Jukka Vanhala

Smart Clothing Prototype for the Arctic Environment

Abstract: Continuous miniaturisation of electronic components has made it possible to create smaller and smaller electrical devices which can be worn and carried all the time. Together with developing fibre and textile technologies, this has enabled the creation of truly usable smart clothes that resemble clothes more than wearable computing equipment. These intelligent clothes are worn like ordinary clothing and provide help in various situations according to the application area. This paper describes the design and implementation of a survival smart clothing prototype for the arctic environment. Concept development, electrical design, and non-electrical features are discussed. The suit provides communication, positioning, and navigation aids for the user. Depending on the measurements of the human and the environment, the suit decides whether an emergency message should be sent. The user can control the system with a user interface called a Yo-Yo. The functionality of the suit has been tested in an arctic environment.

TileTrack: Capacitive human tracking using floor tiles

Accurate, simple and affordable methods for passive indoor tracking of human beings are still missing. In this article, we describe the development of an unobtrusive two-dimensional human positioning system based on low-frequency electric fields. The systems operation is based on measuring the capacitance between multiple floor tiles and a receiving electrode. The presented system is invisible to the user and uses a single-chip solution to measure the capacitances. The implemented system is evaluated with two different types of receiving electrodes and the results are presented. With the used tiles, the system can locate a standing human with at least 15 cm accuracy and track a walking person with at least 41 cm accuracy. The update rate of the system is 10 Hz.

Smart clothing for the arctic environment

New fiber and textile materials and miniaturized electronic components make it possible to create truly usable smart clothes. These intelligent clothes are worn like ordinary clothing providing help in various situations according to the designed application. This paper describes the design and implementation of a survival smart clothing prototype for the arctic environment. Concept development, electrical design, non-electrical features, textile material selection, and clothing design are discussed. Communication and positioning aids have been provided to the suits user. Several human and the environment measurements decide whether an emergency message should be sent. The functionality of the suit has been tested in the arctic environment.

Ultrasonic Power and Data Link for Wireless Implantable Applications

Wireless implantable devices revolutionize the field of biomedical engineering as soon as satisfactory power supplies are conceived. This paper presents a novel ultrasound-based method for powering a battery-free electrical implant. Contrary to the commonly used RF and inductive methods, ultrasonic power transmission helps to avoid problems with electromagnetic coupling and offers for use a selection of data frequencies not limited by national regulations. The proof-of-concept data and power link is based on piezoelectric crystals. Measurements carried out in degassed water brought perspective to the feasibility of an ultrasonic link. Efficiencies of 21-35 % at distances between 5 mm and 105 mm were achieved

Comparison of Center Estimation Algorithms for Heart and Respiration Monitoring With Microwave Doppler Radar

Microwave doppler radar offers significant improvements for unobtrusive heart and respiration measurement. Radar monitoring enables non-contact measurement, through clothing, of heart and respiration rate, which is desired in several applications ranging from medical sleep laboratory measurements to home health care measurements and stress monitoring. The use of high frequency radar (>; 10 GHz) instead of lower frequencies (~2.4 GHz) increases the signal-to-noise-ratio of the signal and enables the utilization of commercial radar modules. However, if high frequency radar is used, linear combining of quadrature radar channels is inadequate. Instead, a nonlinear channel combining algorithm is needed. The combining can be performed with an arctangent function if center, amplitude error, and phase error are estimated accurately and corrected. In this paper, we show that the Levenberg-Marquardt (LM) center estimation algorithm outperforms the state-of-the-art center estimation algorithm precision-wise and is computationally less complex. The simulated results show that the root mean squared error with the LM method is always less than 1%, while it is around 5%-13% with the compared method, depending on the breathing signal model used. In addition, the computational complexity of the LM method stays almost constant as the size of the data set increases, whereas with the reference method, it increases exponentially. In this paper, the LM method is validated both with simulations and with real data.

Design and Implementation of a Portable Long-Term Physiological Signal Recorder

This paper describes a design and implementation of a portable physiological signal recorder. The device is designed for measuring electrocardiography, bioimpedance, and users activity. The bioimpedance measures the dynamic changes in the impedance, and its main application is monitoring users respiration. Activity is measured with three-axis acceleration sensor. During the design, a special attention is paid on the devices power consumption and the target has been set to a 24-h operating time. Functionality of the implemented measurement device is proven with test measurements, which include, e.g., comparison of measurement signals against reference signals, testing the device operation under vigorous upper body movements, and during a light exercise. In order to verify the device operation during real-life activities, one full day, 24-h long, measurement is carried out. The measurement system is tested with both commercial Ag/AgCl gel-paste electrodes and custom-made textile electrodes. Device is proven to be operational with both electrodes, but textile electrodes are found to be more sensitive for movement artifacts. This paper also gives a small review of other existing portable and wearable physiological measurement devices and discusses some general requirements of these devices.

Textile Electrodes in ECG Measurement

Textile electrodes are a new, potential choice for biopotential measurements. In this research different kinds of textile electrodes were compared and good measurement positions were searched. In the first part the properties of four structurally different textile electrodes were compared. Three of the electrodes were industrially manufactured and one was hand-made by embroidering conductive yarn on fabric. Four test persons were used for testing the electrodes. The measurements were made three times with all the four electrode types so that in each measurement the skin was prepared in a different way. Three of the test persons performed a predefined set of motions for five minutes. The purpose of this test was to examine how well the textile electrodes stay put in different positions during movements. The best results were achieved with the embroidered electrodes, which have a large contact area with the skin. According to the measurement results, undisturbed electrode positions are difficult to find. Good positions for one person might not fit for another, because of the different shapes of bodies. In addition, different properties of skin and direction of the axis of the heart may affect the results.

Learning and adaptive fuzzy control system for smart home

Automated smart homes have widely established their position as a research field during the last decade. More and more context sensitive concepts are being studied and at the same time proactivity has broken through in ambient intelligence research. Technology has advanced towards an adaptive and autonomous home, which can take care of the inhabitants’ well-being in numerous ways.

The design and implementation of electrically heated clothing

Modern fibre and textile materials and miniaturised electronic components enable implementation of smart clothes that enhance or augment the functionality of the ordinary clothing. Smart clothes together with palm top computers comprise applications that have an easy to use user interface. The paper describes the design and implementation of the electrically heated clothing prototype. The purpose of the prototype is to study the possibilities to augment the usage temperature range of the clothing by providing an additional electrical heating option. A palm top computer based user interface is also presented and compared to other alternatives. Some disadvantages and improvements are also discussed.

Screen-Printing Fabrication and Characterization of Stretchable Electronics.

This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2 mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag.