Evaluation of weight sensation should be performed by a physical measurement which also relates to the subjective evaluation. It, therefore, is necessary to find a new method of physical measurement.
This study has shown the relationship between the weight sensation and the electric signal (electromyogram : EMG) generated in a living body.
Stevens' power law is
R=kSⁿ
where our experiments show that n=1, if R is the EMG, k is a constant, and S is the stimulation level (weight load S≥1000 g). The value of the constant k is dependent on the finger (e. g. k=1.6×10^-2μV at thumb finger and k=7.4×10^-2 μV at middle finger).

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The epicardial breakthrough can be recognized from the localized lowering of the body surface potential, which is characterized by a concave figure of the equipotential lines or a second-minimum on the isopotential maps. Recognition of epicardial breakthrough enables us to diagnose location of the block site of the bundle branch blocks more precisely than by the use of ECG or VCG. However, it has not been determined as to how long an interelectrode distance is appropriate to detect such a localized potential. In the present study, influence of the interelectrode distance on the characteristic patterns reflecting the epicardial breakthrough was examined with respect to 16 healthy persons by using three kinds of 9 x9 array electrode with interelectrode distances of 1.25 cm, 5×5 with 2.5 cm, 3×3 with 5 cm, respectively.
Breakthrough was recognized in 15 out of 16 cases (94%) on maps recorded with electrode arrays at interelectrode distances of 1.25 cm and 2.5 cm. However, it was possible to recognize the breakthrough in only 10 out of 16 cases (63%) with the electrode array at the interelectrode distance of 5 cm.
Conclusion It is prefarable to use electrode arrays within interelectrode distance of at least 2.5 cm for purposes of the breakthrough recognition.

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This paper describes a new multielectrode probe structure which is produced on the basis of IC techniques. A tungsten (W) electrode lead array is defined on an insulated silicon supporting carrier and is insulated from the surrounding tissue fluid by Si₃N₄ film formed by chemical vapor deposition. W is chosen from the viewpoint of durability in high temperature process of Si₃N₄ deposition. A small and mechanically strong silicon carrier having clearly shaped outline and gradual taper is produced by a combination of anisotropic and isotropic etchings. The recording area of a microprobe is formed by vacuum evaporation of gold used as the base for platinum plating for lowering the electrode impedance. Output wires are soldered onto the copper contact pads. The probe tips are 30 μm wide for a single electrode and 90 μm for a 4-channel multielectrode.
Electrode impedance characteristics of the thin film W, Au and platinum-plated electrodes are nearly the same as the conventional metal microelectrodes having the same recording areas. Calculation of the parasitic capacitances associated with the probe structure makes prediction of signal attenuation and interelectrode crosstalk possible. This microprobe has about 7% signal amplitude loss and about 1% crosstalk.
Photo-induced noise arising from the photovoltaic effect is successfully diminished to a negligible value by insulating silicon carriers from the electrolyte with thermally grown SiO₂.
The microprobes are competent for recording simultaneously from a single cell and cell groups in the brain of a cat.

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Metallic electrodes are employed as biomedical sensing electrodes. However, biomedical signals are distorted in case of metallic electrodes due to the noise generated by the electrochemical reaction between metal and electrolyte. The present study concerns introduction of a dielectric silicon nitride film between electrolyte and electrode in order to minimize the effects of noise and facilitate biomedical signal detection.
The silicon nitride (Si₃N₄) film was deposited on a silicon substrate by the process of vapor phase growth of SiH₄ and NH₃ at 950°C. The silicon substrate was of 0. 001 ohm-cm N-type silicon, 0..25, mm thick, (111) oriented, and chemically polished to a mirror finish. The relative flow rates were as follows SiH₄ 5 ml/min, NH₃ 1 ml/min, H₂ 3. 51/min and H₂ was used as a carrier gas.
The typical current-voltage characteristics in positive and negative directions of a Au-Si₃N₄, , . (1 000Å thick, 50 mm² area) -Si structure at room temperature and at a low field are virtually identical and ohmic. The impedance Z_o of this film can be easily transformed into parallel equivalent circuit of the resistance Z_R and the reactance Z_c. Z_c is much larger than Z_R from ultra low frequency to 10 Hz. Z_R is much larger than Z_c from 10 Hz and above. Therefore, when the frequency is lower than about 10 Hz, Z_o is resistive. When the input impedance of the amplifier is high, DC signal can be also detected. Noise level between this electrode (80 mm² area) and calomel reference electrode in 0.9% saline solution is much lower than the case in which calomel reference and other electrodes (thermal silicon oxide film, etc.) are combined. This electrode is stable and has the same noise level as the Ag-AgCl electrode (disk type). It was designed for EEG but it could be used for ECG and EMG as well.

