Tatsuo Togawa

Physiological monitoring systems attached to the bed and sanitary equipments

The possibility of attaching measurement systems to the bed and sanitary equipments in order to monitor physiological functions in daily life is examined. Preliminary experiments revealed that (1) information about body temperature and body movement during sleep can be obtained from temperature recordings in the bed, (2) electrocardiograms (ECGs) can be recorded in a bathtub through the tap water and (3) heart rate can be estimated by ECGs obtained on the toilet seat.<<ETX>>

Development of an automatic blood sampling system: control of the puncturing needle by measuring forces

For automatic blood sampling to occur, a needle must stop automatically once it is introduced to the blood vessel. Medical technologists can confirm, by the changes in puncturing force, the moment at which the tip of the needle enters the blood vessel. To achieve automatic blood sampling, the authors have attempted to measure the force required to puncture a blood vessel. A device with a force sensor installed inside was developed to measure the force acting on the needle. Experiments involving puncturing of the vena mediana cubiti of 10 volunteers and a rabbit ear vein were performed. A medical technologist was asked to puncture the vena mediana cubiti. In the rabbit experiments, the measuring device was set on an electric-driven linear stage, which was controlled by a personal computer. In the rabbit experiments, a typical peak was observed in the waveform of the puncturing force, and in the volunteer experiments, two typical peaks were observed. It was considered that just after the last peak appeared, the tip of the needle was inserted into the blood vessel. These results have shown that measuring the force at the time of puncturing a blood vessel will be applicable to achieving automatic blood sampling.

The design of an ambulatory physical activity monitor and it application to the daily activity of the elderly

An ambulatory acceleration monitor has been developed, and physical activity was evaluated in the elderly. The ECG, and accelerations at the wrist, waist and ankle were measured. The heart rate and the frequency and amplitude of acceleration per unit time were calculated and evaluated. Both working and retired elderly performed daily activities. The heart rate closely paralleled wrist acceleration. Behavior could be differentiated by the time domain signals. This system may be effective for understanding and describing the characteristic behavior of the elderly quantitatively and objectively.

Preliminary study of calibration-free continuous glucose monitoring with microdialysis technique

To develop an artificial pancreas, measurement of subcutaneous glucose concentration by using a microdialysis technique is required. However, long-term continuous measurement has not been achieved because the microdialysis probe recovery rate and the sensitivity of the glucose sensor decrease. To solve this problem, a new method for long-term continuous measurement of subcutaneous tissue glucose concentration using a microdialysis technique was developed. We assumed a model of standard glucose solutions of two different concentrations, which are perfused via a microdialysis probe inserted subcutaneously. The standard solutions are switched by changing the valve. One solution is higher in concentration than the tissue and the other is lower. By controlling the perfusion time ratio of the standard solutions, we will automatically be able to calculate the glucose concentration of the tissue from the ratio of perfusion time when the glucose sensor signal at the microdialysis probe outlet is steady. In our results, measurement error was less than 10% in the experiment using a larger-scaled hollow fiber instead of a microdialysis probe. This study suggests a method for continuous measuring of subcutaneous tissue glucose concentration without calibration.

Fully automated ECG data acquisition in a bathtub

In apply to home health monitoring, the authors attempted ECG recording in a bathtub. For fully automated data acquisition, a personal identification technique was introduced in which differences in ECG waveforms among individuals were used. The wavelet transform was applied to reduce the ECG data, and a neural network was introduced to create a discrimination algorithm by learning. In a preliminary study, it was shown that more than 91% of ECG data could be identified correctly among a family of five members.

Imaging of thermal inertia to visualize reactive hyperemia in the forearm skin after arterial occlusion

An imaging system has been developed to visualize the effect of reactive hyperemia by measuring skin thermal inertia after releasing arterial occlusion because it was known that thermal inertia depends on the blood flow. The method is based on the ability to calculate thermal inertia from thermographic measurements of the response to a known stepwise change in ambient radiation temperature. Measurements were made during reactive hyperemia after 1 min of complete occlusion. After immediate releasing the cuff pressure, the response of reactive hyperemia appeared in the image of thermal inertia, where many island-shaped nonuniform thermal inertia distributions were observed.

