Skin Temperature Monitoring Research Articles

Ultra-Thin Highly Sensitive Electronic Skin for Temperature Monitoring

Electronic skin capable of reliable monitoring of human skin temperature is crucial for the advancement of non-invasive clinical biomonitoring, disease diagnosis, and health surveillance. Ultra-thin temperature sensors, with excellent mechanical flexibility and robustness, can conformably adhere to uneven skin surfaces, making them ideal candidates. However, achieving high sensitivity often demands sacrificing flexibility, rendering the development of temperature sensors combining both qualities a challenging task. In this study, we utilized a low-cost drop-casting technique to print ultra-thin and lightweight (thickness: approximately 3 µm, weight: 0.61 mg) temperature sensors based on a combination of vanadium dioxide and PEDOT:PSS at room temperature and atmospheric conditions. These sensors exhibit high sensitivity (temperature coefficient of resistance: −5.11%/°C), rapid response and recovery times (0.36 s), and high-temperature accuracy (0.031 °C). Furthermore, they showcased remarkable durability in extreme bending conditions (bending radius = 400 µm), along with stable electrical performance over approximately 2400 bending cycles. This work offers a low-cost, simple, and scalable method for manufacturing ultra-thin and lightweight electronic skins for temperature monitoring, which seamlessly integrate exceptional temperature-measuring capabilities with optimal flexibility.

A polyester- stainless steel based smart wristband sensor for skin temperature monitoring

This study presents the development and characterization of a novel textile-based wristband sensor for continuous temperature monitoring. The sensor, woven with a blend of polyester-stainless steel and polyester-cotton yarns, exhibited high sensitivity (0.0315/°C) and a rapid response time (∼35 sec). Stainless steel was selected for its excellent electrical conductivity and biocompatibility, crucial for accurate and safe skin contact applications, while polyester and cotton contribute its lightweight, breathable, and durable properties, ensuring prolonged comfort and wearability. Through systematic testing and optimization, the sensor’s sensitivity was fine-tuned by adjusting the number and length of conductive yarns. The study also introduced a theoretical resistance equivalent model, comparing its theoretical sensitivity with experimental findings. The sensor, lightweight and cost-effective, proved comfortable during 8–10 h of continuous wear. This study addresses challenges faced by existing textile temperature sensors and offers a reliable alternative with high linearity, repeatability, and suitability for individuals with sensitive skin.

Enhancing Early Detection of Sepsis in Neonates through Multimodal Biosignal Integration: A Study of Pulse Oximetry, Near-Infrared Spectroscopy (NIRS), and Skin Temperature Monitoring.

Sepsis continues to be challenging to diagnose due to its non-specific clinical signs and symptoms, emphasizing the importance of early detection. Our study aimed to enhance the accuracy of sepsis diagnosis by integrating multimodal monitoring technologies with conventional diagnostic methods. The research included a total of 121 newborns, with 39 cases of late-onset sepsis, 35 cases of early-onset sepsis, and 47 control subjects. Continuous monitoring of biosignals, including pulse oximetry (PO), near-infrared spectroscopy (NIRS), and skin temperature (ST), was conducted. An algorithm was then developed in Python to identify early signs of sepsis. The model demonstrated the capability to detect sepsis 6 to 48 h in advance with an accuracy rate of 87.67 ± 7.42%. Sensitivity and specificity were recorded at 76% and 90%, respectively, with NIRS and ST having the most significant impact on predictive accuracy. Despite the promising results, limitations such as sample size, data variability, and potential biases were noted. These findings highlight the critical role of non-invasive biosensing methods in conjunction with conventional biomarkers and cultures, offering a strong foundation for early sepsis detection and improved neonatal care. Further research should be conducted to validate these results across different clinical settings.

All-in-One, Wireless, Multi-Sensor Integrated Athlete Health Monitor for Real-Time Continuous Detection of Dehydration and Physiological Stress.

