Ink-based textile electrodes for wearable functional electrical stimulation: A proof-of-concept study to evaluate comfort and efficacy.

BACKGROUND: Functional Electrical Stimulation (FES) represents a promising technique for promoting functional recovery in individuals with neuromuscular diseases. Traditionally, current pulses are delivered through self-adhesive hydrogel Ag/AgCl electrodes, which allow a good contact with the skin, are easy-to-use and have a moderate cost. However, skin adherence decreases after a few uses and skin irritations can originate. Recently, textile electrodes have become an attractive alternative as they assure increased durability, easy integration into clothes and can be conveniently cleaned, improving the wearability of FES. However, as various manufacture processes were attempted, their clear validation is lacking. This proof-of-concept study proposes a novel set of ink-based printed textile electrodes and compares them to adhesive hydrogel electrodes in terms of impedance, stimulation performance and perceived comfort. METHODS: The skin-electrode impedance was evaluated for both types of electrodes under different conditions. These electrodes were then used to deliver FES to the Rectus Femoris of 14 healthy subjects to induce its contraction in both isometric and dynamic conditions. This allowed to compare the two types of electrodes in terms of sensory, motor, maximum and pain thresholds, FES-induced range of motion during dynamic tests, FES-induced torque during isometric tests and perceived stimulation comfort. RESULTS: No statistically significant differences were found both in terms of stimulation performance (Wilcoxon test) and comfort (Generalized Linear Mixed Model). CONCLUSION: The results showed that the proposed ink-based printed textile electrodes can be effectively used as alternative to hydrogel ones. Further experiments are needed to evaluate their durability and their response to sterilizability and stretching tests.

Wearable textile based on silver plated knitted sensor for respiratory rate monitoring.

Wearable systems are gaining broad acceptance for monitoring physiological parameters in several medical applications. Among a number of approaches, smart textiles have attracted interest because they are comfortable and do not impair patients' movements. In this article, we aim at developing a smart textile for respiratory monitoring based on a piezoresistive sensing element. Firstly, the calibration curve of the system and its hysteresis have been investigated. Then, the proposed system has been assessed on 6 healthy subjects. The volunteers were invited to wear the system to monitor their breathing rate. The results of the calibration show a good mean sensitivity (i.e., approximately 0.11V·%-1); although the hysteresis is not negligible, the system can follow the cycles also at high rates (up to 36 cycle·min-1). The feasibility assessment on 6 volunteers (two trials for each one) shows that the proposed system can estimate with good accuracy the breathing rate. Indeed, the results obtained by the proposed system were compared with the ones collected with a spirometer, used as reference. Considering all the experiments, a mean percentage error was approximately 2%. In conclusion, the proposed system has several valuable features (e.g., the sensing element is lightweight, the sensitivity is high, and it is possible to develop comfortable smart textile); in addition, the promising performances considering both metrological properties and assessment on volunteers foster future tests focused on: i) the possibility of developing and system embedding several sensing elements, and ii) to develop a wireless acquisition system, to allow comfortable and long-term acquisition in both patients and during sport activities.

Cognitive ability assessment by brain-computer interface validation of a new assessment method for cognitive abilities.

Brain-Computer Interfaces (BCIs) are systems which can provide communication and environmental control to people with severe neuromuscular diseases. The current study proposes a new BCI-based method for psychometric assessment when traditional or computerized testing cannot be used owing to the subject's output impairment. This administration protocol was based on, and validated against, a widely used clinical test (Raven Colored Progressive Matrix) in order to verify whether BCI affects the brain in terms of cognitive resource with a misstatement result. The operating protocol was structured into two phases: phase 1 was aimed at configuring the BCI system on the subject's features and train him/her to use it; during phase 2 the BCI system was reconfigured and the test performed. A step-by-step checking procedure was adopted to verify progressive inclusion/exclusion criteria and the underpinning variables. The protocol was validated on 19 healthy subjects and the BCI-based administration was compared with a paper-based administration. The results obtained by both methods were correlated as known for traditional assessment of a similarly culture free and reasoning based test. Although our findings need to be validated on pathological participants, in our healthy population the BCI-based administration did not affect performance and added a further control of the response due to the several variables included and analyzed by the computerized task.

Functional evaluation and rehabilitation engineering.

