Jeroen Bergmann

Body-Worn Sensor Design: What Do Patients and Clinicians Want?

User preferences need to be taken into account in order to be able to design devices that will gain acceptance both in a clinical and home setting. Sensor systems become redundant if patients or clinicians do not want to work with them. The aim of this systematic review was to determine both patients’ and clinicians’ preferences for non-invasive body-worn sensor systems. A search for relevant articles and conference proceedings was performed using MEDLINE, EMBASE, Current Contents Connect, and EEEI explore. In total 843 papers were identified of which only 11 studies were deemed suitable for inclusion. A range of different clinically relevant user groups were included. The key user preferences were that a body-worn sensor system should be compact, embedded and simple to operate and maintain. It also should not affect daily behavior nor seek to directly replace a health care professional. It became apparent that despite the importance of user preferences, they are rarely considered and as such there is a lack of high-quality studies in this area. We therefore would like to encourage researchers to focus on the implications of user preferences when designing wearable sensor systems.

The Effect of Coil Type and Navigation on the Reliability of Transcranial Magnetic Stimulation

The objective of this study was to investigate reliability of transcranial magnetic stimulation (TMS) parameters for three coil systems; hand-held circular and figure-of-eight and navigated figure-of-eight coils. Stimulus response curves, intracortical inhibition (SICI) and facilitation (ICF) were studied in the right first dorsal interosseus muscle of 10 healthy adults. Each coil system was tested twice per subject. Navigation was conducted by a custom built system. Cortical excitability showed moderate-to-good reliability for the hand-held and navigated figure-of-eight coils (Intraclass correlation coefficients (ICCs) 0.55-0.89). The circular coil showed poor reliability for motor evoked potential (MEP) amplitude at 120% resting motor threshold (RMT; MEP<;sub>;120<;/sub>;) and MEP sum (ICCs 0.09 & 0.48). Reliability for SICI was good for all coil systems when an outlier was removed (ICCs 0.87-0.93), but poor for ICF (ICCs <; 0.3). The circular coil had a higher MEP<;sub>;120<;/sub>; than the navigated figure-of-eight coil (p = 0.004). Figure-of-eight coils can be used confidently to investigate cortical excitability over time. ICF should be interpreted with caution. The navigation device frees the experimenter and enables tracking of the position of the coil and subject. The results help guide the choice of coil system for longitudinal measurements of motor cortex function.

Wearable and implantable sensors: the patient's perspective.

There has been a rising interest in wearable and implantable biomedical sensors over the last decade. However, many technologies have not been integrated into clinical care, due to a limited understanding of user-centered design issues. Little information is available about these issues and there is a need to adopt more rigorous evidence standards for design features to allow important medical sensors to progress quicker into clinical care. Current trends in patient preferences need to be incorporated at an early stage into the design process of prospective clinical sensors. The first comprehensive patient data set, discussing mobile biomedical sensor technology, is presented in this paper. The study population mainly consisted of individuals suffering from arthritis. It was found that sensor systems needed to be small, discreet, unobtrusive and preferably incorporated into everyday objects. The upper extremity was seen as the favored position on the body for placement, while invasive placement yielded high levels of acceptance. Under these conditions most users were willing to wear the body-worn sensor for more than 20 h a day. This study is a first step to generate research based user-orientated design criteria’s for biomedical sensors.

The gait of patients with one resurfacing and one replacement hip: a single blinded controlled study

