Naoto Kakuta

Human thermal models for evaluating infrared images

Discusses comparing infrared images under various thermal environmental conditions through normalization of skin surface temperature. To evaluate IR images obtained under various thermal environmental conditions, we proposed a human thermal model with which IR images obtained under certain thermal environmental conditions can be converted into images under other conditions. The model was based on a numerical calculation of the bio-heat transfer equations that express heat transfer phenomena within the human body. A 16-cylinder-segment model was used as the geometry of the human body. Comparisons of IR images with their converted images indicate that this method is effective in eliminating the influence of the thermal environmental conditions. However, the difference between the converted images and the original ones varies among segments. In future work, we will use this method to investigate the IR images of several subjects under various thermal environments.

A master-slave manipulation system with a force-feedback function for endoscopic surgery

A master-slave manipulation system with a force-feedback function was developed for endoscopic surgery. The slave manipulation system, which is located at the head of a robot arm system, uses a forceps system which is capable of being opened and closed by a DC motor-driven arrangement. The master manipulator involves a mechanical link system which has the same structure and scale as the slave robot-arm system. The value of this system was verified experimentally using a bench-test system with one degree of freedom which has the same force-feedback mechanism as the master-slave manipulation system. Although the system became oscillatory and unstable when the master manipulator was operated using a force feedback system (simple force reflection servo controller), it was possible to make the system stable improving the force feedback system by adding impedance term (improved force reflection servo controller).

Thermal rhythmography-topograms of the spectral analysis of fluctuations in skin temperature

It has been reported that skin blood flow and, consequently, skin temperature exhibit several periodic fluctuations. Although the mechanisms and physiological basis underlying these fluctuations are not yet well understood, it is thought that the fluctuations originate in the periodic rhythms of the autonomic nervous system. In this study, a program for a far-infrared thermal imaging system was developed which is capable of displaying topograms of the power spectra of an arbitrary frequency range with respect to changes in skin temperature (i.e. thermal rhythm). Thermographic images were taken using a high-speed far-infrared thermal camera. The change in the skin temperature with respect to time at every pixel was obtained from the time series of the thermograms, and the power spectrum was calculated by the FFT method using the personal computer. The amplitude of the power spectrum at an arbitrary frequency range was changed into pseudo-colors at each pixel, and a 2-dimensional or 3-dimensional color image of the amplitude mapping of the power spectrum at each frequency range was obtained. We are now analyzing differences between healthy subjects and patients with Raynauds syndrome in the distribution of the rhythms of skin temperature using this system.

Near-infrared measurement of water temperature near a 1-mm-diameter magnetic sphere and its heat generation rate under induction heating

This paper presents a method of measuring the temperature of water near a 1-mm-diameter magnetic sphere under induction heating. The method is based on the temperature dependence of the absorption coefficient of water at a wavelength of 1150u2009nm. In this study, two-dimensional images of the absorbance, which is the transverse projection of the absorption coefficient of water, were acquired by a near-infrared camera through a telecentric lens, and three-dimensional radial profiles of the temperature were then generated by applying inverse Abel transforms (IATs) to the absorbance profiles. To ensure the spherical symmetry of the temperature and the parallelity of the light rays, which are the conditions necessary to apply an IAT, the onset of free convection and the angles of deflection were evaluated. This paper also presents a method of estimating the heat generation rate in a sphere by fitting the numerical solutions of the thermal conduction equation to the measured temperatures. The temperatures and hea...

Diamond-like carbon coating on micropipettes

Based on glass micropipettes which are widely used in bioengineering and medicine, various microsensor probes could be produced by recent microfabrication techniques. Conductive surfaces of these sensor probes mostly need electrical insulating films coated on them, but it has been difficult to coat a high-quality and strong insulating film on a microacute probe such as a micropipette, especially on its tip. Therefore, we have employed diamond-like carbon (DLC) as an insulating film and developed a DLC coating method based on plasma chemical vapor deposition method. In the deposition apparatus, the cathode is the micropipette itself and the anode is a mesh cylinder with a central focus on the micropipette. In order to prevent the growing films from transformation due to high temperature at the tip, the voltage between the pair of electrodes is impressed intermittently. Raman spectrum and electrical resistivity measured here indicate that the deposited film is DLC and it can be worked well as an insulating film. The DLC coating method could be useful in microprobe fabrications.

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This technique utilizes wavelengths of 1150 and 1412 nm, at which the absorption coefficient of water is dependent on temperature. Water or a non-turbid aqueous gel containing a 2.0-mm- or 0.5-mm-diameter magnetic sphere is irradiated with 1150 nm or 1412 nm incident light, as selected using a narrow bandpass filter; additionally, two-dimensional absorbance images, which are the transverse projections of the absorption coefficient, are acquired via a near-infrared camera. When the three-dimensional distributions of temperature can be assumed to be spherically symmetric, they are estimated by applying inverse Abel transforms to the absorbance profiles. The temperatures were observed to consistently change according to time and the induction heating power.