Cryogenic remote sensing physiograph

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.

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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
There has long been a need for remotely monitoring basic human 
physiological data. The main problems in this type of biomonitoring is 
recognizing signals such as EKG, EEG, EMG, EOG and respiration at a point 
remote from the human subject being monitored and separating these various 
signals from background noise and other sources of interference. These 
super-low frequency (SLF) and extremely-low frequency (ELF) 
electromagnetic waves are generated and propagated by the human body in 
the frequency range of from about 0.3 Hz to about 40 Hz. 
The cryogenic remote sensing physiograph (CRESP) system of the present 
invention uses three basic elements for the investigation of 
electromagnetic waves in the 0.3 to 40 Hz range. These elements comprise 
an arrayed antenna of special design, an analog signal conditioner with 
fiber optic data links and low pass filtering, and a digital signal 
processor with 4-port memory. FIG. 1 is a block diagram of the entire 
CRESP system. FIG. 2 is a top sectioned view of the supercooled arrayed 
antenna with FIG. 3 comprising a partial section view of the arrayed 
antenna of FIG. 2. 
Referring initially to FIGS. 2 and 3, the arrayed antenna 10 of the 
invention consists in its primary structure of a three element array of 
super-conducting niobium plates 12 for the detection of electromagnetic 
waves in the 0.3 to 40 Hz range. The niobium plates 12 are preferrably 
rectangular in shape, measuring 8".times.10" with a thickness of 
approximately 30 mils, and are arrayed within an equilateral triangular 
outer enclosure 14. The antenna plates 12, each located at a corner within 
the outer triangular enclosure 14, are also individually enclosed in an 
inner antenna housing 16 defining space 18 containing recirculating liquid 
helium. The outer enclosure 14 has parallel top and bottom walls 14a and 
14b, respectively, and annular wall 14c formed of carbon-fiber composite 
material or polycarbonate and the inner housings 16 have walls formed of 
the same material. The internal surfaces 16a of the antenna housings 16 
are aluminized and space 20, surrounding the antenna housings and defined 
by outer enclosure 14, is maintained under vacuum. The vacuum may be drawn 
on space 20 within enclosure 14 via outlet pipe 14a. Thus, each antenna 
plate 12 is (in effect) contained in a Dewar flask type arrangement, i.e., 
a double-wall container that has an evacuated space (space 20) between its 
outer wall (enclosure 14) and inner wall (housing 16) with its innermost 
surfaces 16a bearing a reflective coating to inhibit heat transfer between 
the liquid helium in space 18 and the ambient atmosphere surrounding the 
arrayed antenna enclosure 14. 
The three antenna housings 16 are interconnected by pipe sections 22 of 
carbon-fiber composite or polycarbonate material having internally 
aluminized surfaces. These pipe sections assist in supporting and 
positioning the antenna plate housings 16 within the triangular enclosure 
14 and provide means for circulating liquid helium throughout the antenna 
system. Liquid helium may be introduced to such system by inlet pipe 24 
and withdrawn from the system by outlet pipe 26. 
To the rear of each antenna plate housing 16 is a separate Dewar 
arrangement 28 consisting of an outer spherical housing 30 and a spaced 
inner spherical encasement 32 within which is contained the individual 
array element analog circuitry package 34 including a field effect 
transistor (FET), preamplifier, filter and D. C. power supply. Each array 
element package 34 incorporates its own low-noise, optically isolated 
analog source-following circuitry and an output amplifier. The space 36 
between spherical housing 30 and spherical encasement 32 of each Dewar 
arrangement 28 is interconnected to the space 18 of its associated antenna 
housing 16 by a pipe section 40 so that liquid helium is circulated within 
space 36. 
