Claudine Gehin

Flexible technologies and smart clothing for citizen medicine, home healthcare, and disease prevention

Improvement of the quality and efficiency of healthcare in medicine, both at home and in hospital, is becoming more and more important for patients and society at large. As many technologies (micro technologies, telecommunication, low-power design, new textiles, and flexible sensors) are now available, new user-friendly devices can be developed to enhance the comfort and security of the patient. As clothes and textiles are in direct contact with about 90% of the skin surface, smart sensors and smart clothes with noninvasive sensors are an attractive solution for home-based and ambulatory health monitoring. Moreover, wearable devices or smart homes with exosensors are also potential solutions. All these systems can provide a safe and comfortable environment for home healthcare, illness prevention, and citizen medicine.

Resonant force sensor using a PLL electronic

The working principle of resonant force sensors with double ended tuning forks (DETF) consists of measuring one of the resonant frequencies of the vibrating beams which depend on the force applied in the beams. Although the principle is simple, its practical application presents some problems. The principal difficulties in the design of such a structure lie in two principal points dealing with the mounting of the DETF on its support and with the mechanical resistance of the structure. In order to approach the ideal structure, the proposed force sensor is based on a DETF directly machined in a metallic circular plate. The force to be measured is applied on the plate by using a tube. The sensor has been designed using finite element simulations. An electronic circuit including both analog PLL and logic circuitry parts has been developed for frequency shift measurement, dedicated to this sensor. A prototype has been realized and tested which gives promising results; the principal technical features of the prototype are reported.

Wearable Medical Devices Using Textile and Flexible Technologies for Ambulatory Monitoring

Health smart clothes are in contact with almost all the surface of the skin offer large possibilities for the location of sensors for non invasive measurements. Head band, collar, tee-shirt, socks, shoes, belts for chest, arm, wrist, legs ... provide localization with specific purpose taking into account their proximity of an organ or a source of biosignal, and also its ergonomic possibility (user friendly) to fix a sensor, and the associated instrumentations (batteries, amplifiers, signal processing, telecom, alarm, display ...). Progress in science and technology offers, for the first time, intelligence, speed, miniaturization, sophistication and new materials at low cost. In this new landscape, microtechnologies, information technologies and telecommunications are a key factor. Microsensors:Microtechnologies offer the possibility of small size, but also intelligent, active device, working with low energy, wireless and non invasive or mini invasive. These sensors have to be thin, flexible and compatible with textile, or made using textile technologies, new fibers with specific properties: mechanical, electrical, optical... The field of applications is very large, e.g. continuous monitoring on elderly population, professional and military activities, athletes performance and condition, and people with disabilities. The research are oriented toward two complementary directions: Improving the relevancy of each sensor and increasing the number of sensors for having a more global synthetic and robust information

A wearable, low-power, health-monitoring instrumentation based on a programmable system-on-chip TM

Improvement in quality and efficiency of health and medicine, at home and in hospital, has become of paramount importance. The solution of this problem would require the continuous monitoring of several key patient parameters, including the assessment of autonomic nervous system (ANS) activity using non-invasive sensors, providing information for emotional, sensorial, cognitive and physiological analysis of the patient. Recent advances in embedded systems, microelectronics, sensors and wireless networking enable the design of wearable systems capable of such advanced health monitoring. The subject of this article is an ambulatory system comprising a small wrist device connected to several sensors for the detection of the autonomic nervous system activity. It affords monitoring of skin resistance, skin temperature and heart activity. It is also capable of recording the data on a removable media or sending it to computer via a wireless communication. The wrist device is based on a Programmable System-on-Chip (PSoCTM) from Cypress: PSoCs are mixed-signal arrays, with dynamic, configurable digital and analogical blocks and an 8-bit Microcontroller unit (MCU) core on a single chip. In this paper we present first of all the hardware and software architecture of the device, and then results obtained from initial experiments.

EmoSense: An Ambulatory Device for the Assessment of ANS Activity—Application in the Objective Evaluation of Stress With the Blind

Analysis of autonomic nervous system activity is a subject of increasing interest in the fields of health care and handicap management, as it provides information on the emotional, sensorial, and cognitive states of the patient. In this context, the simultaneous measurement of several physiological signals using small, discreet, mobile devices is required, in order to unobtrusively obtain such information under real-life conditions. We have therefore developed an ambulatory device which enables the measurement of heart rate, electrodermal activity, and skin temperature with noninvasive sensors. Wireless communication and local data storage on a memory card enables the device to be used during in-situ experiments for the analysis of autonomic nervous system activity. We have used this instrumentation in a study for the objective evaluation of stress in the blind when walking in urban space, through the analysis of electrodermal activity of blind pedestrians who independently followed a charted course involving a range of urban conditions. Experimenting in real-life settings has lead to the definition of novel, more pertinent parameters for the analysis of physiological signals in the study of autonomic nervous system activity. Results from these experiments have identified, for the first time, some rather surprising obstacles or events which give rise to an increased stress for the blind. These results were very encouraging for the use of such ambulatory devices for experiments under real- life conditions.