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This paper describes the automatic recognition method which classifies the respiratory sounds into seven categories : vesicular, bronchial, sonorous, sibilant, coarse rale, fine rale and medium rale. This method enables automatic auscultation which will improve mass survey and screening tests of the respiratory diseases. In order to analyze sound data, which were obtained from patients with an improved electret microphone, three calculation processes were adopted and examined : FFT, auto-regressive linear prediction (AR), moving average linear prediction (MA), where sampling time was 200 or 250 μsec.
The tests showed the MA process to be the best, and applicable even to mixed respiratory sounds. However as this calculation was often too difficult to converge into a clear solution, an approximate MA process was developed to render calculations easy enough for practical use.
Multivariate normal density functions were used to classify the data because each typical respiratory sound showed almost normal distribution. About 30 samples of isolated respiratory sounds were correctly classified into the seven distinct categories. Except for the following combinations, more than 40 samples of the artificially mixed respiratory sounds using R. Murphy's medical training tape were separated and classified : (a) sonorous and rale (medium, coarse, fine), and (b) sibilant and fine rale.
Conclusion : this method is applicable of mass survey and screening tests of respiratory diseases.

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In scoliosis the characteristic deformity of the spine has two basic structural changes : one is lateral flexion and the other is axial rotation. X-ray examination has been used to detect these structural changes. Cobb's method has proved satisfactory to measure lateral flexion deformity, but there has been no satisfactory method to measure rotational deformity either by X-ray examination or other method.
We have developed a method to measure this rotational deformity by drawing out cross sections of the trunk. In our method the projection of horizontal laser beam on the body surface is caught with an inclined line, sensor camera. Turning both the laser and the line sensor camera around the patient, output data of the camera are converted into graphic display or drawing by X-Y plotter through minicomputer.
To evaluate quantitatively deformation of cross sections of patients, indices of deformation have been defined and algorithms to calculate these indices have been proposed. Using these indices of deformation, data of cross sections of about 60 patients have been analyzed.

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This system is designed for the measurement of human respiratory response. This system has two kinds of functions. One is to control concentration of agent gas which is supplied to the subject and the other is to measure the respiratory response of the subject due to the change of inhaled gas contents.
The main apparatus is divided into two systems, the mechanical system and the electronic system. The mechanical system mixes air and agent gas to be supplied to the subject. The electronic system based on microcomputer controls gas contents and gathers data on the subject.
Air and agent gases are reserved in tanks at high pressure 100 kg/cm²-150 kg/cm². Either CO₂ or N₂O may be selected for purposes of experiment and mixed by means of the gas mixer. In the decompression area, the pressure of those gases are set to 8 kg/cm²-10 kg/cm² and they are sent to the mixing box through the control valve. Mixed gas which is supplied from gas mixing box flows into decompression area of the second stage. This stage supplies the gas of about 1 atm or a little higher pressure to the subject. The concentration of the agent gas during inspiration is checked every 0.1 second and compared with the program of gas concentration.
Signals from microcomputer are sent to the pulse motor which controls the valve. The measuring circuit checks the concentration of agent gas according to the program and samples a few kinds of data, such as inspired gas concentration, expired gas concentration, flow volume of expired gas, heart rate, etc. One of the experiments on 5% CO₂ inhalation showed, the process of wash-in and wash-out of carbon dioxide of the subject.

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This paper describes techniques for RI image processing with a microprocessor. The data measured by an imaging system are either written on a paper tape or on a cassette magnetic tape. The data are blurred by the low resolution of a detector or by a lot of noises. The improvement of the image quality is achieved with the filter based on the fast Hadamard transform (FHT). The hardware consists of a microprocessor, random access memory unit (RAM), cassette magnetic tape unit (CMT), paper tape reader (PTR), paper tape punch (PTP), CRT display and a graphic display which is external. The I/O devices are connected to the microprocessor via their own interfaces. The data are fed into the RAM through the PTR or the CMT, and are processed by the microprocessor under the control of a series of image processing programs in the form of a subroutine. These consist of algorithms of the filter based on the FHT, those of a 9 points smoothing, etc. The processed data are punched on paper tape with the PTP. For accurate diagnostic use, they are represented three-dimensionally on the graphic display, using punched tapes as a media.
Because the FHT deals with only real numbers and is performed by the additions and subtractions of fixed point data; the filter based on the FHT is advantageous both in computation time and in memory capacity.
Finally, application of this method to a clinical case is provided.

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