Life is complex and all about movement, which allows us to interact with the environment and communicate with each other. The human nervous system is capable of performing a simultaneous and integrated control of 100-150 mechanical degrees of freedom of movement in the body via tensions generated by about 700 muscles. In its widest context, movement is carried out by a sensory motor system comprising multiple sensors (visual,auditory, and proprioceptive),multiple actuators (muscles acting on the skeletal system),and an intermediary processor that can be summarized as a multiple-input­multiple-output nonlinear dynamic time-varying control system. This grand control system is capable of responding with remarkable accuracy,speed, appropriateness,versatility, and adaptability to a wide spectrum of continuous and discrete stimuli and conditions and is certainly orders of magnitude more complex and sophisticated than the most advanced robotic systems currently available. In the last decades,a great deal of research has been carried out in the fields of functional evaluation of human performance and rehabilitation engineering. These fields combine knowledge, concepts, and methods from across many disciplines (e.g., biomechanics,neuroscience, and physiology), with the aim of developing apparatuses and methods fort he measurement and analysis of complex sensory motor performance and the ultimate goal of enhancing the execution of different tasks in both healthy people and persons with reduced capabilities from different causes (injury, disease, amputation,and neural degeneration).

Telefetalcare: a first prototype of a wearable fetal electrocardiograph.

Fetal heart rate monitoring is fundamental to infer information about fetal health state during pregnancy. The cardiotocography (CTG) is the most common antepartum monitoring technique. Abdominal ECG recording represents the most valuable alternative to cardiotocography, as it allows passive, non invasive and long term fetal monitoring. Unluckily fetal ECG has low SNR and needs to be extracted from abdominal recordings using ad hoc algorithms. This work describes a prototype of a wearable fetal ECG electrocardiograph. The system has flat band frequency response between 1-60 Hz and guarantees good signal quality. It was tested on pregnant women between the 30(th) and 34(th) gestational week. Several electrodes configurations were tested, in order to identify the best solution. Implementation of a simple algorithm for FECG extraction permitted the reliable detection of maternal and fetal QRS complexes. The system will allow continuative and deep screening of fetal heart rate, introducing the possibility of home fetal monitoring.

An automated method for relevant frequency bands identification based on genetic algorithms and dedicated to the Motor Imagery BCI protocol.

This paper presents an automated method for relevant frequency bands identification to be used in a left/right hand motor imagery based Brain Computer Interface system. The adopted optimization method aimed at maximizing the ratio between the mutual information and the error rate obtained using a Regularized Linear Discriminant Analysis (RLDA) based classifier and band-specific amplitude modulated envelopes as features. The search problem was handled by a genetic algorithm starting from an initial population determined on the basis of a-priori mu and beta relevant frequency bands identified by means of a standard power spectral density analysis between the idle and the left/right imagery data subset.

Behavioral and psychotic symptoms of dementia (BPSD) improvements in a special care unit: a factor analysis.

BPSD are very frequent, so that 90% of demented patients have at least one. BPSD are troublesome both for elders with dementia and for caregivers, fostering the institutionalization. Yet, BPSD may vary as long as the disease progresses, and may fluctuate in the short run, either spontaneously or by pharmacological as well as non-pharmacological interventions. The aim of the study was to investigate by factor analysis possible groupings among the modifications occurring in BPSD, during the stay in a special care unit (SCU). BPSD were rated through the neuropsychiatric inventory (NPI); frequency x severity scores were calculated for any single BPSD at entry and at discharge: the differences were analyzed using factor analysis. The sample comprised 214 demented persons, 65.4% females; of mean age 79.6 years; Overall entry score of NPI was 46.1+/-20.7; NPI overall mean difference at discharge=-30.4+/-20.3. BPSD factor analysis on frequency x severity crude baseline scores resulted in 4 groups: 1 (agitation+irritability+aberrant motor activity+disinhibition); 2 (delusions+hallucinations); 3 (anxiety+dysphoria); 4 (apathy+euphoria). When differences (discharge frequency x severity-entry frequency x severity) for each BPSD scores were factor analyzed, grouping was rather similar: (i) agitation+irritability; (ii) delusions+hallucinations; (iii) anxiety+dysphoria+aberrant motor activity; (iv) euphoria+disinhibition; (v) apathy. In our sample, BPSD improved during the stay in the SCU. These improvements followed trajectories that looked plausible and were consistent with baseline groupings, by factor analysis.

Functional assessment of the lumbar spine through the optoelectronic ZooMS system. Clinical application.