Athletes are at high risk of dehydration, fatigue, and cardiac disorders due to extreme performance in often harsh environments. Despite advancements in sports training protocols, there is an urgent need for a non-invasive system capable of comprehensive health monitoring. Although a few existing wearables measure athlete's performance, they are limited by a single function, rigidity, bulkiness, and required straps and adhesives. Here, an all-in-one, multi-sensor integrated wearable system utilizing a set of nanomembrane soft sensors and electronics, enabling wireless, real-time, continuous monitoring of saliva osmolality, skin temperature, and heart functions is introduced. This system, using a soft patch and a sensor-integrated mouthguard, provides comprehensive monitoring of an athlete's hydration and physiological stress levels. A validation study in detecting real-time physiological levels shows the device's performance in capturing moments (400-500s) of synchronized acute elevation in dehydration (350%) and physiological strain (175%) during field training sessions. Demonstration with a few human subjects highlights the system's capability to detect early signs of health abnormality, thus improving the healthcare of sports athletes.

Cost-effectiveness of temperature monitoring to help prevent foot ulcer recurrence in people with diabetes: A multicenter randomized controlled trial.

Diabetes-related foot ulcers are common, costly, and frequently recur. Multiple interventions help prevent these ulcers. However, none of these have been prospectively investigated for cost-effectiveness. Our aim was to evaluate the cost-effectiveness of at-home skin temperature monitoring to help prevent diabetes-related foot ulcer recurrence. Multicenter randomized controlled trial. We randomized 304 persons at high diabetes-related foot ulcer risk to either usual foot care plus daily at-home foot skin temperature monitoring (intervention) or usual care alone (control). Primary outcome was cost-effectiveness based on foot care costs and quality-adjusted life years (QALY) during 18 months follow-up. Foot care costs included costs for ulcer prevention (e.g., footwear, podiatry) and for ulcer treatment when required (e.g., consultation, hospitalisation, amputation). Incremental cost-effectiveness ratios were calculated for intervention versus usual care using probabilistic sensitivity analysis for willingness-to-pay/accept levels up to €100,000. The intervention had a 45% probability of being cost-effective at a willingness-to-accept of €50,000 per QALY lost. This resulted from (non-significantly) lower foot care costs in the intervention group (€6067 vs. €7376; p=0.45) because of (significantly) fewer participants with ulcer recurrence(s) in 18months (36% vs. 47%; p=0.045); however, QALYs were (non-significantly) lower in the intervention group (1.09 vs. 1.12; p=0.35), especially in those without foot ulcer recurrence (1.09 vs. 1.17; p=0.10). At-home skin temperature monitoring for diabetes-related foot ulcer prevention compared with usual care is at best equally cost-effective. The intervention resulted in cost-savings due to preventing foot ulcer recurrence and related costs, but this came at the expense of QALY loss, potentially from self-monitoring burdens.

Development of a Remote Health-Monitoring System for Frail People: A Preliminary Study.

Respiratory and cardiovascular functions decline with age in elderly individuals. Consequently, the incidence of chronic respiratory and cardiovascular diseases increases with age. Heart disease and pneumonia are the leading causes of death in Japan. Given the pathophysiological nature of these diseases, patients inevitably require monitoring of their cardiac and pulmonary functions, such as heart rate and arterial blood oxygenation, as systemic parameters. In addition, monitoring skin temperature and humidity as local parameters is preferable for elderly individuals to maintain healthy daily conditions. In the present study, we developed a wearable vital sign monitoring system and validated the accuracy of the device under development as compared to authorised medical devices that measure these systemic and local parameters in the peripheral tissue of the palm. For the systemic parameters, mean values showed no significant differences between the two devices, but the data bias was greater for the device under development. For the local parameters, mean values showed significant differences between the two devices; however, the data bias was the same for both devices. The acceptable data acquisition of the device under development was approximately 89%, with error acquisition mainly caused by the measurement of systemic parameters. We conclude that further improvements in measurement of systemic parameters are required to increase the data acquisition beyond 90%.

