A low pressure on-chip injection strategy for high-performance chip-based chromatography.

A microfluidic device for high-performance liquid chromatography is presented. The borosilicate glass chip includes a common cross-channel injector and a column chamber. The column chamber comprises two constrictions (10 µm) to retain the chromatographic particles via the keystone effect. A packing channel was utilized to introduce the particulate material (3-µm). This channel has been sealed permanently via laser-assisted photopolymerization avoiding dead volumes within the chromatographic pathway. A sampling strategy is presented enabling the directed definition of the sample plug on-chip. The injection process is studied via video microscopy and chromatographic separations of test solutes with fluorescence detection. Our approach, based on on-chip flow splitting, allows the usage of traditional, economic and robust HPLC instrumentation avoiding the need for sophisticated nano-flow equipment. The performance of the chip device and the injection process was demonstrated by reversed-phase chromatographic separations of a mixture of polycyclic aromatic hydrocarbons achieving constant high efficiencies for the chromatographic signals over the whole elution window.

Coarsening kinetics in demixed lead borate melts.

Lead borate melts have been demixed at temperatures in range from 723 to 773 K for times up to 20 h. It is found that increasing time and temperature lead to characteristic changes in the size distribution of boron trioxide drops in the lead-rich glassy matrix (<80.7 mol. % B2O3). The increase of the mean drop size with annealing time followed the cube root time dependence of diffusion controlled coarsening. The diffusivity of the coarsening process was determined using liquid-liquid interfacial energy associated with drop deformation in glass specimens subjected to uniaxial compression. Diffusion coefficients of coarsening were found to match with those of (207)Pb and (18)O tracer ions in the lead borate system but differ up to four orders of magnitude from the Eyring diffusivity and by a factor of ≈7 from the activation energy of viscous flow. The results indicate that coarsening in demixed lead borate melts is most likely controlled by the short range dynamics of the interaction between lead cations and BO4 units, which are decoupled from the time scales of cooperative rearrangements of the glassy network at T < 1.1 Tg.

Wearable sensor systems: the challenges.

Given the soaring costs associated with the treatment of ever more prevalent chronic disease, it is widely agreed that a revolution is required in health care provision. It is often thought that the necessary technology already exists for the home-based monitoring of such patients and that it is other factors which are holding back the more widespread clinical uptake of these new tools. The authors suggest that the necessary sensor-related technologies are often not as advanced as may first appear; certainly they are generally not adequate for the robust, long-term monitoring of patients under real-life conditions. An additional problem is the evident efforts to apply a given sensor and related technology platform to any and all monitoring scenarios without sufficient consideration of patient needs and the clinical requirements. The authors review the key sensing platforms and suggest the applications for which they are best suited.

Thermal parameters measurement on fire fighter: improvement of the monitoring system.

Real time monitoring of the thermal parameters on firefighter when operating is one of the ProeTEX project goals. The newly developed equipments in the framework of this project, integrate one temperature sensor and one heat flux sensor in the rescuer's outer garment. The environment in which firefighters operate is dangerous and the thermal risks can occur everywhere. Consequently the heat flux is so not necessarily symmetrical. To improve the thermally at risk situation detection, a modified platinum sensors array was integrated in the jacket in order to monitor simultaneously heat flux and temperature surrounding the rescuer. The sensors were placed in the most exposed area (shoulders and chest) to monitor thermal parameter in different directions. The heat flux is calculated from the temperature difference. This sensors array enables the detection of temperature increases and heat flux even when the heat source is localized on one side.

Thermal parameters measurement on fire fighter during intense fire exposition.

To improve rescuer safety, coordination and efficiency, the European program ProeTEX aims at developing new equipment for the intervention staff. This equipment is based on micro and nanotechnologies and consisted of smart textile integrated sensor to monitor physiological parameters, environment of the rescuer but also acquisition module and communication module. Thermal parameters are of primer interest. Internal temperature, external temperature and heat flux are relevant parameters to prevent heat stroke in fire fighter when exposed to intense fire. These parameters are recorded during fire exposition and highlight, on one hand, that the outer garment of fire fighters' equipment insulates the fire fighter from the external environment, and on the other hand, that the thermal monitoring is relevant.

Autonomic nervous system and subjective ratings of strain in air-traffic control.

The paper is aimed at studying the perceived strain in professional air-traffic controllers both through self-evaluation and physiological indicators from the autonomic nervous system (ANS). The number of aircraft to be monitored was the main independent variable and could evolve at random within 1 and 10. Five ANS variables were recorded continuously in 25 participants while they handled real traffic: skin potential, skin conductance, skin blood flow, skin temperature and instantaneous heart rate. The tonic level of each physiological variable was averaged to match the times spent monitoring a constant number of aircraft. After the session, participants reacted in compliance with the NASA-TLX rating scale. Subjective ratings and physiological values were closely correlated to the number of aircraft, especially when data were standardized thus reducing inter-subjects differences in baseline levels. Results provide objective information to prevent air-traffic controllers from overloaded situations as well as to improve passengers' safety.

Autonomic nervous system responses to sweet taste: evidence for habituation rather than pleasure.

Previous recordings of the variations of autonomic nervous system (ANS) parameters associated with each primary taste (sweet, salty, sour and bitter) showed that sweet taste induced very weak ANS responses, in the same range or weaker than responses evoked by mineral water. The purpose of this study was then to determine whether this weak ANS activation reflects the pleasant hedonic valence of sweet or the habituation of the organism to this innate-accepted taste. Twenty healthy volunteer subjects (8 males and 12 females, mean age=22.85 years) participated in the experiment. Taste stimuli were a solution of 0.3 M sucrose and three sweet flavours (orange juice, coke, lemonade) as "pleasant" sweet stimuli, and a solution of 0.15 M NaCl as an "unpleasant" stimulus. "Evian" mineral water served as the diluent and as a neutral stimulus. Throughout the test, five ANS parameters (skin potential and skin resistance, skin blood flow and skin temperature, instantaneous heart rate) were simultaneously and continuously recorded. After they had tasted each solution, subjects filled out a questionnaire in which they had to evaluate the hedonic dimension and the sweet intensity of each gustative stimulus. The lack of correlation between the mean hedonic scores associated with the four sweet stimuli and the mean values of the autonomic parameter variations tends to indicate that the weak ANS responses induced by the sweet gustative stimuli rather reflect the habituation of the organism to sweet taste than a gradation in sensory pleasure.

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 driver's mental state. Therefore, most methods based on physiological signals measurements have been improved on driving simulators or in experimental laboratories under carefully controlled conditions and rigorous protocols. To study driver's behavior in actual conditions, we have developed an in-vehicle system which could record contextual driving information, drivers' actions and physiological signals related to them. Recordings from the driver and the vehicle may give valuable information for a close estimation of driver's functional state, its evolution across time and thus a better understanding of driver's behavior. This system provides specific patterns related to the driver's functional state, according to the driving context. This paper is aimed to present the design and implementation of this system, well adapted to ergonomics.

MAPI: active interface pressure sensor integrated into a seat.

The purpose of MAPI project is to propose a method for interface pressure measurement. This method must be exact, easy to build, low cost, and must take into consideration viscoelastic characteristics of the skin and of human morphology. The main areas of the project is related to ergonomics of seating surfaces and prevention of pressure ulcers. An additional stage was performed by developing an electro-pneumatic interface pressure sensor directly integrated into a seat. The sensor is easy to use and presents acceptable characteristics. The average error is 2.58%, and the standard deviation is 1.66 mmHg. Spatial resolution is 3 cm. This first prototype will be improved, with better spatial resolution, and used for different pressure ulcer study and prevention tests.

New methodology for preventing pressure ulcers using actimetry and autonomous nervous system recording.

Pressure ulcers constitute an important health problem. They affect lots of people with mobility disorder and they are difficult to detect and prevent because the damage begins on the muscle. This paper proposes a new approach to study pressure ulcers. We aim at developing a methodology to analyse the probability for a patient to develop a pressure ulcer, and that can detect risky situation. The idea is to relate the mobility disorder to autonomic nervous system (ANS) trouble. More precisely, the evaluation of the consequence of the discomfort on the ANS (stress induced by discomfort) can be relevant for the early detection of the pressure ulcer. Mobility is evaluated through movement measurement. This evaluation, at the interface between soft living tissues and any support has to consider the specificity of the human environment. Soft living tissues have non-linear mechanical properties making conventional rigid sensors non suitable for interface parameters measurement. A new actimeter system has been designed in order to study movements of the human body whatever its support while seating. The device is based on elementary active cells. The number of pressure cells can be easily adapted to the application. The spatial resolution is about 4 cm(2). In this paper, we compare activity measurement of a seated subject with his autonomic nervous system activity, recorded by E.motion device. It has been developed in order to record six parameters: skin potential, skin resistance, skin temperature, skin blood rate, instantaneous cardiac frequency and instantaneous respiratory frequency. The design, instrumentation, and first results are presented.

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.