PurposesPost arthroplasty gait analysis has up till now been performed on subjects walking slowly on flat ground rather than challenging them at faster speeds or walking uphill. We therefore asked: (1) Is there a measurable difference in the performance of hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) limbs at patients’ self-determined fastest walking speeds and steepest inclines? and (2) Is there a relationship between the observed differences between the gait of HRA and THA implanted limbs and patient walking speeds and inclines.MethodsIn an ethically approved study we recruited patients with bilateral hip arthroplasties: one HRA and one THA. Nine subjects were assessed using an instrumented treadmill at a range of speeds and inclines by a blinded observer. The ground reaction forces of subjects were recorded and an age, sex and BMI matched control group was used for comparison.ResultsIncreasing walking speed correlated strongly with between leg differences in weight acceptance (ru2009=u20090.9, pu2009=u20090.000) and push-off force (ru2009=u20090.79, pu2009=u20090.002). HRA implanted limbs accepted significantly more weight at top walking speeds (1208xa0Nu2009±u2009320 versus 1279xa0Nu2009±u2009370, pu2009=u20090.026) and pushed off with greater force when walking uphill (818xa0Nu2009±u2009163 versus 855u2009±u2009166, pu2009=u20090.012). HRA limbs more closely approximated to the gait of the normal control group.ConclusionsArthroplasty implants do have an impact on the gait characteristics of patients. Differences in gait are more likely to be evident when assessment is made at fast speeds and walking uphill. This study suggests that HRA may enable a more normal gait.

An Attachable Clothing Sensor System for Measuring Knee Joint Angles

Flexible sensors that can be integrated into clothing to measure everyday functional performance is an emerging concept. It aims to improve the patients quality of life by obtaining rich, real-life data sets. One clinical area of interest is the use of these sensors to accurately measure knee motion in, e.g., osteoarthritic patients. Currently, various methods are used to formally calculate joint motion outside of the laboratory and they include electrogoniometers and inertial measurement units. The use of these technologies, however, tends to be restricted, since they are often bulky and obtrusive. This directly influences their clinical utility, as patients and clinicians can be reluctant to adopt them. The goal of this paper is to present the development process of a patient centered, clinically driven design for an attachable clothing sensor (ACS) system that can be used to assess knee motion. A pilot study using 10 volunteers was conducted to determine the relationship between the ACS system and a gold standard apparatus. The comparison yielded an average root mean square error of ~ 1°, a mean absolute error of ~ 3°, and coefficient of determination above (R2) 0.99 between the two systems. These initial results show potential of the ACS in terms of unobtrusive long-term monitoring.

Frequency analysis of wireless accelerometer and EMG sensors data: Towards discrimination of normal and asymmetric walking pattern

This preliminary study reports on the combined use of wireless accelerometers and wireless EMG sensors for monitoring walking patterns. The sensor data was analyzed in frequency domain through FFT, PSD and time-frequency spectrogram analysis. Accelerometer spectra was found to shift towards lower frequencies (<;3 Hz) while EMG spectra of selected muscles shifted towards higher frequencies (>;50 Hz) during asymmetric walking. Median frequency was used to quantify the spectral shifts. The combined wireless accelerometer/EMG system showed potential for discrimination between the normal and asymmetric walking.

Exploring the use of sensors to measure behavioral interactions: an experimental evaluation of using hand trajectories.

Humans appear to be sensitive to relative small changes in their surroundings. These changes are often initially perceived as irrelevant, but they can cause significant changes in behavior. However, how exactly people’s behavior changes is often hard to quantify. A reliable and valid tool is needed in order to address such a question, ideally measuring an important point of interaction, such as the hand. Wearable-body-sensor systems can be used to obtain valuable, behavioral information. These systems are particularly useful for assessing functional interactions that occur between the endpoints of the upper limbs and our surroundings. A new method is explored that consists of computing hand position using a wearable sensor system and validating it against a gold standard reference measurement (optical tracking device). Initial outcomes related well to the gold standard measurements (ru200a=u200a0.81) showing an acceptable average root mean square error of 0.09 meters. Subsequently, the use of this approach was further investigated by measuring differences in motor behavior, in response to a changing environment. Three subjects were asked to perform a water pouring task with three slightly different containers. Wavelet analysis was introduced to assess how motor consistency was affected by these small environmental changes. Results showed that the behavioral motor adjustments to a variable environment could be assessed by applying wavelet coherence techniques. Applying these procedures in everyday life, combined with correct research methodologies, can assist in quantifying how environmental changes can cause alterations in our motor behavior.