Reviewing Recommendations From the IWGDF 2023 Guidelines on the Diagnosis and Treatment of Active Charcot Neuro-Osteoarthropathy: Highlighting the Role of Temperature Monitoring With Illustrative Case Reports

The International Working Group on the Diabetic Foot (IWGDF) has consistently published evidence-based guideline recommendations on the prevention and management of diabetes-related foot complications. In 2023, the group published their first guidelines on the diagnosis and treatment of Charcot neuro-osteoarthropathy (CNO) in persons with diabetes. The guidelines highlight 26 recommendations based on 4 categories: diagnosis, identification of remission, treatment, and prevention of re-activation. As reviewed in the guidelines, there are 2 recommendations suggesting the use of temperature assessment and monitoring as a tool for management of patients with CNO. Utilizing the systematic review and the GRADE system of evaluation, the authors deemed the level of evidence around temperature monitoring and Charcot to be low with a conditional recommendation for use. The purpose of this manuscript is to summarize the IWGDF guidelines while highlighting the role of foot temperature monitoring. Several case examples are given to illustrate the use of temperature monitoring in patients with CNO. Until there are guidelines determining active vs quiescent CNO, skin temperature monitoring can be a fast, easy-to-use, and effective tool for the clinician.

ThermICA: Novel Approach for a Multivariate Analysis of Facial Thermal Responses.

Infrared Thermography (IRT) has been used to monitor skin temperature variation in a contactless manner, in both clinical medicine and psychophysiology. Here, we introduce a new methodology to obtain information about autonomic correlates related to perspiration, peripheral vasomotility, and respiration from infrared recordings. Our approach involves a model-based decomposition of facial thermograms using Independent Component Analysis (ICA) and an ad-hoc preprocessing procedure. We tested our approach on 30 healthy volunteers whose psychophysiological state was stimulated as part of an experimental protocol. Within-subject ICA analysis identified three independent components demonstrating correlations with the reference physiological signals. Moreover, a linear combination of independent components effectively predicted each physiological signal, achieving median correlations of 0.9 for electrodermal activity, 0.8 for respiration, and 0.73 for photoplethysmography peaks envelope. In addition, we performed a cross-validated inter-subject analysis, which allows to predict physiological signals from facial thermograms of unseen subjects. Our findings validate the efficacy of features extracted from both original and thermal-derived signals for differentiating experimental conditions. This outcome emphasizes the sensitivity and promise of our approach, advocating for expanded investigations into thermal imaging within biomedical signal analysis. It underscores its potential for enhancing objective assessments of emotional states.

Thermoregulation during Field Exercise in Horses Using Skin Temperature Monitoring.

Hyperthermia and exertional heat illness (EHI) are performance and welfare issues for all exercising horses. Monitoring the thermoregulatory response allows for early recognition of metabolic heat accumulation during exercise and the possibility of taking prompt and effective preventative measures to avoid a further increase in core body temperature (Tc) leading to hyperthermia. Skin temperature (Tsk) monitoring is most used as a non-invasive tool to assess the thermoregulatory response pre- and post-exercise, particularly employing infrared thermographic equipment. However, only a few studies have used thermography to monitor skin temperature continuously during exercise. This commentary provides an overview of studies investigating surface skin temperature mainly by infrared thermography (IRT) during exercise. The scientific evidence, including methodologies, applications, and challenges associated with (continuous) skin temperature monitoring in horses during field exercise, is discussed. The commentary highlights that, while monitoring Tsk is straightforward, continuous Tsk alone does not always reliably estimate Tc evolvement during field exercise. In addition, inter-individual differences in thermoregulation need to be recognized and accounted for to optimize individual wellbeing. With the ongoing development and application of advanced wearable monitoring technology, there may be future advances in equipment and modeling for timely intervention with horses at hyperthermic risk to improve their welfare. However, at this point, infrared thermographic assessment of Tsk should always be used in conjunction with other clinical assessments and veterinary examinations for a reliable monitoring of the welfare of the horse.

Monitoring Baby Incubator Central through Internet of Things (IoT) based on Raspberry Pi Zero W with Computer Monitoring)

Premature infants, with a gestational age of 37 weeks or less and weighing less than 2500 grams, face challenges in adapting to the outside world due to the underdeveloped state of their organ systems. Special care is essential to support their growth and development, including maintaining optimal temperature, humidity, and oxygen levels similar to those experienced in the mother's womb. Baby incubators play a crucial role in providing these conditions. This study aims to develop a convenient monitoring tool for midwives and healthcare workers responsible for multiple baby incubators. The tool operates independently and is compatible with various brands of baby incubators. Leveraging an IoT system, it utilizes ESP32 and Raspberry Pi Zero W modules for data transmission. The tool incorporates a DS18B20 sensor for monitoring skin temperature and a DHT22 sensor for monitoring the temperature inside the incubator chamber. Using a pre-experimental design with an after-only research design, the tool's measurements are compared against an incubator analyzer. The study reveals that the developed module still exhibits some measurement errors. However, despite these limitations, the research is expected to greatly assist medical personnel in simultaneously monitoring multiple baby incubators.
 Keywords : Premature infants, Baby incubators, IoT, Temperature, ESP32, Raspberry Pi Zero W

Shape memory alloy based smart compression stocking and real-time health monitoring app for deep venous thrombosis

Deep venous thrombosis (DVT) is a severe venous disease with high incidence and mortality rate. Patients suffering from DVT have poor quality of life due to continuous sequela. Prophylaxis is applied on high-risk individuals while clinical researches have demonstrated the efficacy of graduated compression stockings (GCSs) in reducing DVT incidence. However, the prophylactic effect of conventional GCS on DVT in daily life does not meet the expectation due to its disadvantages such as low compliance and static pressure. For the purpose of superior prevention, a smart graduated compression stocking (SGCS) based on shape memory alloy (SMA) was designed, prototyped and tested in this research. A related mobile App was designed to modulate dynamic pressure and monitor health conditions such as temperature and pulse during the application of the SGCS. Experimental results showed that the prototype was able to provide clinical-standard pressure (at least 15 mmHg to 21 mmHg), three levels of adjustable dynamic pressure and low dressing difficulty while the App guaranteed the real-time physiological signs monitoring of skin temperature and dorsalis pedis artery pulse.

Design and development of a multifunctional moxibustion treatment machine based on heat-sensitive moxibustion therapy

A multifunctional moxibustion treatment machine is designed and developed to assist the heat-sensitive moxibustion therapy. Through the motion control of the stepping motor by programmable logic controller (PLC), the automatic control is obtained for the acupoint detection of heat-sensitive moxibustion therapy and the manual operation of moxibustion. The skin temperature is monitored in real-time, using infrared non-contact temperature measurement technology. Based on the deviation of the temperature set value and the monitoring one, the distance between the moxibustion device and the exerted region is adjusted automatically by PLC so that the temperature is controlled practically. The multifunctional moxibustion treatment machine based on the heat-sensitive moxibustion therapy is capable of the operation control of mild moxibustion, circling moxibustion, sparrow-pecking moxibustion and along-meridian moxibustion techniques, as well as real-time monitoring of skin temperature. The temperature change curve of this machine is coincident with that obtained by the manual operation of heat-sensitive moxibustion. This multifunctional moxibustion treatment machine assists the delivery of heat-sensitive moxibustion therapy and it is satisfactory in temperature control and precise in operation.

Twin‐Wire Sensor Networks

AbstractA fundamental limit to high‐density sensing is that adding sensors increases the number of wires, pads, and interconnections. This problem is even worse for low‐values resistive or impedance sensors which, for high accuracy, require 4‐wire measurements. Here, twin‐wire sensor networks are described which enable 4‐wire measurements with significantly fewer wires, pads, and interconnections. The effects of the resistor noise can be minimized by minimum‐resistance sensing paths. A single chopper switch and straightforward digital operations can reject the equivalent input offset and low‐frequency noise voltages of the instrumentation amplifier, thus requiring no hardware changes. The inclusion in the network of a reference resistor can compensate the errors of both the biasing current and the instrumentation amplifier voltage gain. For validation, an extremely compact, robust, and easy‐to‐connect flexible‐PCB twin‐wire 29‐temperature‐sensors network requiring only 32 pads is demonstrated. This device is placed on an anthropomorphic head phantom for detecting the temperature and location of a touching object or on the hand of a volunteer for monitoring skin temperature during mental and physical stimulations. A twin‐wire 29‐photoresistors network is also presented. The strategies reported here can be applied to any high‐density array of resistive or impedance sensors (temperature, strain, blood flow, light, etc.) and may find wide application in robotics and wearable or epidermal devices.