Which techniques to improve the early detection and prevention of pressure ulcers

Pressure ulcers are a serious health problem for people with mobility disorders, like elders in acute care, long-term care, and home care settings. It also concerns paraplegics, tetraplegics or persons with burned injuries. Pressure ulcers result in significant morbidity and mortality. Consequences are a high human suffering, with high cost in terms of treatment. Several risk factors have been identified for the development of pressure ulcers: they are classified into extrinsic and intrinsic factors. Extrinsic factors include interface pressure, shear forces, friction. Intrinsic factors are the nutritional state of the patient, its age, diseases. There is little information about the mechanism of the formation of pressure sores but it is agreed that it is a complex process. The difficulty of the prevention lies in the evaluation of these factors. It is an essential stage to optimize the preventative measures. Actually, no quantifiable parameters exist to predict the formation of a pressure ulcer. This article is aimed to propose new techniques developed for the early detection of pressure ulcers. First, extrinsic parameters as the interface pressure and its consequences on the mobility are investigated. A new actimeter is presented to monitor the movements of the patient. The second part is dedicated to the presentation of a new imaging technique which can help the physician to control tissue elasticity of the patient. The technique is called elastography, it is a 3D strain estimation of soft biological tissues. Finally, the last way of investigation is the combination of extrinsic and intrinsic factors evaluation for a most relevant earlier diagnosis. Before the description of these techniques, it is essential to understand the phenomenology associated to the development of pressure sores. Only in this way, new techniques can be developed

Infrared Imaging Analysis for Thermal Comfort Assessment

Skin temperature is a relevant and effective indicator for objective evaluation of human sensations and thermal states according to the surrounding thermal stresses. Managed by skin blood flow, sympathetic nervous system (constriction and sweating), subcutaneous thermal structure and facial vein patterns, facial coetaneous temperature variability can give information non-invasively on many physiological functions. These informations are deduced from thermal images obtained by far infrared imaging (7 - 14 mum). The work presented here deals with facial thermographic image analysis. Thermal regions of interest are extracted, such as left and right front, left and right cheek, left and right periobital region. Each region is analyzed by the FFT power spectrum calculation regarding to specific spectral band.

An integrated platform to assess driver's physiological and functional states

Physiological signals like Heart Rate, Respiration and Skin Resistance are relevant indicators to evaluate drivers mental state.

Photolithographic structuring of stretchable conductors and sub-kPa pressure sensors

This paper presents a novel method to prepare stretchable conductors and pressure sensors based on the gold/polydimethylsiloxane (PDMS) system. The gold films were sputtered onto structured PDMS surfaces produced with a photolithographic surface treatment with the aim of reducing tensile strains in the gold film. Scanning electron microscopy (SEM) and atomic force microscopy analyses showed that these 3D patterns reduce cracks and delaminations in the gold film. Electrical measurements indicate that the patterns also protect the films against repeated tensile cycling, although the un-patterned samples remained conducting as well after the completion of 120 cycles. The extrapolated resistivity value of the patterned sample (4.5 × 10 −5 � cm) compares well with previously published data. SEM micrographs indicate that the pattern features deflect the cracks and therefore toughen the gold film. However, x-ray photoelectron spectroscopy and contact angle analyses indicate that the patterning process also slightly modifies the surface chemistry. This patterning method was used to prepare capacitive strain gauges with pressure sensitivity (� Z/Z)/P of 0.14 kPa −1 in the sub-kPa regime. Such stretchable and potentially conformal low-pressure sensors have not been produced before and could prove advantageous for many smart fabric applications. (Some figures in this article are in colour only in the electronic version)

Biomedical Sensors for Ambient Assisted Living

The percentage of the population classified as being elderly has been predicted to increase dramatically in size over the next 30-40 years. Figures produced by the World Health Organisation (WHO) anticipate an increase from around 600 million in the year 2000 to close to 2 billion by the year 20501. By 2050, 22% of the world’s population will be over 602 in Europe it will be over 30%3. In addition, according to the WHO, approximately 10% of the population experience some form of disability. Already 21% of people above the age of 50 have severe vision, hearing and/or mobility problems.