Interface pressure monitoring for a secured instrumented childbirth.

Complications in forceps deliveries are rare but their consequences might be dramatics. This situation could be avoided if the obstetrician knows the information concerning symmetry of the obstetrical forceps position on the fetal head and the related interface pressure. Indeed, forceps delivery is an emergency gesture which is normally not expected. Our purpose is to determinate relevant parameters for a fast decision-making without any danger for the fetus. We have developed a new interface pressure measurement system in order to study pressure distribution of human body whatever its support (forceps, chair, bed...). This method has been adapted to measure the interface pressure between the fetal head and the forceps. This new system also provides information of forceps position symmetries. The aims of this system are: first, to prevent instrumented delivery accidents. Secondly, to provide a safe training of forceps technique. This paper presents results about experiments performed on phantoms of fetal head. Different forceps positions on phantom have been tested according to the classification of forceps application as per A.C.O.G 1981 (revised in 1991). These experiments have lead to the definition of relevant parameters in order to help the physician to validate the forceps positions before extraction.

A non invasive wearable sensor for the measurement of brain temperature.

As the thermoregulation centres are deep in the brain, the cerebral temperature is one of the most important markers of fever, circadian rhythms physical and mental activities. However due to a lack of accessibility, the brain temperature is not easily measured. The axillary, buccal, tympanic and rectal temperatures do not reflect exactly the cerebral temperature. Nevertheless the rectal temperature is used as probably the most reliable indicator of the core body temperature. The brain temperature can be measured using NMR spectroscopy, microwave radiometry, near infrared spectroscopy, ultra-sound thermometry. However none of those methods are amenable to long term ambulatory use outside of the laboratory or of the hospital during normal daily activities, sport, etc. The brain core temperature "BCT" sensor, developed by the Biomedical Microsensors dpt of LPM at INSA-Lyon is a flexible active sensor using "zero-heat-flow" principle. The sensor has been used for experimental measurement: brain temperature during mental activity, and in hospital for the study of circadian rhythms. The results are in agreement with the measurement by the rectal probe. There are 2 versions of this sensor: a non ambulatory for the use in hospitals, and an ambulatory version using teletransmission. We are working for improving the autonomy of the ambulatory version up to several days. This wearable biomedical sensor (WBS) can be used for circadian assessment for chronobiology studies and in medical therapies.

[Obstetrical forceps: yesterday, today and tomorrow. Toward a new classification of obstetrical forceps]. / Les forceps hier, aujourd'hui et demain. Une nouvelle classification des forceps.

OBJECTIVE: Obstetrical forceps are used worldwide since more than 400 years. In 2003 forceps deliveries accounted for 6.3% of all deliveries of the AURORE Grand-Lyon perinatal network. Although more than 400 different forceps have been described, obstetrics handbooks neither describe experimental forceps nor provide any chapter dedicated to instrumental delivery training. Our aim was to provide junior obstetricians with information that will allow them to select the best instrument and to let them know about experimental as well as pedagogic forceps. PATIENTS AND METHODS: International literature review using the terms "forceps" and "delivery" and a four year experimental work involving a close collaboration between obstetricians and biomechanics of the INSA engineering school. RESULTS: Two instruments are presented as well as a new forceps classification. DISCUSSION AND CONCLUSION: This classification distinguishes between three types of forceps: operational forceps designed to delivers neonates, experimental forceps designed to study biomechanics and training forceps designed for resident training. For the first time the classic blind forceps procedure is transformed in a full screen real time procedure.

Autonomic nervous system activity during actual and mentally simulated preparation for movement.

The aim of this study was to compare actual versus mentally simulated preparation for a complex motor skill. Two behavioral periods are observed during weightlifting: (i) an initial phase in which the subject standing behind the bar is thought to focus his attention on forthcoming execution and (ii) a second phase between hands/bar contact and execution during which the subject is thought to increase activation. Such mental processes accompanying behavioral sequences are correlated with autonomic nervous system activity, phasic responses corresponding to allocation of attentional resources, and tonic variations related to increasing general activation. To study mental processes during preparation for action, 12 subjects performed actual and imagined preparation phases of execution. Six autonomic variables were measured continuously. Skin potential (chi2 = 0.16), skin temperature amplitude (Z = -0.66) and duration (Z = -1.78), skin blood flow amplitude (Z = -0.56) and duration (Z = -1.51), respiratory frequency amplitude (Z = -0.14) and duration (Z = -0.13), and duration of heart rate response (Z = -1.25) were shown to be comparable (p > .05), whatever the modality of preparation. However, during mentally simulated preparation, skin resistance response was shorter than in actual preparation (Z = -2.12, p < .05), thus attesting to a weaker load, whereas lower decrease in heart rate was elicited (Z = -1.96, p < .05). This may be explained by this particular experimental condition because mental preparation would not lead to actual action. Such autonomic variables could be used as feedback to improve performance.