Multifunctional Wearable System for Mapping Body Temperature and Analyzing Sweat.

Integrated wearable bioelectronic health monitoring systems have revealed new possibilities for collecting personalized physiological information. Wearable sweat sensors have the potential to noninvasively measure valuable biomarkers. Mapping sweat and skin-temperature throughout the body can provide detailed information on the human body. However, existing wearable systems cannot evaluate such data. Here, we report a multifunctional wearable platform that can wirelessly measure local sweat loss, sweat chloride concentration, and skin temperature. The approach combines a reusable electronics module to monitor skin temperature and a microfluidic module for monitoring sweat loss and sweat chloride concentration. The miniaturized electronic system takes temperature measurements from the skin and wirelessly transmits the obtained data to a user device using Bluetooth technology. In contrast, the microfluidic system provides accurate colorimetric analysis of the chloride concentration and sweat loss. Thus, this integrated wearable system has great application potential in individualized health management systems for sports researchers and competitors and can also be applied in clinical settings.

P160 Pilot study to determine whether skin blood flow, oxygenation and skin colour are related in patients with systemic sclerosis

Abstract Background/Aims Improved treatments are needed for Raynaud’s phenomenon. Clinical trials can be difficult since it is challenging to measure Raynaud’s ‘attacks’ outside the laboratory. Ambulatory monitoring would allow testing of new treatments in the patients’ home environment where they usually experience attacks, thus allowing a much more realistic assessment of efficacy. Smartphone technology advancements mean that ambulatory monitoring of, and capture of biomarkers from, patients is now possible and could facilitate clinical trials. The aim of this study was to establish whether smartphone monitoring of skin temperature, an indirect measure of blood flow, and changes in skin colour as compared to laboratory measures of oxygenation could inform outcome measures in future clinical trials. Methods Following acclimatisation in a temperature-controlled room, participants underwent finger occlusion in order to simulate a decrease in perfusion and oxygenation. Simultaneous images were taken of the whole hand at baseline, during occlusion, at release and at 1 and 5 minute(s) post-release. Images of skin temperature (henceforth referred to as blood flow) and skin colour were taken with smartphone thermography (FLIRone) and camera respectively. Oxygenation was measured with multispectral imaging. Blood flow, colour and oxygenation data were extracted from images using automated bespoke software that identified the boundary of the hand and selected regions of interest. Colour data was split into red, green and blue channels. Data were plotted over time at each time point. Results Thirty patients with systemic sclerosis (SSc, median 62 interquartile range [57-69] years of age, 26[87%] female, duration of Raynaud’s phenomenon 20[10-32] years, duration of SSc 17[6-25] years, 6[20%] smokers) and 25 healthy controls (53[40-56] years of age, 23[92%] female, 0[0%] smokers) were recruited into the study. The measures of blood flow, colour (red channel) and oxygenation followed similar trajectories over time for both patients and controls (decreasing during occlusion and increasing post occlusion). Oxygenation data was significantly different between patients and controls for baseline to occlusion (-0.24[-0.30 - -0.14] vs. -0.34[-0.46 - -0.26] arb units, p = 0.004) and occlusion to release (0.42[0.12-0.53] vs. 0.74[0.64-0.82] arb units, p < 0.0001). Grouping all data together (at occlusion to release), correlations were identified between colour (red channel) and blood flow r=-0.36 p = 0.003; colour (red channel) and oxygenation r = 0.31 p = 0.003 and between oxygenation and blood flow r=-0.38 p = 0.003. Conclusion Blood flow, skin colour and oxygenation in both patients with SSc and healthy controls follow similar distributions with time under occlusion and release. Blood flow, skin colour and oxygenation are related suggesting that measuring skin colour (redness) may be an alternative way to assess perfusion and oxygenation. Further larger studies are now required to validate this. Smartphone measures of outcomes offer promise for the future of ambulatory monitoring for clinical trials of Raynaud’s phenomenon. Disclosure G. Dinsdale: None. C. Heal: None. J. Manning: None. S. Wilkinson: None. J. Wilkinson: None. M. Dickinson: None. A. Herrick: None. A. Murray: None.

