Body Temperature Monitoring Research Articles

Dual-Mode Textile Sensor Based on PEDOT:PSS/SWCNTs Composites for Pressure–Temperature Detection

As an innovative branch of electronics, intelligent electronic textiles (e-textiles) have broad prospects in applications such as e-skin, human–computer interaction, and smart homes. However, it is still a challenge to distinguish multiple stimuli in the same e-textile. Herein, we propose a dual-parameter smart e-textile that can detect human pulse and body temperature in real time, with high performance and no signal interference. The doping of SWCNTs in PEDOT:PSS improves the electrical conductivity and Seebeck coefficient of the prepared composites, which results in excellent pressure and temperature-sensing properties of the PEDOT:PSS/SWCNTs/CS@PET-textile (PSCP) sensor. The dual-mode sensor has high sensitivity (32.4 kPa−1), fast response time (~21 ms), and excellent durability (>2000 times) in pressure detection. Concurrently, this sensor maintains a high Seebeck coefficient of 25 μV/K in the 0–120 K temperature range with a tremendous linear relationship. Based on impressive dual-mode sensing characteristics and independent temperature-difference- and pressure-sensing mechanisms, smart e-textile sensors realize the real-time simultaneous monitoring of weak pulse signals and human body temperature, showing great potential in medical healthcare. In addition, the potential energy is excited by the temperature gradient between the human skin and the environment, which provides a novel idea for wearable self-powered devices.

Phase Transition Driven Zn‐Ion Battery With Laser‐Processed V2C/V2O5 Electrodes for Wearable Temperature Monitoring

AbstractFlexible power supply devices present significant potential for wearable bioelectronics within the Internet of Things. Aqueous zinc‐ion batteries have emerged as a viable and safe alternative for power supply in flexible electronics. Nevertheless, typical battery behaviors are generally detrimental with unfavorable phase transition of electrodes, which invariably lead to rapid performance degradation. Here, extraordinary capacity enhancement of 150% is presented, sustained over 60 000 cycles, attained using vanadium carbide MXene (V2C)/vanadium pentoxide (V2O5) heterostructure as cathode. The unique cathode material is created through the rational engineering of MAX (V2AlC), employing a single‐step laser writing process. The ultrastable Zn ion battery stands in stark contrast to all previously reported counterparts, which typically exhibit capacity degradation within a few hundred/thousand cycles. The primary mechanisms driving this enhancement include the delamination of V2C MXene and an unexpected favorable phase transition during cycling. Additionally, a wearable power supply is constructed using a series configuration and is integrated with a commercial temperature sensor for wireless, real‐time body temperature monitoring. This study highlights the critical role of electrode design for advanced wearable bioelectronics.

Flexible, multimodal device for measurement of body temperature, core temperature, thermal conductivity and water content

Body core temperature is an important physiological indicator for self-health management and medical diagnosis. However, existing devices always fails to achieve continuous monitoring of core body temperature due to their invasive or motion-restricted measurement principles. Here, a wearable flexible device which can continuously monitor the core body temperature was developed. The flexible device integrated with fourteen temperature sensors and one thermal conductivity sensor on the polydimethylsiloxane substrate can be conformally attached to the human skin. With the wearable data processing module and wireless communication module, the continuous monitoring of the core body temperature for 24 h and the portable monitoring of the skin thermal conductivity were realized using this device. Owing to the annular distribution design of the temperature sensor and the directional heat transfer design of the thermal conductivity sensor, this device is comparable in accuracy and stability compared to standard instruments that require invasive or motion-restricted measurements.

A Randomized, Blinded, Vehicle-Controlled Dose-Ranging Study to Evaluate and Characterize Remdesivir Efficacy Against Ebola Virus in Rhesus Macaques.

Ebola virus (EBOV) causes severe disease in humans, with mortality as high as 90%. The small-molecule antiviral drug remdesivir (RDV) has demonstrated a survival benefit in EBOV-exposed rhesus macaques. Here, we characterize the efficacy of multiple intravenous RDV dosing regimens on survival of rhesus macaques 42 days after intramuscular EBOV exposure. Thirty rhesus macaques underwent surgical implantation of telemetry devices for the fine-scale monitoring of body temperature and activity, as well as central venous catheters, to enable treatment administration and blood collection. Treatment, consisting of a loading dose of RDV followed by once-daily maintenance doses for 11 days, was initiated 4 days after virus exposure when all animals were exhibiting disease signs consistent with incipient EBOV disease as well as quantifiable levels of EBOV RNA in plasma. In the RDV treatment groups receiving loading/maintenance doses of 5/2.5 mg/kg, 10/5 mg/kg, and 20/10 mg/kg, a total of 6 of 8 (75%), 7 of 8 (87.5%), and 5 of 7 (71.4%) animals survived, respectively. In the vehicle control group, one of seven animals (14.3%) survived. The improved survival rate compared to the control group was statistically significant only for the 10/5 mg/kg RDV treatment group. This treatment regimen also resulted in a significantly lower systemic viral load compared to the vehicle control after a single RDV treatment. All three RDV regimens produced a significantly lower systemic viral load after two treatments. For most animals, RDV treatment, regardless of dose, resulted in the amelioration of many of the clinical-pathological changes associated with EBOV disease in this model.

Design, Fabrication, and Wearable Medical Application of a High‐Resolution Flexible Capacitive Temperature Sensor Based on the Thermotropic Phase Transition Composites of PEO/PVDF‐HFP/H3PO4

AbstractPhase transition materials have the potential to be utilized as high‐resolution temperature‐sensitive materials. However, it is a challenge to develop them into temperature sensors with good stability and repeatability. In this work, inspired by phase transition theory and the electrical double‐layer capacitance principle, a novel high‐resolution flexible capacitive temperature sensor based on Polyethylene oxide(PEO)/Poly(vinylidene fluoride‐co‐hexafluoropropylene)/H3PO4 is proposed for the first time. By blending high and low molecular weight PEO and adding ionic solution, the proposed sensor exhibits high resolution (0.05 °C) and response speed (<12 s) within 35–43 °C. The novel introduction of a mesh structure aids the material in achieving microdomain control of PEO crystallization and improves the repeatability (Ex < 2.2%) of the sensor. The sensor is used for monitoring human body temperature and diabetic foot ulcers, and the results show that the sensor can achieve continuous and comfortable body temperature monitoring and early‐stage diabetic foot ulcer diagnosis, offering broad applications in health monitoring and rehabilitation medicine.

Flexible, stretchable multifunctional silver nanoparticles-decorated cotton textile based on amyloid-like protein aggregation for electrothermal and photothermal dual-driven wearable heater.

The design of multifunctional, high-performance wearable heaters utilizing textile substrates has garnered increasing attention, particularly in the development of body temperature and health monitoring devices. However, fabricating these multifunctional wearable heaters while simultaneously ensuring flexibility, air permeability, Joule heating performance, electromagnetic interference (EMI) shielding and antibacterial properties remains a significant challenge. This study utilizes phase transition lysozyme (PTL) film-mediated electroless deposition (ELD) technology to deposit silver nanoparticles (Ag NPs) on the cotton fabrics surface in a mild aqueous solution at room temperature, thereby constructing a wearable heater with long-term stability, high conductivity, and exceptional photothermal properties. The textiles enriched with Ag NPs exhibit remarkable electrothermal and photothermal dual-driven heating capabilities, achieving temperatures exceeding 110 °C within 50s under 2 V, or in merely a few seconds through photothermal conversion. Importantly, these textiles retain the intrinsic flexibility and breathability of the textile substrate. Furthermore, the amyloid-like protein Ag NP integrated textiles demonstrate excellent antibacterial properties, and exhibit a high EMI shielding efficiency of 50 dB within the frequency range of 8.2-12.4 GHz. Therefore, these multifunctional Ag NPs wearable heaters were expected to find applications in areas such as smart wearable clothing and future health management.

Chicken body temperature monitoring method in complex environment based on multi-source image fusion and deep learning

Severe diseases in chickens present substantial risks to poultry husbandry industry. Notably, alterations in body temperature serve as critical clinical indicators of these diseases. Consequently, timely and accurate monitoring of body temperature is essential for the early detection of severe health issues in chickens. This study presents a novel method for simultaneous body temperature detection of multiple chickens in caged poultry environments. A dataset of 2896 chicken head images was developed. The YOLOv8n-mvc model was created to accurately detect chicken head positions and extracted temperature data and distance information through the fusion of RGB, thermal infrared, and depth images. The chicken head temperature was calibrated using distance information. The YOLOv8n-mvc model established in this study achieved a precision of 91.6 %, recall of 92.5 %, F1 score of 92.0 %, and mAP@0.5 of 96.0 %. The model was successfully deployed on an edge computing device for validation tests, demonstrating its feasibility for chicken body temperature detection. This study provides a reference for developing a chicken health monitoring system based on body temperature.

Anti-interference flexible temperature-sensitive/strain-sensing aerogel fiber for cooperative monitoring of human body temperature and movement information

In recent years, multi-functional flexible sensing fibers capable of detecting various physical and chemical stimuli capabilities have made significant advancements. However, the cross-sensitivity of the sensing materials to other stimuli can considerably reduce their sensitivity and accuracy of these multifunctional fibers. In this study, we initially fabricated a blending type (BAF) and a core-sheath type (CAF) strain-sensing aerogel fiber using an optimized one-step wet spinning process. Then, we coated the aerogel fiber with cholesteric liquid crystal as the middle layer and waterborne polyurethane as the outer layer to obtain a temperature-sensitive/strain-sensing aerogel fiber (TSAF). TSAF demonstrates distinct multi-model strain sensing performance, enabling the detection of tensile strains (0.1–111.5 %), bending strains (40°–160°), and compression strains. Moreover, within the ultra-narrow temperature range of 34 °C–38 °C, TSAF undergoes reversible color transformations from yellow-green-blue-purple, against both bright and dark backgrounds. This unique feature offered high sensitivity, rapid response time, and diverse color variations. By integrating fibers into clothing, a collaborative sensing system can be established to simultaneously monitor human physiology and movement information. These advancements hold significant potential for applications in smart clothing, medical care, and other fields.

Compact Vital-Sensing Band with Uninterrupted Power Supply for Core Body Temperature and Pulse Rate Monitoring.

Although wearable devices for continuous monitoring of vital signs have undergone significant advancements, their need for frequent recharging precludes continuous operation, potentially leading to adverse outcomes being overlooked. Additionally, the scattered locations of the sensors hamper wearability. Herein, we present a compact vital-sensing band with uninterrupted power supply designed for continuous monitoring of core body temperature (CBT) and pulse rate. The band─which comprises two sensors, a power source (i.e., a flexible thermoelectric generator (TEG) and a battery), and a flexible circuit─is worn on the forearm. The CBT is calculated by measuring the skin temperature and heat flux, while a triboelectric nanogenerator-based self-powered pressure sensor is utilized for pulse rate monitoring. The TEG is a flexible unit that converts body heat into electricity, accumulating a total energy of 314 mJ (100%). Out of this total energy, only 43.2 mJ (7.2%) is utilized for CBT measurements, while the remaining 270.80 mJ (92.8%) is stored in the battery. This enables reliable and continuous operation of the vital-sensing band, highlighting its potential for use in healthcare applications.

Analysis of Body Temperature in Patients with Trauma Visiting a Local Emergency Medical Center during the SARS-CoV-2 Outbreak

Background: The study aimed to evaluate the usefulness of body temperature monitoring as a screening tool for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Methods: This retrospective study was conducted in an emergency department from January 1, 2019, to December 31, 2020. A total of 5,502 out of 9,205 patients with trauma during the pre-pandemic period and 3703 out of 9205 during the pandemic period (age ≧ 18 years old) were enrolled in the study. Data collected included sex, age, time of visit, initial and follow-up BT, Korean Triage and Acuity Scale (KTAS) score, disposition results, time of disposition, time of the first imaging study, and SARS-CoV-2 test results. Patients were divided into two groups based on their body temperature. Results: During the pandemic period, three out of 832 patients with a body temperature below 37.5°C tested positive for SARS-CoV-2 via polymerase chain reaction, while none of the 342 patients with a body temperature above 37.5°C tested positive negative. However, this was statistically insignificant. Patients with a body temperature over 37.5°C had to wait significantly longer to see a doctor, undergo imaging studies, and receive disposition, especially in non-major trauma cases. Follow-up body temperatures were significantly lower except in KTAS 1- and ICU-admitted patients. The usefulness of body temperature as a screening tool for trauma patients in the emergency department during the pandemic period is limited and could have detrimental effects on emergency department crowding.

16S rRNA Gene Sequencing Combined with Metabolomics to Explore Intestinal Flora and Metabolic Changes in Young Febrile Rats and the Mechanism of Xiangqin Jiere Granules.

Xiangqin Jiere Granules (XQJRG), a Chinese patent medicine used to treat acute fever in children caused by colds, seasonal flu, and coronavirus disease 2019has been proven to have antipyretic and anti-inflammatory effects in young febrile rats. Fever is known to affect the host-gut microbiota crosstalk. However, the pharmacological mechanism of XQJRG in this regard remains unclear. This study utilized a young febrile rat model previously reported by our team and extended the rat body temperature monitoring period following drug administration to explore the differences in efficacy between XQJRG and the commonly used pediatric antipyretic ibuprofen. Subsequently, the colonic contents of rats were analyzed using 16S rRNA gene sequencing and untargeted metabolomics. The short-chain fatty acid content was quantified using high-throughput targeted metabolomics. The expression of short-chain fatty acid receptors and pro-inflammatory genes in the colonic tissue was evaluated using quantitative real-time PCR, Western blot, and enzyme-linked immunosorbent assay. XQJRG showed a longer antipyretic duration than ibuprofen. XQJRG improved dysbiosis of the intestinal microbiota in young febrile rats, bringing its flora composition closer to that of normal rats. It significantly increased the relative abundance of s_Phascolarctobacterium_faecium and s_Roseburia_sp. related to the production of short-chain fatty acids (SCFAs), the contents of butyric acid and nonanoic acid and protein levels of SCFAs receptor GPR41. Moreover, XQJRG significantly increased the levels of metabolites with anti-inflammatory effects, reduced the contents of metabolites directly associated with fever, and decreased the levels of pro-inflammatory cytokines interleukin-1β and monocyte chemotactic protein-1 in the colon of young febrile rats to normal levels. XQJRG exhibited a more stable and persistent antipyretic effect in young febrile rats compared to ibuprofen. Its mechanism was at least partially attributed to regulating intestinal flora disorders, increasing anti-inflammatory metabolites, and inhibiting the production of inflammatory factors in young febrile rats.

LIG-Based High-Sensitivity Multiplexed Sensing System for Simultaneous Monitoring of Metabolites and Electrolytes.

With improvements in medical environments and the widespread use of smartphones, interest in wearable biosensors for continuous body monitoring is growing. We developed a wearable multiplexed bio-sensing system that non-invasively monitors body fluids and integrates with a smartphone application. The system includes sensors, readout circuits, and a microcontroller unit (MCU) for signal processing and wireless communication. Potentiometric and amperometric measurement methods were used, with calibration capabilities added to ensure accurate readings of analyte concentrations and temperature. Laser-induced graphene (LIG)-based sensors for glucose, lactate, Na+, K+, and temperature were developed for fast, cost-effective production. The LIG electrode's 3D porous structure provided an active surface area 16 times larger than its apparent area, resulting in enhanced sensor performance. The glucose and lactate sensors exhibited high sensitivity (168.15 and 872.08 μAmM-1cm-2, respectively) and low detection limits (0.191 and 0.167 μM, respectively). The Na+ and K+ sensors demonstrated sensitivities of 65.26 and 62.19 mVdec-1, respectively, in a concentration range of 0.01-100 mM. Temperature sensors showed an average rate of resistance change per °C of 0.25%/°C, within a temperature range of 20-40 °C, providing accurate body temperature monitoring.

Lignin sulfonate induced ultrafast fabrication of polypyrrole-based conductive organohydrogel for high performance flexible strain and temperature sensor

The ultrafast preparation of electrically conductive hydrogels to endow high sensing performance and temperature tolerance remains a critical challenge. Herein, lignosulfonate sodium-templated polypyrrole (LS-PPy) nanofillers were rapidly introduced into polyacrylic acid (PAA) hydrogel through ultrafast free radical polymerization in a glycerol/water binary solvent system. The resultant LS-PPy/PAA electrically conductive organohydrogel possesses satisfactory mechanical performance (strength of 56 kPa at a tensile strain of 800 %), strong adhesion, and a desirable low freezing point (−35 °C). Furthermore, this organohydrogel exhibits high strain sensitivity (gauge factor = 2.65), fast response time (∼160 ms), low signal hysteresis, and excellent cyclic stability (over 1200 cycles). And the wearable LS-PPy/PAA organohydrogel sensor could accurately and real-time monitor various intense or subtle human movements, such as joint bending, facial expression and hand writing. Besides, the developed LS-PPy/PAA temperature sensor can respond to environmental temperature variations over a wide range of −20–100 °C. High resolution of 0.5 °C with remarkable sensitivity (−0.80 %/°C and linearity of R2 = 0.99) and repeatability were achieved within 36.5–40 °C, which makes it suitable for human body temperature monitoring. All these results demonstrate the substantial prospective value of the LS-PPy/PAA hydrogel in wearable sensors and other associated fields.

A Wireless Multimodal Physiological Monitoring ASIC for Animal Health Monitoring Injectable Devices.

Utilizing injectable devices for monitoring animal health offers several advantages over traditional wearable devices, including improved signal-to-noise ratio (SNR) and enhanced immunity to motion artifacts. We present a wireless application-specific integrated circuit (ASIC) for injectable devices. The ASIC has multiple physiological sensing modalities including body temperature monitoring, electrocardiography (ECG), and photoplethysmography (PPG). The ASIC fabricated using the CMOS 180 nm process is sized to fit into an injectable microchip implant. The ASIC features a low-power design, drawing an average DC power of 155.3 µW, enabling the ASIC to be wirelessly powered through an inductive link. To capture the ECG signal, we designed the ECG analog frontend (AFE) with 0.3 Hz low cut-off frequency and 45-79 dB adjustable midband gain. To measure PPG, we employ an energy-efficient and safe switched-capacitor-based (SC) light emitting diode (LED) driver to illuminate an LED with milliampere-level current pulses. A SC integrator-based AFE converts the current of photodiode with a programmable transimpedance gain. A resistor-based Wheatstone Bridge (WhB) temperature sensor followed by an instrumentation amplifier (IA) provides 27-47 °C sensing range with 0.02 °C inaccuracy. Recorded physiological signals are sequentially sampled and quantized by a 10-bit analog-to-digital converter (ADC) with the successive approximation register (SAR) architecture. The SAR ADC features an energy-efficient switching scheme and achieves a 57.5 dB signal-to-noise-and-distortion ratio (SNDR) within 1 kHz bandwidth. Then, a back data telemetry transmits the baseband data via a backscatter scheme with intermediate-frequency assistance. The ASIC's overall functionality and performance has been evaluated through an invivo experiment.

