Non-invasive Physiological Monitoring Research Articles

Feather corticosterone is lower in translocated and historical populations of the endangered Laysan duck (Anas laysanensis).

Identifying reliable bioindicators of population status is a central goal of conservation physiology. Physiological stress measures are often used as metrics of individual health and can assist in managing endangered species if linked to fitness traits. We analysed feather corticosterone, a cumulative physiological stress metric, of individuals from historical, translocated, and source populations of an endangered endemic Hawaiian bird, the Laysan duck (Anas laysanensis). We hypothesized that feather corticosterone would reflect the improved reproduction and survival rates observed in populations translocated to Midway and Kure Atolls from Laysan Island. We also predicted less physiological stress in historical Laysan birds collected before ecological conditions deteriorated and the population bottleneck. All hypotheses were supported: we found lower feather corticosterone in the translocated populations and historical samples than in those from recent Laysan samples. This suggests that current Laysan birds are experiencing greater physiological stress than historical Laysan and recently translocated birds. Our initial analysis suggests that feather corticosterone may be an indicator of population status and could be used as a non-invasive physiological monitoring tool for this species with further validation. Furthermore, these preliminary results, combined with published demographic data, suggest that current Laysan conditions may not be optimal for this species.

Advancing Wearable Biosensors for Congenital Heart Disease: Patient and Clinician Perspectives: A Science Advisory From the American Heart Association.

Wearable biosensors (wearables) enable continual, noninvasive physiologic and behavioral monitoring at home for those with pediatric or congenital heart disease. Wearables allow patients to access their personal data and monitor their health. Despite substantial technologic advances in recent years, issues with hardware design, data analysis, and integration into the clinical workflow prevent wearables from reaching their potential in high-risk congenital heart disease populations. This science advisory reviews the use of wearables in patients with congenital heart disease, how to improve these technologies for clinicians and patients, and ethical and regulatory considerations. Challenges related to the use of wearables are common to every clinical setting, but specific topics for consideration in congenital heart disease are highlighted.

Opening the envelope: Efficient envelope-based PPG denoising algorithm

Photoplethysmography (PPG) signals obtained from the skin’s surface offer valuable insights into blood volume fluctuations. With the rising interest in continuous non-invasive physiological monitoring, PPG has garnered significant attention. However, PPG signals are often affected by various forms of noise, impeding reliable feature extraction. Robust data pre-processing approaches are vital for both retrospective and real-time analysis. Existing denoising methods, including recent machine learning techniques, often suffer from implementation challenges, computational inefficiency, and limited interpretability. Addressing this challenge, we propose a novel PPG denoising algorithm. The algorithm was evaluated using a dataset representing approximately 81,015.99 min or 1360.27 h of PPG data collected from 31 patients. The evaluation involved the calculation and analysis of five key metrics: Signal-to-Noise Ratio (SNR), Variance, Total Variation (TV), Shannon entropy, and Instances-per-second (IPS). Our results demonstrate a notable increase in SNR after denoising, indicating effective noise reduction while preserving signal content. Variance and TV values showed a reduction post-denoising, suggesting smoother and less variable signals, validating the noise suppression efficacy. Additionally, Shannon entropy exhibited a decrease after denoising, indicating successful noise reduction and enhanced signal regularity. The nonparametric Wilcoxon signed-rank test (a = 0.05) was employed to assess the statistical significance of the observed differences of these metrics before and after denoising. Furthermore, the computational speed analysis revealed the EPDA’s potential for efficient processing of large datasets and real-time applications. This comprehensive evaluation approach allows for a thorough understanding of the EPDA’s effectiveness in denoising PPG data, fostering advancements in non-invasive physiological monitoring and promoting the broader adoption of PPG-based healthcare technologies.

Microneedle Enabled Electrochemical Aptamer-Based Sensing: Real Time Measurements Using Stainless Steel Microneedles

Electrochemical aptamer-based (EAB) sensors are among the only generalizable sensing platforms that resist fouling enough to function directly in bodily fluids and in situ in the living body. Already, these sensors have enabled the real-time measurement of a range of small molecule targets in vivo, including pharmaceuticals and drugs of abuse. EAB sensors consist of an electrode-attached, redox reporter-labeled aptamer that binds to its target species. Target binding causes a shift in electron-transfer rate between the redox reporter and electrode surface, easily detected by a range of electrochemical techniques. Here, we explore the application of EAB sensors to minimally-invasive molecular monitoring. Specifically, we adapt the platform to a microneedle device format. Microneedles can provide direct access to the skin’s interstitial space – a bodily compartment that holds valuable information ranging from drug distribution and immune status. And because microneedles can penetrate into the top layers of the skin with minimal nerve endings, they can avoid eliciting notable pain responses.In this work, we demonstrate the substantial miniaturization of the sensing platform into electrodes thinner than a human hair, and then integrate them with ultra-fine, hollow microneedles. To ensure needle sterilizability and sharpness while avoiding complex fabrication, we utilize commercial off the shelf stainless steel microneedles. Using an EAB sensor responding to the high-toxicity small molecule drug, vancomycin, as a model system, we achieve quantitative measurements directly in body temperature, undiluted whole blood. Building on this milestone, we explore the application of the sensors when inserted into porcine skin. In porcine skin (a common proxy for human skin), we observe facile microneedle penetration and stable electrochemical signaling. Because of the individual addressability of the sensing electrodes and the generalizability of the aptamer platform, this technology is capable of multiplexed, simultaneous detection of many different molecular targets. Thus, microneedle-enabled aptamer-based sensors offer a promising route forward for non-invasive physiological monitoring – applicable to therapeutic drug monitoring, pain-free biomarker detection, and disease management.

Noninvasive Cardiac Output Monitoring (NICOM) in the Critically Ill Patient Undergoing Endotracheal Intubation: A Prospective Observational Study.

Background: Cardiovascular instability occurring during endotracheal intubation (ETI) in the critically ill is a commonly recognized phenomenon. However, this complication has not been evaluated in terms of the physiological cause (ie, decreased preload, contractility, or afterload) leading to the instability. Thus, the aim of the current investigation was to describe the hemodynamics occurring during ETI with noninvasive physiologic monitoring and to collect preliminary data on the hemodynamic effects of induction agents and positive pressure ventilation. Methods: A multicenter prospective study enrolling adult (≥18 years) critically ill patients undergoing ETI with noninvasive cardiac output monitoring in a medical/surgical intensive care unit from June 2018 to May 2019 was conducted. This study used the Cheetah Medical noninvasive cardiac output monitor to collect hemodynamic data during the peri-intubation period. Additional data collected included baseline characteristics such as illness severity, peri-intubation pharmacologic administration, and mechanical ventilation settings. Results: From the original 27 patients, only 19 (70%) patients had complete data and were included in the final analysis. Propofol was the most common sedative 8 (42%) followed by ketamine 6 (32%) and etomidate 5 (26%). Patients given propofol demonstrated a decrease in total peripheral resistance index (delta change [dynes × s/cm-5/m2]: -2.7 ± 778.2) but stabilization in cardiac index (delta change (L/min/m2]: 0.1 ± 1.5) while etomidate and ketamine demonstrated increases in total peripheral resistance index (etomidate delta change [dynes × s/cm-5/m2]: 302.1 ± 414.3; ketamine delta change [dynes × s/cm-5/m2]: 278.7 ± 418.9) but only etomidate resulted in a decrease in cardiac index (delta change [L/min/m2]: -0.3 ± 0.5). Positive pressure ventilation resulted in minimal changes to hemodynamics during ETI. Conclusions: The current study demonstrates that although propofol administration leads to a decrease in total peripheral resistance index, cardiac index is maintained while etomidate leads to a decrease in cardiac index with both etomidate and ketamine increasing total peripheral resistance index. These hemodynamic profiles are minimally affected by positive pressure ventilation. Study registration: ClinicalTrials.gov ID, NCT03525743.

Evaluation of jacketed telemetry in rats for cardiorespiratory phenotyping at exercise

The challenge of cardiorespiratory function through physical exercise is highly relevant to reveal pathological phenotypes, both in humans and animals, but available monitoring tools (implanted telemetry, metabolic chamber) remain challenging to use in the context of exercise. Recently, jacketed telemetry systems for small laboratory animals have been developed, allowing non-invasive physiological monitoring in various conditions. The aim of this work was to evaluate the feasibility, using this new technology, to monitor cardiorespiratory function during treadmill exercise in rats. The effects of a moderate-intensity treadmill exercise protocol were monitored using a non-invasive telemetric jacket on a group of untrained male wistar rats (N = 9, 9–10 weeks). This incremental protocol consisted in increase the speed level of 5 cm/sec every 2 minutes (Speed: from 10 to 35 cm/sec max). Heart rate (HR), respiratory rate (RespR) and activity level (AL) were monitored with a small electronic Bluetooth device (15 g) and analyzed during a control state (Baseline), the last 30 seconds of each speed level and at post-exercise recovery. The animals were equipped with the device and placed back in their home cage. After 25 minutes of stabilization, HR was 392 ± 36 bpm, RespR was 173 ± 53 brpm, and AL was 15 ± 12 mg. All animals successfully ran on the treadmill with the jacket to the maximum speed of 35 cm/sec. Exercise induced a significant physiological increase in HR (+26%, 104 ± 21 bpm, P < 0.01) and RespR (+73%, 126 ± 22 brpm, P < 0.01). In conclusion, this novel telemetry jacket can be used to monitor cardiorespiratory parameters adaptation during a standard forced exercise protocol. Jacketed telemetry provides a completely non-invasive way to study the phenotypes of animals avoiding any additional risk on fragile pathological models and meeting the regulatory 3Rs requirements. As illustrated phenotype characterization can be enriched with a monitoring of the animal in various situations (treadmill, home cage, but also metabolic or hypoxia cage, etc.…).

Detecting unique analyte-specific radio frequency spectral responses in liquid solutions -- implications for non-invasive physiologic monitoring

With rising healthcare costs and the rapid increase in remote physiologic monitoring and care delivery, there is increasing need for economical, accurate and non-invasive continuous measures of blood analytes. Based on radio-frequency identification (RFID), we have developed a novel electromagnetic platform technology (the Bio-RFID platform) to non-invasively penetrate inanimate surfaces, capture data from individual radio frequencies, and convert those data into physiologically meaningful information and insights. Here we describe ground-breaking proof-of-principle studies using Bio-RFID to accurately measure various concentrations of analytes in deionized water. The in vitro Bio-RFID platform consists of an acrylic cuvette in the shape of a 4 inch x 4 inch x 8 inch rectangular prism mounted on the Bio-RFID sensor. This apparatus is in turn mounted on a balance that allows the determination of the mass of the analyte being scanned to within 0.1g. The hardware scans through several thousand radio frequencies and sends the data to proprietary software running on a laptop computer. The software displays a spectral scan known as the Bio-RFID signature of the analyte and computes a similarity metric to compare different signatures.We tested the hypothesis that the Bio-RFID platform is able to precisely and non-invasively measure and identify a variety of analytes in vitro. For this assessment, varying solutions of 1) water in isopropyl alcohol; 2) salt in water; and 3) commercial bleach in water were tested, using a randomized double-blind trial design, as proxies for biochemical solutions in general. The Bio-RFID technology was able to detect concentrations of 2000 parts per million (ppm), with evidence suggesting the ability to detect considerably smaller concentration differences. The novel application of a Bio-RFID electromagnetic platform technology accurately detects, measures, and quantifies specific molecules in liquid. While these findings have in vitro commercial applications, these proof-of-principle studies provide strong support for the application of Bio-RFID technology for non-invasive bio-monitoring of physiologically and medically relevant analytes, such as alcohol and glucose, in the human body. These studies were funded by a grant from Know Labs to Mayo Clinic. PB and JHA are employed by Know Labs. VKS and Mayo Clinic acknowledge a financial interest in Know Labs. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Non-Invasive Physiological Monitoring for Physical Exertion and Fatigue Assessment in Military Personnel: A Systematic Review.

During operational activities, military personnel face extremely demanding circumstances, which when combined lead to severe fatigue, influencing both their well-being and performance. Physical exertion is the main condition leading to fatigue, and its continuous tracking would help prevent its effects. This review aimed to investigate the up-to-date progress on non-invasive physiological monitoring to evaluate situations of physical exertion as a pre-condition to fatigue in military populations, and determine the potential associations between physiological responses and fatigue, which can later result in decision-making indicators to prevent health-related consequences. Adhering to the PRISMA Statement, four databases (Scopus, Science Direct, Web of Science and PubMed) were used for a literature search based on combinations of keywords. The eligibility criteria focused on studies monitoring physiological variables through non-invasive objective measurements, with these measurements being developed in military field, combat, or training conditions. The review process led to the inclusion of 20 studies. The findings established the importance of multivariable assessments in a real-life context to accurately characterise the effects of military practices. A tendency for examining heart rate variables, thermal responses, and actigraphy measurements was also identified. The objectives and experimental protocols were diverse, but the effectiveness of non-invasive measurements in identifying the most fatigue-inducing periods was demonstrated. Nevertheless, no assessment system for standardised application was presented. Future work may include the development of assessment methods to translate physiological recordings into actionable information in real-time and mitigate the effects of fatigue on soldiers’ performance accurately.

INTEGRATED DESIGN OF PHYSIOLOGICAL MULTI-PARAMETER SENSORS ON A SMART GARMENT BY ULTRA-ELASTIC E-TEXTILE

The performance of electronic textile (E-textile)-based wearable sensors is largely determined by the wire and electrode contacting stability to the body, which is a multi-discipline challenge for smart garment designs. In this paper, an integrated design of wearable sensors on a smart garment is presented to concurrently measure the multi-channel electrocardiogram, respiration, and temperature signals in different regions of the body. Sensors in separative probe-controller schemes are introduced with full-textile designs of the electrodes and signal transmission wires. An ultra-elastic structure of E-textile wire is proposed with excellent electrical stability, high stretch ratio, and low tension under body dynamics. A complete garment integration solution of the probes, wires, and the sensors is presented. The design is evaluated by comparing the signal quality in static and moderate body movements, which shows clinical level comparable precision and stability. The proposed design may constitute a general solution of distributed noninvasive physiological multi-parameter detection and monitoring applications.

Development of GUI and Computational Algorithms for Real‐Time Physiological Autonomic Activity Tracking

Many modern diseases involve some form of autonomic disturbance/dysfunction, including diabetes, gastroparesis, and autoimmune inflammatory diseases. For some of these autonomic disruptive diseases, few studies have been able to quantify the autonomic dysfunction. Previous attempts usually resort to invasive means that carry additional risk to the patient. In addition, to properly stimulate the autonomic nervous system (ANS) artificially for treatment, quantification of dysfunction is needed for personalized medical treatment. This research has led to the development of a non-invasive, data-driven diagnostic tool that may be able to identify the type and degree of autonomic dysfunction by simply recording signals from the heart, stomach, and other vitals data, and feeding them into data-driven software. Here, BioCom Lab under Dr. Ward has developed a MATLAB-based research software that can filter and analyze several forms of biological signals for tailored viewing in a graphical user interface (GUI). The software includes several custom heart rate variability (HRV) analysis methods, several custom electrogastrogram analysis methods, and additional skin sympathetic nerve activity (SKNA) analysis implemented all into the GUI (see Fig. 1) for non-invasive physiological monitoring of potential autonomic activity. The software has been developed for real time and post hoc analysis of large data sets, enabling new insights into precise physiological monitoring by incorporating averaged data points with reference to an event or timepoint. For example, the GUI has been used on several large sets of patient data to discover the temporal interplay between autonomic activity and the cardiovascular and gastrointestinal systems where patients were monitored before and after water and Ensure drink consumption (Fig. 2). In this study's data, the GUI provided new visuals and insight from the capability to average 31 patients’ data with the same time base relative to the stimulus while also providing comparison capabilities between organ systems analysis. This research tool provides a new way to understand parasympathetic and sympathetic influence on organs, also enabling the ability to help identify timepoints of parasympathetic activity, as opposed to sympathetic activity, by monitoring organ activity. The research tool at hand has the potential to create better, less-invasive diagnostics that can help physicians to select the best course of treatment for their patients, as well as provide new analytical and visual tools for researchers to track effects on the ANS from both non-electrical and electrical stimuli.

Juvenile moose stress and nutrition dynamics related to winter ticks, landscape characteristics, climate-mediated factors and survival.

Moose populations in the northeastern United States have declined over the past 15years, primarily due to the impacts of winter ticks. Research efforts have focused on the effects of winter tick infestation on moose survival and reproduction, but stress and nutritional responses to ticks and other stressors remain understudied. We examined the influence of several environmental factors on moose calf stress hormone metabolite concentrations and nutritional restriction in Vermont, USA. We collected 407 fecal and 461 snow urine samples from 84 radio-collared moose calves in the winters of 2017-2019 (January-April) to measure fecal glucocorticoid metabolites (fGCM) concentrations and urea nitrogen:creatinine (UN:C) ratios. We used generalized mixed-effects models to evaluate the influence of individual condition, winter ticks, habitat, climate and human development on stress and nutrition in calf moose. We then used these physiological data to build generalized linear models to predict calf winter survival. Calf fGCM concentrations increased with nutritional restriction and snow depth during adult winter tick engorgement. Calf UN:C ratios increased in calves with lighter weights and higher tick loads in early winter. Calf UN:C ratios also increased in individuals with home ranges composed of little deciduous forests during adult winter tick engorgement. Our predictive models estimated that winter survival was negatively related to UN:C ratios and positively related to fGCM concentrations, particularly in early winter. By late March, as winter ticks are having their greatest toll and endogenous resources become depleted, we estimated a curvilinear relationship between fGCM concentrations and survival. Our results provide novel evidence linking moose calf stress and nutrition, a problematic parasite and challenging environment and winter survival. Our findings provide a baseline to support the development of non-invasive physiological monitoring for assessing environmental impacts on moose populations.

Automatic Detection of Learner Engagement Using Machine Learning and Wearable Sensors

Training can now be delivered on a large scale through mobile and web-based platforms in which the learner is often distanced from the instructor and their peers. In order to optimize learner engagement and maximize learning in these contexts, instructional content and strategies must be engaging. Key to the development and study of such content and strategies, and adaptation of instructional techniques when learners become disengaged, is the ability to objectively assess engagement in real-time. Previous self-reported metrics, or expensive EEG-based engagement measures are not appropriate for large-scale platforms due to their complexity and cost. Here we describe the development and testing of a measurement and classification technique that utilizes non-invasive physiological and behavioral monitoring technology to directly assess engagement in classroom, simulation, and live training environments. An experimental study was conducted with 45 students and first responders in a unmanned aircraft systems (UAS) training program to assess the ability to accurately assess learner engagement and discriminate between levels of learner engagement within classroom, simulation and live environments via physiological and behavioral inputs. A series of engagement classifiers were developed using cardiovascular, respiratory, electrodermal, movement, and eye-tracking features that were able to successfully classify engagement levels at an accuracy level of 85% with eye-tracking features included or 81% without eye-tracking features. This approach is capable of monitoring, assessing, and tracking learner engagement across learning situations and contexts, and providing real-time and after action feedback to support instructors in modulating learner engagement.

Wireless Sleep Apnea Detection Using Continuous Wave Quadrature Doppler Radar

A non-contact and non-invasive physiological radar monitoring system (PRMS) is introduced. The system is based on motion detection using quadrature microwave Doppler radar, eliminating the need to place sensors on the body. An algorithm was designed to perform real-time actigraphy and sleep apnea detection. The system was validated with clinical polysomnography (PSG) in a sleep study facility on ten consented volunteers with known obstructive sleep apnea. Data obtained from both PRMS and clinical PSG systems were rated by a sleep technician and show an excellent agreement in the detected apnea and hypopnea events. The apnea-hypopnea events were distinguished with an overall sensitivity of 86%, the specificity of 91% and accuracy of 92%.

Evolution of the mechanical properties of Ti-based intermetallic thin films doped with different metals to be used as biomedical devices

This study reports the assessment of the mechanical properties of intermetallic titanium thin films, doped with different amounts of aluminium, copper, silver, and gold, aiming their use as biopotential electrodes for non-invasive physiological monitoring. The four binary thin film systems, Ti-Me (Me = Al, Cu, Ag, Au), were prepared by DC magnetron sputtering, placing different number of Me pellets on a pure Ti target. The use of a Ti-composed target gave rise to a wide range of compositions, resulting in three distinctive zones of (micro)structural features, identified in all the prepared systems. In the first zone, a Ti-rich one, the films behaved like solid solutions, developing Ti-like microstructures. As the Me/Ti atomic ratio increased, the formation of intermetallic phases played the leading role and it became possible to observe two different microstructural trends, clearly related to the Me type. This zone was identified as an intermetallic region. In the third zone, a Me-rich one, the microstructures displayed by the different films (Me/Ti > 1.0) showed to be dependent on the Ti solubility into Me. The assessment of the mechanical properties revealed an improved hardness and stiffness with the Me addition, directly related to the formation of intermetallic compounds in different degrees of crystallinity. Moreover, the adhesive strength between the substrate and the coating was higher for the films deposited in the intermetallic zone, more evident in the films prepared with Au, Cu and Ag, in this order. The hardness enhancement was especially evident for the thin films presenting microstructures typical of thin film metallic glasses (TFMGs), Ti-Au and Ti-Cu, about twice the values exhibited by the Ti-Al and Ti-Ag ones. Furthermore, the toughness of these metallic glass-like thin film systems was remarkable, more evident within the Ti-rich zone, presenting H/E ratios close to 0.1 and good elastic recoveries. In contrast, the typical columnar morphologies, combined with the brittle intermetallic structures of the Ti-Ag and Ti-Al films, proved to be less resistant to the plastic deformation (H/E ≤ 0.04), despite the improved elasticity presented by the Ag-rich films.

Fatigue assessment through non-invasive physiological monitoring in military performance: protocol for a systematic review

During military operations, soldiers often encounter extreme environmental, metabolic and neuropsychiatric conditions, which combined lead to a fatigue status that can cause serious physiological impairments, decreasing military performance on the battlefield. Comprehensive studies in realistically stressful environments are essential to expand the knowledge regarding the consequences of real-life stress exposure, facilitate development of operationally-useful techniques and promote the conception of improved treatments. Therefore, a systematic review is proposed to obtain relevant information about fatigue assessment through multiple physiological parameters in the military context, to focus on determining the associations between fatigue and physiological response in order to plan in the future adequate interventions to prevent related negative consequences. Thus, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) Statement, this systematic review protocol was elaborated in order to present adequate guidelines to develop a research that can provide appropriate results to fulfil the sought objective. Five databases will be accessed (SCOPUS, PubMed, Science Direct, Medline and Web of Science) and a total of 9 combinations of keywords will be used. This protocol is registered in PROSPERO under the code of PROSPERO CRD42018105833.