Using a body sensor network to measure the effect of fatigue on stair climbing performance

In terms of self-rated health, the most important activities of daily living are those involving mobility. Of these activities stair climbing is regarded as the most strenuous. A loss of stair climbing ability with age is normally associated with a loss of muscle strength and power, while other factors that influence muscle function, such as fatigue, are often not taken into account. So far no research has been published on how long-lasting fatigue affects activities of daily living, despite the fact that it has been repeatedly proven, in laboratory settings, to influence muscle force production over long periods of time. Technological advances in body sensor networks (BSNs) now provide a method to measure performance during complex real-life situations. In this study the use of a BSN was explored to investigate the effects of long-lasting fatigue on stair climbing performance in 20 healthy adults. Stair climbing performance was measured before and after a fatiguing protocol using a BSN. Performance was defined by temporal and spatial parameters. Long-lasting fatigue was successfully induced in all participants using an exercise protocol. The BSN showed that post-exercise fatigue did not influence stair climbing times (p > 0.2) and no meaningful changes in joint angles were found. No effect on overall stair climbing performance was found, despite a clear presence of long-lasting fatigue. This study shows that physiological paradigms can be further explored using BSNs. Ecological validity of lab-based measurements can be increased by combining them with BSNs.

Clinical efficacy and effectiveness of 3D printing: a systematic review

Objective To evaluate the clinical efficacy and effectiveness of using 3D printing to develop medical devices across all medical fields. Design Systematic review compliant with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Data sources PubMed, Web of Science, OVID, IEEE Xplore and Google Scholar. Methods A double-blinded review method was used to select all abstracts up to January 2017 that reported on clinical trials of a three-dimensional (3D)-printed medical device. The studies were ranked according to their level of evidence, divided into medical fields based on the International Classification of Diseases chapter divisions and categorised into whether they were used for preoperative planning, aiding surgery or therapy. The Downs and Black Quality Index critical appraisal tool was used to assess the quality of reporting, external validity, risk of bias, risk of confounding and power of each study. Results Of the 3084 abstracts screened, 350 studies met the inclusion criteria. Oral and maxillofacial surgery contained 58.3% of studies, and 23.7% covered the musculoskeletal system. Only 21 studies were randomised controlled trials (RCTs), and all fitted within these two fields. The majority of RCTs were 3D-printed anatomical models for preoperative planning and guides for aiding surgery. The main benefits of these devices were decreased surgical operation times and increased surgical accuracy. Conclusions All medical fields that assessed 3D-printed devices concluded that they were clinically effective. The fields that most rigorously assessed 3D-printed devices were oral and maxillofacial surgery and the musculoskeletal system, both of which concluded that the 3D-printed devices outperformed their conventional comparators. However, the efficacy and effectiveness of 3D-printed devices remain undetermined for the majority of medical fields. 3D-printed devices can play an important role in healthcare, but more rigorous and long-term assessments are needed to determine if 3D-printed devices are clinically relevant before they become part of standard clinical practice.

F-dynamics: Automated quantification of dendrite filopodia dynamics in living neurons

BACKGROUNDnDendritic filopodia are highly motile and flexible protrusions that explore the surroundings in search for an appropriate presynaptic partner. Dendritic filopodia morphologically and functionally transform into postsynaptic dendritic spines, once the appropriate partner has been chosen. Therefore, proper formation of synapses depends on the dynamics of dendritic filopodia and spines. Thus, a rigorous assessment of dendrite filopodia behavior could be informative in providing a link between filopodia dynamics and synaptic development.nnnNEW METHODnIn this paper, a tool for automated tracking of filopodia dynamics, the Filopodia-dynamics program (F-dynamics), will be described, tested and applied. The aim of this study is to validate the accuracy and reliability of F-dynamics and to test the program in live neurons.nnnRESULTSnWe demonstrate that filopodia dynamics can be reliably and accurately quantified using the F-dynamics program. In the present study, this program was used to successfully show that lithium treatment increases filopodia motility.nnnCOMPARISON WITH EXCITING METHODSnF-dynamics is the first analysis program that is able to determine dendritic filopodia dynamics automatically across both the longitudinal and lateral dimensions.nnnCONCLUSIONnOur data suggests that this analysis method can be used to differentiate between different experimental conditions and illustrates the potential of the program to measure pharmaceutical or genetic effects on filopodia dynamics.