Through-Wall Sensing, bioradiolocation

Through-Wall Imaging device PicoR-Bio

Most of the products of UWB technology developed and produced in JSC "KBOR" are for the bioradiolocation application. At present time in the Russian and foreign markets not so broad range of products of this field can be found, and we intend to occupy a remarkable niche on this promising market at the expense of the many unique features of our products.

Until recently during radar sensing in low-absorption and transparent environments by traditional radio locators, primarily inanimate matters (targets) were the objects of investigation just because it was the application field of using radar devices. Among these fields of traditional radars application are detection and navigation sighting:

• aerodynamic targets (such as aircraft, cruise missiles, etc.);

• ballistic and space objects (warheads, satellites);

• ground objects and surface crafts (ground and fighting vehicles, ships).

Another field of radiolocation application, rapidly developing in last decades, is subsurface investigations (georadiolocation), which gives the opportunity to survey in details the structure of the ground and constructions, other type of condensed matters with high absorption and dispersion of electromagnetic waves. Subsurface radiolocation the most widely may be used for the following purposes:

• sensing of soils to identify their deep structure and inhomogeneities (of ground water levels, various kinds of natural inclusions, the location and status of the technical constructions and communications);

• survey of areas to detect explosive devices, for example landmines;

• investigation of building constructions to determine their internal structure, such as reinforcement steel, construction defects;

• non-destructive testing of industrial products.

At present time there are a great number series-produced radars designed for solving the above mentioned tasks.

Decreasing cost of computing resources required for signal processing, as well as the miniaturization of microwave devices stimulate the development of interest in the radar usage, when reflecting object is either the entire body of a person or some part of him as well as innards. Detection of people behind of the opaque obstacles (building walls, foliage etc.) is relevant to both military and civilian purposes.

Modern methods allow detecting immovable, but alive people due to their innards fluctuations. This effect is used to locate survivors under the rubble of building constructions resulted from natural or technogenic disasters. The same can be used for medical purposes, when remote control monitoring a patient is required.

Reflected signal modulation caused by movements of the human body surface and his internal organs - cardiac beats, periodic fluctuations of vessels, lungs, other internal organs as well as articulation (simultaneous operation of pronouncing organs: vocal ligaments, tongue, lips, veil of palate). It is possible to determine four groups of biomechanical movements, which are differ both by frequency band and amplitude:

•  heartbeat (frequency range is 0,8..2,5 GHz, amplitude of breast fluctuation is 0,1 mm);

•  human breast fluctuation when breathing  (frequency range is 0,2..0,5 GHz, amplitude of breast fluctuation depending from breath type  is 0,5..1,5 cm);

•  human vocal organs movements (primary tone of vocal ligaments frequency is about 100 GHz);

•  other human organs movements (arms, legs etc.).

Certain rates of these frequencies and displacement amplitudes are determined by physical condition of the testee and his activity. The most complicated seem to be processes of articulation due to the fact that several human organs (and each of them with its own characteristics) all at once participate in that process. Investigation of articulation processes can be used for remote and automatic speech recognition without any acoustic devices applied, even in cases, when the testee is behind optically opaque obstacles, building walls, for example.

A method for detection and diagnostic monitoring of humans by means of radar, even behind optically opaque obstacles, based on the reflected signal modulation caused by movements of the body surface and internal organs will be called Bioradiolocation.

Effecting selection of penetrating radar signal from signals reflected from immovable objects (targets) it is possible to reach high sensitivity in targets discovery, boundaries of whose fluctuate. According to data in technical publications radar sensitivity in gigahertz frequency band, when sounding target is moving, can reach 10^-9 meters. The simplest way for detection of human subjects is to use low range radars working with continuous wave signals in 1… 10 GHz frequency band.

Below you will find a list of most prospective fields of bioradiolocation application:

•  detection of human subjects under the rubble caused by earthquake, technogenic disaster or avalanching, when early identification of location of living persons is very important;

•  detection and tracking of human subjects behind of the opaque obstacles or under the conditions of low visibility when antiterrorist operations are performed or when fighting in the urban area;

•  remote detection of wounded persons during battling by receiving their breathing signals to reduce the risk of medical personnel effecting evacuation under fire of the enemy;

•  remote detection of the person with fire or cutting weapon hidden under the clothes;

•  monitoring of protected areas from invasion of unauthorized persons;

•  search of transport containers with a view of identification of the persons illegally crossing the border;

•  remote identification of human emotional state to identify potentially dangerous persons, for example during preboarding security screening at airports;

•  development of remote polygraph detector allowing imperceptibly for the person to measure parameters of his cardiorespiratory system and on their basis to estimate his psychoemotional condition;

•   control of a condition of the operator of complex machine systems;

•   remote registration of voice signals of human subjects behind of the obstacles not using customary acoustic microphones;

•  monitoring of breathing and heartbeat signals of a patient in those cases when contact sensors usage either impossible or unfeasible;

•  monitoring of the innards condition as well as their diagnosis;

•  remote observation of a fetus across pregnancy (instead of monitors used ultrasonic along with contact sensors);

•  blood vessels elasticity determination by measuring of pulse velocity of blood pressure while heart beat, that will help to determine predilection of the patients to cardiovascular diseases.

The above listed directions are only potential fields of application bioradiolocation; further studies will be required to determine their practical realizability.

Already now we can say that the most promising area of bioradiolocation in medicine is Somnology.

Investigation of Obstructive Sleep Apnoea is the most studied section of sleep medicine.  Plenty of investigations in the field of Somnology related to Obstructive Sleep Apnoea. Such kind of deteriorations are rather rampant (from 3 till 8 percent of population are suffered form them) and exercise a significant influence on human health and patient quality of life. Men suffer from this deterioration 3-8 times more often then women.

Diagnostics of Obstructive Sleep Apnoea usually pursued by time-taking and expensive method in sleep laboratories possessing related diagnostic equipment. This method is required long-lasting registration of number human functions of sleeping patient. Usually registered signals are: breath, snore, breast and abdominal respiratory movements, air flow on expiration, body position, legs movements as well as Arterial oxygen percent saturation, electroencephalogram etc.

Non-contact and remote monitoring of movements, heart rate and breathing frequency effected by bioradioradar will be essential supplement to polysomnological investigations proving comfortability for patients as well as stability of registered data. The above mentioned monitoring will resulted the possibility conducting the prophylactic examinations for determinations breathing and sleep disturbances as well as the same for children, including preventing sudden infant death syndrome.

“Bioradiolacation” / edited. А.Bugaev, S. Ivashov, I. Immorev.

     Published in Bauman Moscow State Technical University, 2010.