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Electrical Engineering

Body heat

Equipment detects temperature variations by way of infrared radiation

When fevers, infections or pains cannot have their cause immediately defined, this is when more precise exams are needed to decipher these symptoms and to discover the origin of any illness. One of the ways of making this diagnosis is to measure the temperature of the body by way of infrared radiation. According to the temperature variation in determined parts of the body, it is possible to verify the incidence or not of debilitating factors in the organism. This variation is detected by a thermographic camera that registers the radiation and then transforms it into a thermal image capable of representing, point by point, the surface temperature of a body. The equipment assists in the detection of illnesses such as cancer, leprosy, diabetes, lesions caused by repetitive stress injuries  (RSIs) and other inflammatory situations, and can even be used in sports medicine. These cameras, which also measure the temperature of industrial equipment, are widely used in some countries, but as yet little used in Brazil due to their high cost. This is a situation that is beginning to change through the work of researchers at the Physics Institute of the University of Sao Paulo in Sao Carlos (IFSC/USP). They have built, for the first time in the country, two prototypes of a thermographic camera capable of carrying out exams at a distance and of a non-invasive mode.

At the size of a conventional video camera, which should facilitate its use in hospitals, health centers and clinics, the equipment developed, with FAPESP’s financial support,  captures the images based on a single sensor, in which each point of focused heat is codified by a color standard. In order to detect the images, two mirrors move in a synchronized manner in different directions, vertically and horizontally, making a complete sweep over all of the points of image to be registered. Captured by the object lens of the camera, the infrared radiation is reflected in the mirrors, arriving at the sensor by way of a lens totally transparent to this type of electromagnetic wave. The camera is linked to a computer and the captured images are saved and analyzed by a piece of software, also developed at the laboratory.

With the exception of the sensor, imported and without something nationally similar, all of the thermographic camera’s items were manufactured in Brazil. It is prepared to measure temperatures between 18°C and 40°C, variations existing on the skin of the human body. To guarantee this performance, there is a calibration method with controlled standards of temperature and that was also developed by the group. This calibration guarantees the sensitivity to 0.1ºC within the band used for health applications. For industrial use, it could be programmed to measure temperatures in much higher bands, up to 1,000ºC.

Technological domination
According to Luiz Antônio de Oliveira Nunes, who coordinated the research in the Lasers and Applications Laboratory of IFSC/USP, the thermographic camera cannot be patented, because innovating technology does not exist within it, only the mastery of the technology, that has already been published and is public.  “Our camera is not a copy, the project is ours and novelties exist, but they do not justify a patent. Our strategy is to master imported technologies, commercially available, but as yet not produced in the country. After dominating the technology, we want to produce it on an industrial scale”, he reveals. The national camera has no timescale to reach the national market because as yet it is not established who is going to manufacture it.  Nunes is looking for partnerships with companies in order to turn the production viable. The cost of the camera is still expensive, around US$ 10,000.00, but is a price one third of that of a similar imported model.

The market for this type of equipment is hospitals, health clinics and even airports. In the area of clinical esthetics, the incidence of cellulite could be better evaluated with thermographic cameras, that show where the flux of heat id blocked by fat, even for problems just starting. Another possibility is veterinary use. “For example, if a race horse has a muscular problem, one will only need to photograph it with the camera to know its true conditions for a race.”

All of the tests with the camera were performed at the laboratory level, with infrared from the IFSC/USP itself, under the guidance of the medical doctor Antonio Carlos de Camargo Andrade Filho, from the Lauro de Souza Lima Institute of Bauru, who specializes in pain therapies. “The clinical teats have already been concluded and have proved that the camera helps in diagnostic analysis both for unknown pains and for skin illnesses and superficial tumors, as well as allowing for accompanying the vitality of the skin”, Dr. Andrade Filho advised.

Industrial use
As well as medical use, this type of technology also allows for the evaluation of thermal loses in machinery and installations, improving the performance of equipment in use or under development in industry. For this reason, contrary to what occurs in the medical area, in industry thermographic technology is already widely used. Measurements in electrical panels of force fields, for example, reveal loses of energy very often brought about by a simple poor contact (the higher the temperature the greater the energy loss).

In the automobile industry the equipment could verify if heaters and the windscreen demisters have been well installed. In steel making it could reveal a leak of heat in the high temperature furnaces, in plants, boilers, and refrigeration systems. In the Armed Forces thermographic cameras are used in high precision equipment, principally installed in military aircraft. The military application of thermography began back in the 1940’s, and that of medicine in the 1960’s. The first infrared camera was developed in 1948 and was capable of registering an image after twenty (20) minutes. The camera developed at the IFSC/USP makes an image in only three seconds, but a camera with military application is already capable of registering up to one thousand images per second.

The Project
Development of a thermographic camera
Regular Line of research Assistance
Luiz Antônio de Oliveira Nunes – IFSC/USP
R$ 49,000.00 and US$ 12,490.00 (FAPESP)