Trine M. Seeberg

ESUMS: A mobile system for continuous home monitoring of rehabilitation patients

The pressure on the healthcare services is building up for several reasons. The ageing population trend, the increase in life-style related disease prevalence, as well as the increased treatment capabilities with associated general expectation all add pressure. The use of ambient healthcare technologies can alleviate the situation by enabling time and cost-efficient monitoring and follow-up of patients discharged from hospital care. We report on an ambulatory system developed for monitoring of physical rehabilitation patients. The system consists of a wearable multisensor monitoring device; a mobile phone with client application aggregating the data collected; a service-oriented-architecture based server solution; and a PC application facilitating patient follow-up by their health professional carers. The system has been tested and verified for accuracy in controlled environment trials on healthy volunteers, and also been usability tested by 5 congestive heart failure patients and their nurses. This investigation indicated that patients were able to use the system, and that nurses got an improved basis for patient follow-up.

Printed organic conductive polymers thermocouples in textile and smart clothing applications

This work reports on an experimental investigation of the potential of using selected commercially available organic conductive polymers as active ingredients in thermocouples printed on textiles. Poly(3, 4-ethylenedioxythiophene): poly(4 styrenesulfonate) (PEDOT:PSS) and polyaniline (PANI) were screen printed onto woven cotton textile. The influence of multiple thermocycles between 235 K (−38°C) and 350 K (+77°C) on resistivity and thermoelectric properties was examined. The Seebeck coefficients of PEDOT:PSS and PANI were found to be about +18 μV/K and +15 uV/K, respectively, when “metal-polymer” thermocouples were realized by combining the polymer with copper. When “polymer-polymer” thermocouples were formed by combining PEDOT:PSS and PANI, a thermoelectric voltage of about +10 μV/K was observed. A challenge recognized in the experiments is that the generated voltage exhibited drift and fluctuations.

Biofouling on protective coatings for implantable MEMS

Protective coatings can replace traditional packaging methods, which are often voluminous and may spoil the otherwise excellent opportunity for miniaturized implantable medical MEMS. The bio-growth on a selection of biocompatible protective coatings (TiO2, DLC and Parylene) was investigated. The model system for evaluation was a diaphragm based acoustic resonator primary designed for fish identification. By detecting the shift in resonance frequency, we wanted to highlight the following; i) does the amount of biological growth vary for the different coatings? ii) if biofouling occurs, is the growth devastating for the device characteristics? We found that the resonance frequency did not change significantly. From this we conclude that the stiffness, represented by the spring constant for the resonating structure, was not affected. This result is of major importance also for other diaphragm based in vivo devices to be, e.g. pressure sensors, ultrasonic imaging devices, and dosage pumps.

Automatic Classification of Sub-Techniques in Classical Cross-Country Skiing Using a Machine Learning Algorithm on Micro-Sensor Data

The automatic classification of sub-techniques in classical cross-country skiing provides unique possibilities for analyzing the biomechanical aspects of outdoor skiing. This is currently possible due to the miniaturization and flexibility of wearable inertial measurement units (IMUs) that allow researchers to bring the laboratory to the field. In this study, we aimed to optimize the accuracy of the automatic classification of classical cross-country skiing sub-techniques by using two IMUs attached to the skier’s arm and chest together with a machine learning algorithm. The novelty of our approach is the reliable detection of individual cycles using a gyroscope on the skier’s arm, while a neural network machine learning algorithm robustly classifies each cycle to a sub-technique using sensor data from an accelerometer on the chest. In this study, 24 datasets from 10 different participants were separated into the categories training-, validation- and test-data. Overall, we achieved a classification accuracy of 93.9% on the test-data. Furthermore, we illustrate how an accurate classification of sub-techniques can be combined with data from standard sports equipment including position, altitude, speed and heart rate measuring systems. Combining this information has the potential to provide novel insight into physiological and biomechanical aspects valuable to coaches, athletes and researchers.

Development of a wearable multisensor device enabling continuous monitoring of vital signs and activity

This paper reports on the development and testing of a wearable device intended as a component in an ambulatory system for health monitoring of physical rehabilitation patients. The device measures heart rate, skin temperature, activity level and posture on the users chest. The wearable device has been run through a set of verification tests and the accuracy has been validated in controlled environment on 12 healthy volunteers. A long term user pilot with 5 congestive heart failure patients and their nurses was performed to test the whole system. The conclusion from the performed tests is that the developed wearable multisensor monitoring device is reliable, accurate, easy to use and fit for the purpose.