A physicist’s view of homeostasis: how time series of continuous monitoring reflect the function of physiological variables in regulatory mechanisms

Objective: Homeostasis is one of the key concepts of physiology and the basis to understand chronic-degenerative disease and human ageing, but is difficult to quantify in clinical practice. The variability of time series resulting from continuous and non-invasive physiological monitoring is conjectured to reflect the underlying homeostatic regulatory processes, but it is not clear why the variability of some variables such as heart rate gives a favourable health prognosis whereas the variability of other variables such as blood pressure implies an increased risk factor. The purpose of the present contribution is to quantify homeostasis using time-series analysis and to offer an explanation for the phenomenology of physiological time series. Approach: Within the context of network physiology, which focusses on the interactions between various variables at multiple scales of time and space, it may be understood that different physiological variables may play distinct roles in their respective regulatory mechanisms. In the present contribution, we distinguish between regulated variables, such as blood pressure or core temperature, and physiological responses, such as heart rate and skin temperature. Main results: We give evidence that in optimal conditions of youth and health the former are characterized by Gaussian statistics, low variability and represent the stability of the internal environment, whereas the latter are characterized by non-Gaussian distributions, large variability and reflect the adaptive capacity of the human body; in the adverse conditions of ageing and/or disease, adaptive capacity is lost and the variability of physiological responses is diminished, and as a consequence the stability of the internal environment is compromised and its variability increases. Significance: Time-series analysis allows one to quantify homeostasis in the optimal conditions of youth and health and the degradation of homeostasis or homeostenosis in the adverse conditions of ageing and/or disease, and may offer an alternative approach to diagnosis in clinical practice.

Sustainable Energy Generation from Piezoelectric Biomaterial for Noninvasive Physiological Signal Monitoring

Sustainable development of self-powered wearable electronics relies on bioinspired piezoelectric materials which could transduce minute deformation of human skin. In this work, fish-skin-based sustainable energy production is discussed in light of structure–property correlation. The developed energy harvester acts as a sensor that interacts with human body parts to monitor real-time physiological signals. Self-assembled collagen nanofibrils comprising fish skin show stable crystalline structure and possess nonlinear electrostriction effect without any electrical poling treatment. A fish-skin-based nanogenerator (FSKNG)/pressure sensor is ultrasensitive (sensitivity ∼27 mV N–1) and highly durable (over 75 000 cycles) and possesses very fast response time (∼4.9 ms). Importantly, in response to the external pressure (∼1.8 MPa), FSKNG generates open-circuit voltage, Voc ∼ 2 V, and short-circuit current, Isc ∼ 20 nA, due to inherent piezoelectric effect. The magnitude of the generated power (∼0.75 mW m–2) turn...

Bio-assembled, piezoelectric prawn shell made self-powered wearable sensor for non-invasive physiological signal monitoring

A human interactive self-powered wearable sensor is designed using waste by-product prawn shells. The structural origin of intrinsic piezoelectric characteristics of bio-assembled chitin nanofibers has been investigated. It allows the prawn shell to make a tactile sensor that performs also as a highly durable mechanical energy harvester/nanogenerator. The feasibility and fundamental physics of self-powered consumer electronics even from human perception is highlighted by prawn shells made nanogenerator (PSNG). High fidelity and non-invasive monitoring of vital signs, such as radial artery pulse wave and coughing actions, may lead to the potential use of PSNG for early intervention. It is presumed that PSNG has enormous future aspects in real-time as well as remote health care assessment.

Human skin interactive self-powered wearable piezoelectric bio-e-skin by electrospun poly-l-lactic acid nanofibers for non-invasive physiological signal monitoring.