Physiological and behavioral evaluation of mental load in shared attention tasks.

Hand-held phone use is prohibited by French law to prevent any motor interference with driving. If free-hands kit remains tolerated, its true impact (cognitive interference) is not already clearly determined. This experiment was aimed to study the effect of three communication tasks on driver's behavior: listening to the radio, discussing with a passenger and holding a hands-free phone conversation. Performance was assessed through reaction time (RT) to visual stimuli when driving on a private closed circuit. Drivers were requested to leave their foot from the accelerator pedal when orange lights, placed on the dashboard, switched on. This stimulus was triggered while subjects performed both driving and one of the three additional tasks. Skin resistance level (SRL) and instantaneous heart rate (IHR) were continuously recorded as indices of arousal. Rest and driving were taken as reference. Phoning while driving elicited the highest RT. SRL showed 3 levels of arousal, from the lowest to the highest: rest, driving and the dual task condition (driving + communication). Thus, arousal remained constant whatever the additional task although IHR showed that arousal was higher when phoning than when listening to the radio. Thus, managing two tasks simultanously elicited an increase in subjects' arousal whereas RT increased selectively as a function of the secondary task requirements.

FOR SAFE: instrumented and secured obstetrical forceps.

Operative vaginal deliveries represent a significant amount of vaginal deliveries. Operative delivery involves either forceps either vacuum extraction. Complications are frequent but rarely severe (cutaneaous lesions, facial palsy...). However, it is essential to limit these complications by helping the obstetrician to position his extraction instrument. It is the aim of the FOR SAFE device: provide a new instrumented forceps which performs the interface pressure measurement between the fetal head and the shanks of the forceps. Interface pressure evaluation requires interaction between the living tissue and the sensor, just like a man needs to touch an object with its fingertip to evaluate its compliance. The design of the sensor is "bio inspired". The sensor interacts with the matter, without modifying phenomenon to be measured.

Reversible meiotic abnormalities in azoospermic men with bilateral varicocele after microsurgical correction.

Because of a possible relationship between microenvironmental disturbances and meiotic abnormalities and of a straight relationship between lower-quality semen in patient carrying a varicocele and first meiotic non-disjunction, bilateral bipolar testicular biopsies are realized according the thermic differential gradient described in varicocele. Systematic meiotic studies of multiple testicular biopsies from 65 azoospermic men with bilateral varicocele were done in a multi-centric study on microsurgical correction of bilateral varicocele with microthermic intra-operative evaluation using minimally invasive thermal microsensors (Betatherm 10K3MCD2). In the present study abnormal temperature raising, histomorphometric abnormalities (spermatocyte arrest) and meiotic abnormalities (class IIC) are strongly correlated. In the ten patients submitted to another testicular biopsy procedure six months after surgery for TESE, normal thermal differential is registered and no meiotic abnormalities recurrences are found.

VTAMN--a smart clothe for ambulatory remote monitoring of physiological parameters and activity.

The prototype of a communicating underclothe for medical remote monitoring was realized. It delivers physiological information on the subject (Cardiac Frequency, Breathing Frequency, surface and mid-temperature) as well as the environment and activity parameters (ambient temperature, fall detection). It also enables the automatic data transfer on event, with the localization of the subject.

Wrist ambulatory monitoring system and smart glove for real time emotional, sensorial and physiological analysis.

Improvement of the quality and efficiency of the quality of health in medicine, at home and in hospital becomes more and more important Designed to be user-friendly, smart clothes and gloves fit well for such a citizen use and health monitoring. Analysis of the autonomic nervous system using non-invasive sensors provides information for the emotional, sensorial, cognitive and physiological analysis. MARSIAN (modular autonomous recorder system for the measurement of autonomic nervous system) is a wrist ambulatory monitoring and recording system with a smart glove with sensors for the detection of the activity of the autonomic nervous system. It is composed of a "smart tee shirt", a "smart glove", a wrist device and PC which records data. The smart glove is one of the key point of MARSIAN. Complex movements, complex geometry, sensation make smart glove designing a challenge. MARSIAN has a large field of applications and researches (vigilance, behaviour, sensorial analysis, thermal environment for human, cognition science, sport, etc...) in various fields like neurophysiology, affective computing and health monitoring.