An Unobtrusive Wearable Device for Ambulatory Monitoring of Pulse Transit Time to Estimate Central Blood Pressure

There is a clinical need for improved ambulatory, frequent and unobtrusive monitoring of blood pressure and cardiac parameters like systolic time intervals. Truly unobtrusive wearable devices combining impedance cardiography with other sensors may be one possible solution. The IsenseU-BP+ device presented in this article measures single channel ECG, impedance cardiography and photo plethysmography at the chest. The device also measures activity and posture, as well as skin temperature. In this study, we report on the possibility to use these signals to measure pulse transit time for estimating blood pressure changes. Six subjects has been tested. Four of them showed good correlation between PTT and mean arterial pressure while two of the subjects had too low signal to noise ratio in the photoplethysmography signal for good estimation of PTT. Thus these results show that the quality of the raw data is promising for calculating a pulse transit time that shows good coherence with mean arterial pressure.

Protective jacket enabling decision support for workers in cold climate

The cold and harsh climate in the High North represents a threat to safety and work performance. The aim of this study was to show that sensors integrated in clothing can provide information that can improve decision support for workers in cold climate without disturbing the user. Here, a wireless demonstrator consisting of a working jacket with integrated temperature, humidity and activity sensors has been developed. Preliminary results indicate that the demonstrator can provide easy accessible information about the thermal conditions at the site of the worker and local cooling effects of extremities. The demonstrator has the ability to distinguish between activity and rest, and enables implementation of more sophisticated sensor fusion algorithms to assess work load and pre-defined activities. This information can be used in an enhanced safety perspective as an improved tool to advice outdoor work control for workers in cold climate.

Investigations of TiO 2 as a protective coating on diaphragm-based in vivo sensors

The motivation for these experiments has been to investigate the influence of a biocompatible protective coating on diaphragm-based in vivo sensors. The investigated device is a resonator for fish identification. Such a diaphragm-based configuration is also commonly used for pressure sensors. Six passive ID tags with a set of acoustic resonators have been coated with a 12 nm thin TiO2 film by the atomic layer deposition (ALD) technique. The frequency response in the 200 kHz to 400 kHz range has been measured in water before and after coating. The resonance peaks can still be detected after coating, but an increase in the resonance frequencies of about 2 % is measured. The increase is explained by a thicker diaphragm due to the TiO2 film.

Towards a wearable sensor system for continuous occupational cold stress assessment

This study investigated the usefulness of continuous sensor data for improving occupational cold stress assessment. Eleven volunteer male subjects completed a 90–120-min protocol in cold environments, consisting of rest, moderate and hard work. Biomedical data were measured using a smart jacket with integrated temperature, humidity and activity sensors, in addition to a custom-made sensor belt worn around the chest. Other relevant sensor data were measured using commercially available sensors. The study aimed to improve decision support for workers in cold climates, by taking advantage of the information provided by data from the rapidly growing market of wearable sensors. Important findings were that the subjective thermal sensation did not correspond to the measured absolute skin temperature and that large differences were observed in both metabolic energy production and skin temperatures under identical exposure conditions. Temperature, humidity, activity and heart rate were found to be relevant parameters for cold stress assessment, and the locations of the sensors in the prototype jacket were adequate. The study reveals the need for cold stress assessment and indicates that a generalised approached is not sufficient to assess the stress on an individual level.

Stretchable Conductors Enabled by Metal Coated Polymer Spheres

This paper presents a novel concept for stretchable conductors. Metal coated polymer spheres were densely packed in biocompatible silicone tubes. The resistivity of the conductors were in the approximate range of 1×10-4 Ωm at 0% strain and 50% strain could be applied before degrading their electrical performance. Initial results showed good reproducibility and no drift in resistance values up to 1000 cycles with 0%-25% strain. This make the conductors well suited for digital low speed data transmission. The initial application is intended for integration of electronics in clothing; the conductors have been tested with success transmitting data from a commercial digital combined humidity and temperature sensor.