AIM: The radiographic method remains the main imaging technique for the physiological, anatomical and possibly pathological analysis of the spine thanks to its ease of use, precision and reliability. Despite this, the technique is inadequate for functional and dynamic studies. This paper aims to apply a dedicated noninvasive methodology based on optoelectronic techniques for the functional evaluation of the lumbar spine. METHODS: A reference data set for typical movements (i.e. flexion/extension, lateral bending, axial rotation) of the lumbar spine has been developed. Twenty healthy subjects have been recruited (10 males and 10 females) to create the databases of healthy subjects; one subject who suffers from lumbar spine diseases has been analyzed and his mobility has been compared to healthy subjects. RESULTS: Two databases have been created: in the former, the entire movement is normalized in time with respect to its duration; in the latter, all movements are classified in characteristic phases and each single phase is normalized to a defined duration. These databases include both the global movement of the lumbar tract of the spine and the movement of the single functional units (2 vertebrae, the intervertebral disk and the intervening surrounding soft tissues). Moreover, these databases are divided into male and female databases according to the natural differences in range of motion and pattern of movement. A clinical application for pathologic subjects is shown demonstrating the applicability and usability of this protocol. CONCLUSION: This method allows to assess both the quality and the quantity of lumbar spine movement (both global and metameric level) of the subject and to distinguish the patient from the healthy subject.

A four command BCI system based on the SSVEP protocol.

This paper discusses the development of a four command BCI system. This system is composed of a wearable electroencephalogram acquisition unit interfaced to a computer by a wireless Bluetooth (BT) connection. The implemented system relies on the steady-state visual evoked potential (SSVEP) protocol applied to a four selection system. In order to achieve the maximum reliability against false positives a five class classifier was used considering the idle state as an independent class. In order to maximize the usability of the system a two channel solution was tested and adopted. The BCI algorithm was based on a supervised multi-class classifier implemented by combining different binary regularized linear discriminant analysis (RLDA) classifiers. The biofeedback was evaluated by combining the resultant time signed distance with quality index related to the number of coherent identification obtained with the one-vs-all approach.

A wearable device for continuous monitoring of heart mechanical function based on impedance cardiography.

In this study we explored the possibility to realize a low power device for Cardiac Output continuous monitoring based on impedance cardiography technique. We assessed the possibility to develop a system able to record data allow an intra-subjective analysis based on the daily variations of this measure. The device was able to acquire and to send signals using a wireless Bluetooth transmission. The electronic circuit was designed in order to minimize power consumption, dimension and weight. The reported results were interesting for what concerns the power consumption and then noise level. In this way was obtained a wearable device that will permit to define specific clinical protocols based on continuous monitoring of the Cardiac Output signal.

Evaluation of head-to-trunk control in whiplash patients using digital CranioCorpoGraphy during a stepping test.

We used digital-CranioCorpoGraphy (dCCG) to document whiplash effects on head-on-trunk stabilization while subjects walked on the spot (Fukuda test). Twenty-five healthy subjects were compared with 33 whiplash patients. Whiplash patients were classified as chronic (more than 6 months after injury) and recent (less than 6 months after injury). Clear differences between healthy subjects and patients were seen and three different strategies were detected. Pattern A appeared similar to normals but quantitative analysis showed significant differences with paradoxical head over-stabilization (collar-effect); pattern B decreased head stability; pattern C decreased head stabilization with reduced displacements of the body. Due to the complexity of the data analyzed for each marker, a coefficient of performance (CP) was calculated to simplify the cut-off between normal and pathological tests. CP clearly identified an abnormal stepping pattern. Our findings indicate that firstly dCCG identified a specific vestibular task in whiplash patients, secondly whiplash did not always provoke vestibular involvement and thirdly dCCG could be a tool to discriminate patients with and without vestibular involvement after whiplash.

ZooMS: a non invasive analysis of global and metameric movement of the lumbar spine.