An Infrared Temperature Correction Method for the Skin Temperature of Pigs in Infrared Images

Accurately measuring the skin temperature of pigs is essential to large-scale pig farming for health monitoring, as well as disease detection and prevention. Infrared thermography (IRT) is a promising technology for the non-invasive measuring of pig skin temperature. However, the distance and angle of view of measurement greatly affect the accuracy of IRT-measured temperature. To improve the accuracy of the measurement, this study starts with evaluating the effects of four parameters on the measurement of skin temperature: horizontal distance, camera height, pig height, and angle of view between the object and the IRT camera. It follows by proposing a mathematical model describing the relationship between the real skin temperature and the four parameters through means of response surface methodology. A correction algorithm is then developed based on the mathematical model to improve the measuring accuracy. In order to evaluate the performance of the correction algorithm, the measured skin temperatures before and after correction are compared with the actual ones. The comparison was carried out in an experimental pig farm with 25 randomly selected pigs. The results show that the mean relative error before the correction was −4.64% and the mean relative error after the correction was −0.70%. This study demonstrates that the new infrared temperature correction method is effective and can benefit skin temperature monitoring for commercial pig farms.

Detection of Fever Using Continuous Skin Temperature Monitoring in Hospitalized Older Adults

The continuous monitoring of body surface temperature has been proven to help detect potential fever events in hospitalized patients. However, the efficacy of using body surface temperature to detect fever in older adults remains unclear due to the relatively low and slower-to-change body surface temperature in this population. This study was designed to investigate 1) the relationship between changes in body surface and routine tympanic temperatures, 2) the correlation between body surface temperature measurement frequency and detection of fever, and 3) the factors related to the incidence of fever in hospitalized older adults. A prospective study was conducted on 33 hospitalized older adults aged 65 years or older who were suspected to have or diagnosed with an infection in an infectious disease and medical ward at a medical center in southern Taiwan from March to November 2020. Demographic, routine tympanic temperature, and heart rate data were collected by reviewing the participants' medical records. Body surface temperatures were monitored continuously using HEARThermo every 10 seconds until one of the following conditions were met: hospital discharge, no fever for three continuous days, and HEARThermo was removed. Descriptive analysis was used to compare the variations in body surface temperature and routine tympanic temperature measurements. Pearson correlation was used to analyze the correlation between different measurement frequencies and fever events. Finally, mixed effects logistic regression was used to analyze the factors significantly related to fever events. Seven hundred and twenty routine body temperature measurements were taken, with 209 (29.0%) fever events detected in 23 (69.7%) of the participants. The body surface temperatures were more closely correlated with tympanic temperatures during fever events than non-fever events (r = .260, p < .001). More fever events were detected using body surface temperature monitoring frequencies of every 10 seconds and every 1 minute. After controlling for demographic factors, the results of the mixed effect model indicate that body surface temperature and heart rate are significant factors related to fever events in hospitalized older adults (odds ratio, OR: 1.74, p < .001; OR: 1.11, p < .001). The continuous monitoring of body surface temperature may improve the detection of fever events in hospitalized older adults. The application of wearable devices and cloud platforms may further facilitate the real-time assessment and care capabilities of nurses, thus reducing their workload and improving care quality.