Flexible and wearable piezoelectric bio e-skin (PBio-e-skin) based on electrospun poly(l-lactic acid) PLLA nanofiber membrane is demonstrated for non-invasive human physiological signal monitoring and detecting dynamic tactile stimuli. The molecular orientations of the C[double bond, length as m-dash]O dipoles by electrospinning technique result in a longitudinal piezoelectric charge co-efficient (d33) value of ∼(3 ± 1) pm V-1 realized by piezoresponse force microscopy, allowing the PBio-e-skin for pressure sensing applications. The robust mechanical strength (Young's modulus ∼50 MPa) of nanofiber membrane ensures PBio-e-skin's superior operational stability over 375 000 cycles. Owing to the superior mechanosensitivity of ∼22 V N-1, PBio-e-skin has the ability to measure subtle movement of muscle in the internal organs such as esophagus, trachea, motion of joints and arterial pressure by recognition of strains on human skin. This flexible and light weight PBio-e-skin precisely detects vital signs and provides important clinical insights without using any external power source. Eventually, the low cost, environmental friendly PBio-e-skin will have a huge impact in a broad range of applications including self-powered wearable health care systems, human-machine interfacing devices, artificial intelligence and prosthetic skin.

Implementation of a novel postoperative monitoring system using automated Modified Early Warning Scores (MEWS) incorporating end-tidal capnography.

Modified Early Warning Scores (MEWS) provide real-time vital sign (VS) trending and reduce ICU admissions in post-operative patients. These early warning calculations classically incorporate oxygen saturation, heart rate, respiratory rate, systolic blood pressure, and temperature but have not previously included end-tidal CO2 (EtCO2), more recently identified as an independent predictor of critical illness. These systems may be subject to failure when physiologic data is incorrectly measured, leading to false alarms and increased workload. This study investigates whether the implementation of automated devices that utilize ongoing vital signs monitoring and MEWS calculations, inclusive of a score for end-tidal CO2 (EtCO2), can be feasibly implemented on the general care hospital floor and effectively identify derangements in a post-operative patient's condition while limiting the amount of false alarms that would serve to increase provider workload. From July to November 2014, post-operative patients meeting the inclusion criteria (BMI>30kg/m2, history of obstructive sleep apnea, or the use of patient-controlled analgesia (PCA) or epidural narcotics) were monitored using automated devices that record minute-by-minute VS included in classic MEWS calculations as well as EtCO2. Automated messages via pagers were sent to providers for instances when the device measured elevated MEWS, abnormal EtCO2, and oxygen desaturations below 85%. Data, including alarm and message details from the first 133 patients, were recorded and analyzed. Overall, 3.3 alarms and pages sounded per hour of monitoring. Device-only alarms sounded 2.7 times per hour-21% were technical alarms. The remaining device-only alarms for concerning VS sounded 2.0/h, 70% for falsely recorded VS. Pages for abnormal EtCO2 sounded 0.4/h (82% false recordings) while pages for low blood oxygen saturation sounded 0.1/h (55% false alarms). 143 times (0.1 pages/h) the devices calculated a MEWS warranting a page (rise in MEWS by 2 or 5 or greater)-62% were false scores inclusive of falsely recorded VS. An abnormal EtCO2 value resulted in or added to an elevated MEWS score in 29% of notifications, but 50% of these included a falsely abnormal EtCO2 value. To date, no adverse events have occurred. There were no statistically significant demographic, post-operative condition, or pre-existing comorbidity differences between patients who had a majority of true alarms from those who had mostly false-positive alarms. Although not statistically significant, the group of patients in whom automated MEWS suggested greater utility included those with a history of hypertension (p=0.072) and renal disease (p=0.084). EtCO2 monitoring was more likely to be useful in patients with a history of type 2 diabetes, coronary artery disease, and obstructive sleep apnea (p<0.05). These patients were also more likely to have been on a PCA post-operatively (p<0.05). Overall, non-invasive physiologic monitoring incorporating an automated MEWS system, modified to include end-tidal CO2 can be feasibly implemented in a hospital ward. Further study is needed to evaluate its clinical utility, including an end-tidal CO2 score, is feasibly implemented and can be useful in monitoring select post-operative patients for derangements in physiologic metrics. Like any other monitoring system, false alarms may occur at high rates. While further study is needed to determine the additive utility of EtCO2 in MEWS calculations, this study suggests utility of EtCO2 in select post-operative patients.