From the foregoing description of the arrayed antenna 10 of the invention, 
it will be noted that each antenna plate 12 and each associated circuitry 
package 34 is encased in a supercooled environment. Circulation of liquid 
helium throughout the antenna structure may be accomplished by a 
closed-cycle, unvented, nonconsumable, recirculating system (not shown in 
FIG. 2) such as the "Heliplex" System produced by Air Products and 
Chemicals, Inc. Through appropriate control of the helium recirculating 
system the temperature of the niobium antenna plates 12 may be maintained 
at a desired operating temperature of approximately 3.7.degree. Kelvin. 
Each of the Dewar arrangements 28 (encompasing the circuitry packages 34) 
are thermally regulated to a temperature of about 77.degree. K. through 
the use of a power transistor and thermostat powered by an internal D. C. 
power supply to avoid any coupling with stray A. C. power fields. The 
antenna leads 42 and output leads 44 from each of the Dewar-encased 
circuitry packages 34 are composed of niobium-tin alloy to further reduce 
system noise. The leads 44 exit the outer enclosure 14 at a central point 
46 and connect to the analog signal conditioner of the CRESP system of the 
invention through cable 48. 
Referring now to FIG. 1, the previously described supercooled arrayed 
antenna is represented by box 10 and is shown in the proximity of a human 
subject represented by box S. The antenna, in accordance with the 
invention may be placed at a distance of up to twelve feet from the 
subject with no contact with, or connection made to, the subject. The 
antenna cable 48, comprising the antenna array output leads 44, is coupled 
to the analog signal conditioner section 50 of the CRESP system. The 
optically isolated (low-noise) first stage 52 of signal conditioner 50 
reduces the random 1/f noise of the antenna transistors and improves the 
signal-to-noise ratio of the system. The antenna signals are next passed 
to the fiber optic data link stage 54 of the conditioner 50 and thence 
into a low-pass filter stage 56. The low-pass filters are required to 
eliminate noise and frequencies over 40 Hz. It is especially important 
that these filters are tuned to null at 60 Hz. Further, the filters must 
be designed for sufficient stability and high Q to assure that successive 
stages will not be saturated by a 60 Hz power field. The 60 Hz power 
fields are typically generated by A. C. power lines within walls, overhead 
lighting systems, and various electro-mechanical apparatus in the 
immediate proximity of the CRESP system as part of the normal environment 
within which the system will be operated. 
The output 58 of the low-pass filter stage 56 is connected to a very fast 
(nanosecond), 16-bit analog-to-digital converter 60 which converts the 
analog information to digital information so that it can be stored in the 
4-port memory section 62 of a minicomputer 64. The 4-port memory section 
62 has serial, in time sequencing with overlapping memory windows. This 
4-port memory flows into four hard-board Fast Fourier Transform- (FFTs A 
to D) dedicated outboard microprocessors 66a-66d and four outboard 
dedicated autocorrelator microprocessors (correlators A to D) 68a-68d. The 
FFT and autocorrelator microprocessors are coupled to the minicomputer 64 
(32-bit) with an array processor and incorporating signal discriminating 
software such as the previously mentioned Micro Vax II software by Digital 
Equipment Corporation. The minicomputer 64 uses the FFT and 
autocorrelation analysis to examine the time dependence of amplitude and 
frequency modulation for frequencies in the range of 0.3 Hz to 40 Hz. 
Explanations of how this analysis may be accomplished are contained in the 
following references: 
(1) Cochran, W. T., "What is the Fast Fourier Transform?", IEEE 
Transactions on Audio and Electroacoustics, Vol AU-15, No. 2, June 1967 
(2) Brigham, O. E., The Fast Fourier Transform, Prentice-Hall, Englewood 
Cliffs, N.J., 1974 
(3) Raeder, W. A., The Fast Fourier Transform: A Bibliography, TRW Systems, 
Redondo Beach, Calif. 1969 
(4) Luk, A. L., Parallel Processing of the Fast Fourier Transform Via 
Memory Organization, M.S. Thesis in Computer Science, UCLA, 1976 
The FFTs 66a-66d and autocorrelators 68a-68d separate the SLF/ELF fields 
emitted by the human subject S into component waveforms as they are 
related to specific internal organ functioning such as EKG, EEG, EMG, EOG 
and respiration. After the FFT, autocorrelation and signal discrimination 
functions are completed by the minicomputer 64, the signal is sent 
directly to a multichannel waveform display unit 70 (color video display 
terminal) or physioscope, as well as being sent through a series of 
multichannel digital-to-analog (very fast) converters 72 that pass their 
output to a chart recorder or electrostatic printer 74 which records the 
various component waveforms on a chart. 