Remote Monitoring of Skin Temperature Through a Wristband Employing a Printed VO Sensor

The need for highly sensitive, environmentally stable, mechanically flexible, and low-cost temperature sensors for on-body measurements has been increasing with the wide adoption of personal healthcare-Internet-of-Things (H-IoT) devices. Printed electronics (PE) is a good platform for such sensors because it enables the realization of flexible devices through simple and rapid methods at a relatively low cost. However, previously reported printed temperature sensors suffer from poor sensitivity and/or environmental instability. In this article, we report a custom tungsten (W)-doped vanadium dioxide (VO2) ink-based screen-printed temperature sensor having the highest temperature coefficient of resistance (TCR) of 2.78% C-1 with a resolution of 0.1 °C between 30 °C and 40 °C. To protect it from environmental effects, a fluoropolymer-basedpassivation layer is added for accurate temperature readings even in 90% relative humidity. The sensor is printed on a flexible substrate and shows minimal deterioration in performance over 1000 bending cycles. For wearability and remote monitoring, the sensor is integrated with a custom Bluetooth low energy (BLE) wireless readout in the form of wristband. The BLE readout comprises an ultrathin and flexible patch antenna optimized for both BLE bandwidth (BW) and human wearability. It demonstrates a minimal specific absorption rate (SAR) value of only 0.068 W/kg, making it safe to wear. Despite the antenna’s thin structure (0.004λ), it has a gain of 1.65 dBi, enabling an excellent communication range. The proposed wristband is tested on ten volunteers and under daily activities, which shows promising results with a maximum error of 0.16 °C with reference to those of a commercial thermometer.

Large-Scale Ultra-Robust MoS2 Patterns Directly Synthesized on Polymer Substrate for Flexible Sensing Electronics.

Synthesis of large-area patterned MoS2 is considered the principle base for realizing high-performance MoS2 -based flexible electronic devices. Patterning and transferring MoS2 films to target flexible substrates, however, require conventional multi-step photolithography patterning and transferring process, despite tremendous progress in the facilitation of practical applications. Herein, an approach to directly synthesize large-scale MoS2 patterns that combines inkjet printing and thermal annealing is reported. An optimal precursor ink is prepared that can deposit arbitrary patterns on polyimide films. By introducing a gas atmosphere of argon/hydrogen (Ar/H2 ), thermal treatment at 350°C enables an in situ decomposition and crystallization in the patterned precursors and, consequently, results in the formation of MoS2 . Without complicated processes, patterned MoS2 is obtained directly on polymer substrate, exhibiting superior mechanical flexibility and durability (≈2% variation in resistance over 10,000 bending cycles), as well as excellent chemical stability, which is attributed to the generated continuous and thin microstructures, as well as their strong adhesion with the substrate. As a step further, this approach is employed to manufacture various flexible sensing devices that are insensitive to body motions and moisture, including temperature sensors and biopotential sensing systems for real-time, continuously monitoring skin temperature, electrocardiography, and electromyography signals.

A novel method to selectively elicit cold sensations without touch

BackgroundThermal and tactile stimuli are transduced by different receptor classes. However, mechano- and thermo-sensitive afferents interact at spinal and supraspinal levels. Yet, most studies on responses to cooling stimuli are confounded by mechanical contact, making these interactions difficult to isolate. Methods for precise control of non-mechanical thermal stimulations remain challenging, particularly in the cold range. New methodWe developed a non-tactile, focal, temperature-controlled, multi-purpose cooling stimulator. This method controls the exposure of a target skin region to a dry-ice source. Using a thermal camera to monitor skin temperature, and adjusting the source-skin distance accordingly, we could deliver non-tactile cooling stimuli with customisable profiles, for studying different aspects of cold sensation. ResultsTo validate our method, we measured absolute and relative thresholds for cold sensation without mechanical contact in 13 human volunteer participants, using the method of limits. We found that the absolute cold detection threshold was 32.71 oC ± 0.88 oC. This corresponded to a threshold relative to each participant’s baseline skin temperature of − 1.08 oC ± 0.37 oC. Comparisons with existing methodOur method allows cooling stimulation without the confound of mechanical contact, in a controllable and focal manner. ConclusionsWe report a non-contact cooling stimulator and accompanying control system. We used this to measure cold thresholds in the absence of confounding touch. Our method enables more targeted studies of both cold sensory pathways, and of cold-touch interactions.