AIM: The assessment of spine mobility is an important parameter to define its functionality. In the last decades a lot of research has been carried out mainly through radiographic investigations; non invasive methods demonstrated not to be sufficiently accurate, not to allow free movement, not to provide metameric assessment and suitable for everyday clinical practice. The aim of this study is the development of a new experimental non invasive protocol, called Zoom on mobility of the spine (ZooMS) to assess the mobility of lumbar spine, from the 11th thoracic to the sacrum bone and the pelvis, with the possibility of identifying the metameric contribution of each rotation around all the axes correlated to the global movement. METHODS: We developed a dedicated non invasive methodology based on optoelectronic techniques for 3D target recording to be applied to the functional evaluation of the mobility of the lumbar spine in young healthy males. Ten subjects participated in the method validation, performing free rotations (flexion/extension, lateral bending and axial rotation) from standing to the maximum excursion and back. RESULTS: The comparison of the range of motion (RoM) with those presented in literature was satisfactory, although some differences were shown (above all in axial rotation, which however gives the minor contribution to the mobility of the lumbar spine). The validation of the protocol was successful in terms of intraoperator, interoperator and circadian remarking, the 3 factors eventually affecting its repeatability. CONCLUSION: The RoM of the whole lumbar spine and of each functional unit, together with the pattern of movement may so represent an innovative and important aspect in clinical applications.

Kinematics of head-trunk movements while entering and exiting a car.

The study of free and natural accessibility movements for a medium-sized car was carried out, recording the motor performances of ten participants by means of a motion analysis system. The experimental protocol used passive markers to implement a two-segment biomechanical model for the analysis of the head-trunk complex. The kinematic variables quantify the motor patterns, and showed specific features that can be related to the individual anthropometric characteristics and to the car geometry differences: tall participants used a neck flexion and a leftwards bending of the head, while short participants extended the neck and bent the head to the right. The different seat positions (short participants move forwards the seat) along with the principal need to avoid any body interference with the car, can explain the observed strategies. From the wider analysis of the movements in relation to the vehicle's features and to the anthropometric size of the participants, this approach could lead to an extension of the design criteria for those structural components of the car which have been demonstrated to significantly influence the human-machine interaction.

Cancer incidence in eighteen cities of the State of São Paulo, Brazil.

OBJECTIVE: As in Brazil cancer registries are mostly based on large cities, there are no estimates per state or per region and information on the disease incidence in the vast in-land areas is very scarce. An incidence survey was conducted in 18 major cities of the state of São Paulo, excluding the capital, aiming to collect information about cancer incidence in the state of São Paulo. METHODS: Of the 18 cities in state of São Paulo included in the survey, all had available resources for cancer management. Data from the year of 1991 were collected by the personnel of the Instituto Brasileiro de Geografia e Estatística (Brazilian Institute of Statistics), who were especially trained by the study coordinators at the Fundação Oncocentro de São Paulo (Cancer Center of São Paulo). The collected data were processed and analyzed at the Oncocentro. Data collection, processing, and analyses were performed according to the recommendations of the International Agency for Research on Cancer. RESULTS: Although some discrepancies were observed in cancer incidence rates between the cities, results obtained for all 18 cities combined were remarkably close to those recently found for the city of São Paulo in the year 1993. One remarkable finding was the relatively high cancer incidence rates in both sexes in the city of Santos. CONCLUSIONS: The very similar all-sites cancer incidence rates found in the year 1991, when compared to those for the city of São Paulo in the year 1993, are suggestive that all regions have common cancer-related factors. Nevertheless, other explanations, such as the inclusion in the study of prevalent cases, as well as of non-residents, may have occurred in both studies, biasing the results. There is a need of further studies to confirm the high cancer incidence in Santos.

Comparative biomechanical evaluation of different wheelchair seat cushions.

The aim of the present study was to perform a comparative biomechanical analysis of four antidecubitus wheelchair cushions. Thirty wheelchair users were considered divided into three groups: paraplegic subjects (with no cutaneous sensation), neurologic subjects (with intact cutaneous sensation), and elderly subjects. The biomechanical evaluation was performed using a piezoresistive sensor matrix system to quantify parameters referred to pressure distribution, seating surface and posture. Dedicated software was developed for the automatic elaboration of the raw data and the computation of the parameters of interest. Differences among cushion types and subject groups were analyzed. An analysis of time-transient behaviors was also performed. Results showed that no significant differences in pressure peak reduction were found among the four cushions. Moreover, no time-transient behavior was shown by any cushions. However, both the location of pressure peaks and posture were dependent on cushion types. Comparison of the three subject groups showed that elderly subjects had the highest mean pressure and the lowest contact surface, while paraplegics presented the highest pressure peaks. This procedure appears indicated for individualizing the prescription of a wheelchair cushion and even for customizing a cushion to induce a specific posture.

Quantitative analysis of neutral body posture in prolonged microgravity.