FIG. 4 shows a patient or subject S being monitored by the arrayed antanna 
structure 10 of the invention. The antenna is attached to a wall W of an 
examination room by support arms A. The antenna output signals are passed 
to the analog signal conditioner section of the CRESP system through cable 
48. The triangular antenna structure is positioned parallel to the subject 
S and aligned so that one of the antenna plate elements is directly over 
the head and chest area of the subject. The remaining two array plate 
elements are positioned over the lower torso area of the subject. The 
antenna 10 may be attached to the structure of the bed B or a wheeled cart 
containing the CRESP system. 
The following comprises a discussion of the factors determining the 
selection and design of an appropriate antenna for the remote monitoring 
of 0.3 to 40 Hz electromagnetic waves. Wavelengths of frequencies in the 
0.3 Hz to 40 Hz range are extremely long, 1.times.10.sup.9 meters to 
7.5.times.10.sup.6 meters, respectively, and the distance between any 
system involving a transmitter (a human body) and a receiver (the system 
of the present invention) will be considerably less than the wavelengths 
of the signals being measured. Thus, the super-low frequency (SLF) and 
extremely-low frequency (ELF) signals and their concomitant long 
wavelengths demand novel approaches when the antenna is placed at a 
distance anywhere from two to twelve feet away from the transmitter, i.e., 
the human subject being monitored. 
Due to the superlong wavelengths, the classical approach to antenna theory 
does not hold. Under such circumstances, the antenna problem is reduced to 
a matter of electrostatics. Examination of the various conditions shows 
that the antenna problem may be resolved into three basic cases. In case 1 
the transmitter is distant from a large ground plane and the receiver is 
near the large ground plane. In the second case, the transmitter and 
receiver are in free space. In the third case, both the transmitter and 
receiver are located near one another and both are in the presence of a 
large ground plane. 
For the first case above, the theoretically best antenna is the largest 
possible section of the ground plane which is insulated from the rest of 
the ground plane. This because the electric field is perpendicular to the 
plane. The sensitivity is in proportion to the size of the plane antenna. 
For the second case above, there must be an electric dipole formed for 
reception. In this case, the optimum antenna is the largest possible 
parallel plane capacitor, with the best sensitivity in the vector which is 
perpendicular to the plane of the antenna. For the third case above, the 
receiver should be connected to a common ground plane. The antenna is a 
large conductive sheet oriented perpendicular to the subject being 
monitored. 
The foregoing antenna problems and needs for accomplishing the remote 
monitoring of basic physiological data are solved by the unique arrayed 
antenna structure of the present invention integrated into the CRESP 
system as described hereinbefore. 
The output of the antenna array analog signal conditioners of the CRESP 
system consists of a complex waveform emanated from the human body. This 
complex waveform is composed of various wavelengths and amplitudes which 
correspond to internal physiological processes and a typical waveform, as 
actually processed by the apparatus and methodology of the invention, is 
shown in FIG. 5. The computer FFT/autocorrelation analysis separates this 
complex waveform into its various frequency/amplitude components as they 
are related to the specific internal organ functioning. FIGS. 6, 7, 8 and 
9 show typical EKG, EEG and respiration waveforms, respectively, as 
actually generated by the apparatus and methodology of the invention, 
after FFT/autocorrelation analysis and D/A convesion. EMG and EOG 
waveforms have not been shown. 
While a preferred embodiment of the present invention has been illustrated 
and described, modifications and variations thereof will be apparent to 
those skilled in the art given the teachings herein, and it is intended 
that all such modifications and variations be encompased within the scope 
of the appended claims.