In The Frog", Yale J. of Bio. Med., 1949, 21:455

(4) Seipell, H., and Morrow, R., "The Magnetic Field Accompanying Neuronal Activity Of The Nervous System", J. Wash. Acad. Sci., 1960, 50:1

(5) Cohen, D., "Magnetoencephalography: Evidence Of Magnetic Fields Produced By Alpha-Rhythm Currents", Science, 1968, 161:784

(6) Cohen, D., "Magnetoencephalography: Detection Of Brain's Electrical Activity With A Superconducting Magnetometer", Science, 1972, 175:664

(7) Cohen, D., "Magnetic Fields Of The Human Body", Physics Today, Aug. 1975, pp. 34-43

(8) Gulyaev, P. I., Zabotin, V. L. & Shippenbakh, N.Y., "The Electroauragram Of The Frog's Nerve, Muscle, Heart And Of The Human Heart And Musculature", Doklady Biological Science, 1968, 180, pp. 359-361

(9) Gulyaev, P. I., "The Electroauragram: The Electric Field Of Organisms As A New Biological Connection", Proceedings Of Symposium On Physics And Biology, Moscow, 1967, p. 19

(10) Goodman, D. A. and Weinberger, N. M., "Remote Sensing Of Behavior In Aquatic Amphibia Especially In Necturus Maculosus, The Mud Puppy", Comm. Behavioral Biology, 1971, 6, pp. 67-70

(11) Goodman, D. A. and Weinberger, N. M., "Submerged Electrodes In An Aquarium: Validation Of A Technique For Remote Sensing Of Behavior", Behav. Res. Meth. & Instru., 1971 3:6, pp. 281-286

Other devices have eliminated the necessity of topically connecting electromagnetic sensors to a person's skin. Some of these devices are described in U. S. Pat. Nos. 3,980,076 (Wikswo et al), 4,079,730 (Wikswo et al) and 4,444,199 (Shafer). However, these devices are not totally remote in that they will not operate through the ambient atmosphere from up to 12 feet away. Similarly, there have been problems in measuring the EKG, EEG, EMG, EOG and respiration in the super-low frequency (SLF) and extremely-low frequency (ELF) range of 0.3 to 40 Hertz. Thus, there exists a need for the development of physiological monitoring methods and equipment that do not require direct contact with the subject's integument (skin layer), and thus relieve the subjects from annoyance and encumbrance of bodily attachments.

SUMMARY OF THE INVENTION

The invention comprises a method and apparatus (or system) for the investigation of electromagnetic (EM) waves in the 0.3 to 40 Hertz realm. The SLF/ELF frequency range is generally considered to be from D. C. to approximately 100 Hz. As used herein, superlow frequency (SLF) and extremely-low Frequency (ELF) is a frequency from 0.3 to 40 Hz that corresponds to internal physiological processes. The elements necessary for this type of system are: an antenna, an analog signal conditioner, fiber-optic data links, and a digital signal processor. In the preferred embodiment of the invention the antenna consists of a three element array of supercooled super-conducting niobium plates for the detection of electromagnetic waves in the 0.3 to 40 Hz range with amplitudes in the nanovolt to millivolt range. The three element antenna array is for spatial signal referencing. Each antenna element has its own integral field effective transistor (FET), pre-amplifier and filter which are enclosed in a separate, thermally regulated (via power transistor and thermostat) Dewar flask arrangements at 77.degree. C. Kelvin as opposed to the niobium antenna plate elements which are cooled to 3.7.degree. K. The arrayed antenna is capable of detecting SLF/ELF signals at distances of up to 12 feet. The arrayed antenna output is coupled to the input of low noise, optically isolated analog signal conditioner circuitry with self-contained power source incorporating a follower circuit and output amplifier. The analog signal circuitry has optically isolated (low-noise) first stage which reduces the random 1/f noise of the transistor which in turn improves the signal-to-noise ratio.

The next stage of the analog signal conditioner is an analog fiber-optic data link flowing into a low-pass 40 Hz filter which serves as an output buffer. The output of the signal conditioner is coupled to the input of the digital signal processor system. The input of the digital signal processor is a very fast (nanosecond) 16-bit analog-to-digital converter which allows for the storage of waveforms in the computer memory. The computer (such as a Micro Vax II by Digital Equipment Corporation) then uses a 4-port memory having serial in-time sequencing with overlapping memory windows flowing into four hard-board Fast Fourier Transform (FFT) microprocessors and four autocorrelators which are outboard, dedicated microprocessors. These FFT s and autocorrelators are coupled to a 32-bit mini computer with an array processor incorporating signal discriminating software (Micro Vax II software by Digital Equipment Corporation). The computer uses the FFT and autocorrelation analysis to examine the time dependence of amplitude and frequency modulation in the frequency range of 0.3 to 40 Hz. The FFTs and autocorrelators separate the SLF/ELF fields emitted by the human subject into component waveforms as they are related to specific internal organ functioning such as Electrocardiogram (EKG), Electroencephalogram (EEG), Electromyogram (EMG), Electrooculogram (EOG) and respiration. After the FFT, autocorrelation and signal discrimination functions are completed, the signal is sent directly to a multi-channel waveform display (color video display terminal) or physioscope, as well as being sent through a series of multi-channel digital-to-analog converters (very fast) that lead to a chart recorder or electrostatic printer which records the various component waveforms on a chart.

It is an object of the present invention to provide an improved method and apparatus or system for monitoring physiological changes in a human subject without attaching electrodes and/or sensors or other devices to the subject's body.

Another object of the present invention is to permit the unshielded remote monitoring of a human subject at a distance of up to 12 feet.

Still another object of the invention is to provide a system that is substantially insensitive to other electrical equipment operating in the same area and to provide a system with a high signal-to-noise ratio.

It is a further object of the invention to provide a system that has the ability to discriminate between readings of EKG, EEG, EMG, EOG and respiration.