Estimation of the Biphasic Property in a Female’s Menstrual Cycle from Cutaneous Temperature Measured During Sleep

This paper proposes a method to estimate a woman’s menstrual cycle based on the hidden Markov model (HMM). A tiny device was developed that attaches around the abdominal region to measure cutaneous temperature at 10-min intervals during sleep. The measured temperature data were encoded as a two-dimensional image (QR code, i.e., quick response code) and displayed in the LCD window of the device. A mobile phone captured the QR code image, decoded the information and transmitted the data to a database server. The collected data were analyzed by three steps to estimate the biphasic temperature property in a menstrual cycle. The key step was an HMM-based step between preprocessing and postprocessing. A discrete Markov model, with two hidden phases, was assumed to represent higher- and lower-temperature phases during a menstrual cycle. The proposed method was verified by the data collected from 30 female participants, aged from 14 to 46, over six consecutive months. By comparing the estimated results with individual records from the participants, 71.6% of 190 menstrual cycles were correctly estimated. The sensitivity and positive predictability were 91.8 and 96.6%, respectively. This objective evaluation provides a promising approach for managing premenstrual syndrome and birth control.

Estimation of systolic blood pressure variations from pulse arrival time using a narrow-band filter

A narrow-band filtering method was explored to improve the correlation between systolic blood pressure (SEP) and pulse arrival time (PAT). The raw correlation coefficients among them on 15 subjects vary from 0.19 to 0.95. When the uncorrelated components in both signals were suppressed, the remained narrow-band components showed a fairly good linear correlation. The average correlation coefficient was up to 0.87 from 0.69, and the most striking one reached 0.99. The study implies that the narrow-band PAT may be used as a promising indicator of detecting the changes in systolic blood pressure and other physiological characteristics.

A Scalable Healthcare Integrated Platform (SHIP) and Key Technologies for Daily Application

A ubiquitous era has arisen based on achievements from the development of science and technology over the previous 1,000 years, and especially the past 150 years. Among the numerous accomplishments in human history, four fundamental technologies have laid the foundation for today’s pervasive computing environment. The electromagnetic wave theory, established by James Maxwell in 1864, predicted the existence of waves of oscillating electric and magnetic fields that travel through empty space at a velocity of 310,740,000 m/s. His quantitative connection between light and electromagnetism is considered one of the great triumphs of 19th century physics. Twenty years later, through experimentation, Heinrich Hertz proved that transverse free space electromagnetic waves can travel over some distance, and in 1888, he demonstrated that the velocity of radio waves was equal to the velocity of light. However, Hertz did not realize the practical importance of his experiments. He stated that, “It’s of no use whatsoever ... this is just an experiment that proves Maestro Maxwell was right – we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there.” His discoveries were later utilized in wireless telegraphy by Guglielmo Marconi, and they formed a part of the new “radio communication age”. The second fundamental technology is spread-spectrum telecommunications, whose multiple access capability allows a large volume of users to communicate simultaneously on the same frequency band, as long as they use different spreading codes. This has been developed since the 1940s and used in military communication systems since the 1950s. Realization of spread-spectrum technology requires a large computational capacity and leads to a bulky size and weight. Since the initial commercial use of spread spectrum telecommunications began in the 1980s, it is now widely used in many familiar systems today, such as GPS, Wi-Fi, Bluetooth, and mobile phones. This was made possible by the invention of computing machines and integrated circuits, the third and fourth tremendous triumphs. The first automatic computing machine, known as ENIAC, was built using 18,000 vacuum tubes, 1,500 relays, 70,000 resistors, and 10,000 condensers. It performed 35,000 additions per O pe n A cc es s D at ab as e w w w .in te ch w eb .o rg

Improvement of thermal properties imaging system of skin by changing ambient radiation temperature in stepwise fashion

Proposes a system to make images on skin thermal properties such as emissivity, thermal inertia and emissivity-corrected thermography. The properties are estimated to measure the time course of temperature during changing ambient temperature in stepwise fashion. Discharge from huge capacitances to an electrical heater which is controlled by their temperature can heat the ambient radiation from 20 to 40/spl deg/C within 0.2 sec. The time course of temperature on the skin surface is almost linear against square root of time, which fits the theory. We can conclude that the system is practically applicable.