Health Monitoring System in the Bedroom using ... - UbiComp

Health Monitoring System in the Bedroom usingUbiquitous TechnologyJong Min ChoiInterdisciplinary Program in BiomedicalEngineeringSeoul National University, Seoul, Korealeson@bmsil.snu.ac.kr82-2-740-8585Kwang Suk ParkDepartment of Biomedical Engineering, College ofMedicineSeoul National University, Seoul, Koreakspark@bmsil.snu.ac.kr82-2-760-3135ABSTRACTAdvances in information technology have enabledubiquitous health monitoring at home, which is particularlyuseful for patients, who have to live alone. We havefocused on the automatic and unobtrusive measurement ofbiomedical signals and activities of patients. We haveconstructed wireless communication networks in order totransfer data. The networks consist of Bluetooth andWireless Local Area Network (WLAN). In this paper, wepresent the concept of a ubiquitous-Bedroom (u-Bedroom)which is a part of a ubiquitous-House (u-House) and wepresent our systems for ubiquitous health monitoring.INTRODUCTIONUbiquitous health monitoring allows biomedical signals tobe measured without the individual’s awareness. Forsuccessful ubiquitous monitoring the biomedical signalsneed to be measured unobtrusively and the data need to betransferred using a wireless communication system.Biomedical signal measurement is very important in thefield of telemedicine and health monitoring because it is theprecursor of analysis and diagnosis. In previous studiesunobtrusive biomedical signal measurement was not a mainissue. M. Ishijima[1] presented a method to measureElectrocardiogram (ECG) in bed without any body surfaceelectrodes. Instead of body surface electrodes, conductivetextile electrodes were used in order to measure ECG signal.T. Tamura et al.[2] showed that it was possible to obtainECG signal in the bathtub only using water.Bluetooth communication technology has many advantagesfor the field of telemedicine. A lot of data has to betransferred and processed because biomedical signals,activities and environmental parameters are always beingmonitored. Wireless Local Area Network (WLAN) isneeded in association with Bluetooth communicationnetwork. Using Bluetooth technology and WLAN, anyproblems regarding bandwidth and speed can be solved.In this paper, we describe ubiquitous health monitoringsystem in the bedroom. We have focused on theunobtrusive biomedical signal measurement and wirelessdata transfer using Bluetooth technology and WLAN. Thesetwo main technologies have enabled ubiquitous healthmonitoring without patient’s awareness.MATERIALS AND METHODSThe ubiquitous-House (u-House) has a toilet, kitchen, livingroom, and three bedrooms. Sensors are installed in eachlocation. In the bedroom, there are five sensors whichmeasure biomedical signals, activities and environmentalparameters.Fig. 1 Diagram of the ubiquitous bedroom and location ofsensorsA. Unobtrusive Biomedical Signal MeasurementIn the bedroom, three biomedical signals can be measuredfrom the bed.1) ECG signal measurement on bedAn ECG signal can be obtained from the patient in bedusing a conductive sheet. Whenever the patient lies on bedat night, ECG signals are measured by a conductive textileelectrode attached to the bed sheet. In order to process theECG signal an amplifier has been developed. This bioamplifierhas several filters, namely a low-pass, notch, andhigh-pass filter. Such filters can remove noise and it ispossible to obtain a clear ECG signal comparable to thecommon Ag-AgCl direct contact electrode.2) Body movement during sleepBedLoadcell Conductive Sheet Snoring SensorMagnetic SwitchTemperature SensorDoor1

During sleep, the patient moves around. The movement ofpatients can reflect their health. To analyze their health,movement needs to be measured. The four compressiontype load cells[3] which have been attached to the legs ofthe bed can measure these movements.3) Snoring detection during sleepThe number of patients who suffer from severe snoring hasbeen increasing. It is necessary to detect snoring and assesshow long he/she snores during sleep. Snoring detectionequipment uses an electret condenser microphone andRMS-to-DC converter.B. Activities and Environmental Parameters MonitoringActivity monitoring can be beneficial for elderly peoplewho live alone at home. If a medical doctor has ordered apatient to do exercise such as wandering around at home, itis possible to monitor whether he/she does exercise or not.Attaching a magnetic switch to a door makes it easy to findout whether the door has been opened or not.There are several parameters regarding the environmentsuch as temperature, humidity, noise, and illumination. It isimportant to monitor these parameters continuously for thepatients. It is possible to measure room temperature using athermistor which is a kind of variable resistor. Theresistance of thermistor decreases as the increase oftemperature.C. NetworksThe Wireless communication has enabled unobtrusivehealth monitoring. Lots of wires in the bedroom can annoypatients. A Bluetooth network has been used for thepurpose of transferring data from the sensor to theBluetooth access point[4] and a WLAN has also been usedfrom the Bluetooth server to the Home server. For theWLAN, a Personal Digital Assistant (PDA) has beeninstalled in each bedroom.MagneticSwitchRoomECG onBedSnoringSensorD. Data Processing UnitBT APPDA with WLANWeightFig. 2 Diagram of the data transferMainServerFor data processing and transfer, a small data processingunit has been developed. It consists of three parts – power,microcontroller and Bluetooth module.This processing unit can do Analog-Digital Conversionwith a 10bit resolution. Analog signals can be digitized andtransferred to the Home server which collects and analyzesthe data. In our successive studies, this processing andtransfer unit will be used and modified.6VACAdaptorExternalPower5VDC-DCConverterBT ModuleAVR4433ADC inputs(2ch)Fig. 3 Diagram of the data processing unitDISCUSSION AND CONCLUSIONSThere are a lot of sensors which can measure biomedicalsignals, activities and environmental parametersunobtrusively. Among them, just a few sensors were usedin our installation. In the future, other useful sensors will beused in experiments. For body fat measurement, a methodwhich can estimate bio-impedance will be applied. Inaddition, infrared sensors will be used for movementdetection and humidity sensors also will be used forhumidity monitoring. Other sensors can be easilyincorporated into our system because we have alreadydeveloped the small-size data processing and transfer unit.We have not done sufficient experiments on elderly people.In this paper, the experiments should be consideredpreliminary and more data is needed.Unobtrusive biomedical signal measurement and datatransfer via wireless communication has enabled ubiquitoushealth monitoring. Just sleeping on bed and walking aroundthe room allows measurement of some biomedical signals.In addition, activities of patients and environmentalparameters such as temperature can be recorded withoutany notice of the patients.REFERENCES1. M. Ishijima, Monitoring Electrocardiogram in bedwithout body surface electrode, IEEE Transactions onBiomedical Engineering, 1993;40(6):593-5942. T. Tamura, T. Togawa, M. Ogawa, M. Yoda. Fullyautomated health monitoring system in the home,Medical Engineering and Physics, 1998;20:573-5793. CAS Co. LTD http://www.cas.co.kr4. Initium Co. LTD. http://www.initium.co.krProgramDownloadGND3cm2