The experiment was performed during a 6-month space flight and focused on the quantitative three-dimensional description of the Neutral Body Posture (NBP) and of subjects' spine anthropometry in Erect Posture (EP). The NBP joint angles' configuration is described along the long-term microgravity exposure and compared with respect to previous in-flight collected data. Observed spinal length modification during EP in-flight is related to on-ground investigations focused on circadian anthropometrical fluctuations. The flattening of the spinal lumbar lordosis and thoracic kyphosis is also described. Even though only two subjects were studied, this analysis points out the maturity of the opto-electronic technology for the quantitative analysis of posture in microgravity and confirms the need of enriching the anthropometrical database of human postures in weightlessness for the design optimization of permanently inhabited space modules.

Changes in diastolic function and collagen content in normotensive and hypertensive rats with long-term streptozotocin-induced diabetes.

We investigated the relationship between left ventricular diastolic function and interstitial collagen content in the endocardium, mesocardium and epicardium of transverse sections of the heart, using an image analysis system in normotensive and hypertensive long-term streptozotocin (STZ) diabetic rats. STZ-induced diabetes was characterised by elevated blood glucose, polyuria, polydypsia and loss of body weight. In vivo systolic blood pressure was 165 +/- 4, 136 +/- 3 and 129 +/- 7 mmHg in hypertensive and normotensive diabetic rats and age-matched controls, respectively. Heart rate was significantly lower (P < 0.01) in diabetic rats (283 +/- 8 and 280 +/- 10 beats min-1 in normotensive and hypertensive rats, respectively) than controls (393 +/- 18 beats min-1). Pressure-volume (P-V) curves were studied in isolated Langendorff perfused hearts at rest and after 20 min global ischaemia and 30 min reperfusion 6 months after induction of diabetes. Left ventricular volumes were significantly smaller in diabetic rats than age-matched controls, but volumes normalised for heart weight were higher in normotensive (by 28%) and hypertensive (by 10%) diabetic rats. Slopes of end-diastolic P-V curves were similar between groups in basal conditions, but left ventricular systolic P-V curves were steeper in normotensive and flatter in hypertensive diabetic hearts. Post-ischaemic left ventricular end-diastolic pressure was significantly higher than the pre-ischaemic value at comparable increments of volume in each group. Collagen content significantly increased in the heart of rats with STZ-diabetes both in the free left ventricular wall and septum, and suggested this may play a role in the cardiac defects in contractility and relaxation in our experimental conditions. These results indicate that diabetes, irrespective of associated hypertension, can cause major changes in cardiac performance and susceptibility to ischaemia and reperfusion.

Quantitative analysis of motion control in long term microgravity.

In the frame of the 179-days EUROMIR '95 space mission, two in-flight experiments have foreseen quantitative three-dimensional human movement analysis in microgravity. For this aim, a space qualified opto-electronic motion analyser based on passive markers has been installed onboard the Russian Space Station MIR and 8 in flight sessions have been performed. Techhology and method for the collection of kinematics data are described, evaluating the accuracy in three-dimensional marker localisation. Results confirm the suitability of opto-electronic technology for quantitative human motion analysis on orbital modules and raise a set of "lessons learned", leading to the improvement of motion analyser performance with a contemporary swiftness of the on-board operations. Among the experimental program of T4, results of three voluntary posture perturbation protocols are described. The analysis suggests that a short term reinterpretation of proprioceptive information and re-calibration of sensorimotor mechanisms seem to end within the first weeks of flight, while a continuous long term adaptation process allows the refinement of motor performance, in the frame of never abandoned terrestrial strategies.

Densitometric quantification of neuronal viability by computerized image analysis.

A new method is presented for the quantification of cell viability based on densitometry with computerized image analysis. Neuronal cells were stained with crystal violet and densitometric analysis was performed with an IBAS 2.0 image analyzer (Kontron/ Zeiss), using specially implemented dedicated software which integrates the optical density of the culture in each well with the area covered by the stained cells. To test the reliability of the densitometric method cortical cells were plated at different concentrations (5 x 10(4)-10(6)/ml); the standard curve obtained by analysis of crystal violet staining showed a linear proportion between cell number and optical density signal. The validation and accuracy of the method were assessed and compared with other methods using rat cortical cells cultured in vitro for 10 days and exposed to kainic acid (250 microM) for 24 h. Neuronal viability was reduced by 40-50% and comparison with direct cell counting, MTT assay, and spectrophotometric analysis confirmed that the method is simple, quick, and reliable.