Curcumin nanoparticles in heat stroke management

ObjectiveThe exacerbation of extreme high-temperature events due to global climate change poses a significant challenge to public health, particularly impacting the central nervous system through heat stroke. This study aims to develop Poly(amidoamine) (PAMAM) nanoparticles loaded with curcumin (PAMAM@Cur) to enhance its therapeutic efficacy in hypothalamic neural damage in a heat stroke model and explore its potential mechanisms.MethodsCurcumin (Cur) was encapsulated into PAMAM nanoparticles through a hydrophobic interaction method, and various techniques were employed to characterize their physicochemical properties. A heat stroke mouse model was established to monitor body temperature and serum biochemical parameters, conduct behavioral assessments, histological examinations, and biochemical analyses. Transcriptomic and proteomic analyses were performed to investigate the therapeutic mechanisms of PAMAM@Cur, validated in an N2a cell model.ResultsPAMAM@Cur demonstrated good stability, photostability, cell compatibility, significant blood–brain barrier (BBB) penetration capability, and effective accumulation in the brain. PAMAM@Cur markedly improved behavioral performance and neural cell structural integrity in heat stroke mice, alleviated inflammatory responses, with superior therapeutic effects compared to Cur or PAMAM alone. Multi-omics analysis revealed that PAMAM@Cur regulated antioxidant defense genes and iron death-related genes, particularly upregulating the PCBP2 protein, stabilizing SLC7A11 and GPX4 mRNA, and reducing iron-dependent cell death.ConclusionBy enhancing the drug delivery properties of Cur and modulating molecular pathways relevant to disease treatment, PAMAM@Cur significantly enhances the therapeutic effects against hypothalamic neural damage induced by heat stroke, showcasing the potential of nanotechnology in improving traditional drug efficacy and providing new strategies for future clinical applications.SignificanceThis study highlights the outlook of nanotechnology in treating neurological disorders caused by heat stroke, offering a novel therapeutic approach with potential clinical applications.Graphical abstract

Predicting Neutropenic Sepsis in Patients with Hematologic Malignancy: A Retrospective Case-Control Study.

Neutropenic sepsis (NS) is one of the leading causes of death among patients with hematologic malignancies. Identifying its predictive factors is fundamental for early detection. Few studies have evaluated the predictive factors in relation to microbial infection confirmation, which is clinically important for initiating sepsis treatment. This study aimed to determine whether selected biomarkers (i.e., body temperature, C-reactive protein, albumin, procalcitonin), treatment-related characteristics (i.e., diagnosis, duration of neutropenia, treatment modality), and infection-related characteristics (i.e., infection source, causative organisms) can predict NS in patients with hematologic malignancies. We also aimed to identify the optimal predictive cutoff points for these parameters. This retrospective case-control study used the data from a total of 163 patients (58 in the sepsis group and 105 in the non-sepsis group). We collected data with reference to the day of specimen collection, with which microbial infection was confirmed. Multiple logistic regression was used to determine predictive risk factors and the area under the curve (AUC) of the receiver operating characteristic for the optimal predictive cutoff points. The independent predictors of NS were average body temperature during a fever episode and procalcitonin level. The odds for NS rose by 9.97 times with every 1°C rise in average body temperature (95% confidence interval, CI [1.33, 75.05]) and by 2.09 times with every 1 ng/mL rise in the procalcitonin level (95% CI [1.08, 4.04]). Average body temperature (AUC = 0.77, 95% CI [0.68, 0.87]) and procalcitonin levels (AUC = 0.71, 95% CI [0.59, 0.84]) have fair accuracy for predicting NS, with the optimal cutoff points of 37.9°C and 0.55 ng/mL, respectively. This study found that average body temperature during a fever episode and procalcitonin are useful in predicting NS. Thus, nurses should carefully monitor body temperature and procalcitonin levels in patients with hematologic malignancies to detect the onset of NS.

Core body temperature estimation model with thermal contact resistance compensation

Continuous and accurate monitoring of core body temperature (CBT) is crucial for personal healthcare, clinical disease diagnosis, and enhancing athletic performance. Current CBT measurement methods typically ignore contact interface variation at the sensor-body interface, resulting in insufficient CBT measurement accuracy under daily wearable scenarios with varying sensor contact pressure. This study proposed a core temperature estimation model with thermal contact resistance (TCR) compensation, introducing the TCR factor into the computational equation to improve estimation accuracy in daily wearable scenarios. A numerical simulation of the temperature field between the human forehead and sensor was developed for model performance evaluation. Given the inconvenience of TCR measurement, this study proposed a method based on pressure/optical photoplethysmography (PPG) signals for updating thermal contact resistance. The mean absolute error of CBTER model under varying thermal contact resistance conditions was 0.26 °C, which was 27 % compared to traditional model errors in simulation. Using pressure updating methods, the result of human trials was 0.01±0.23 °C (with 95 % limits of agreement). Overall, the proposed method effectively compensated for errors in core body temperature estimation due to thermal contact resistance, holding potential for continuous core body temperature monitoring to meet healthcare needs scenarios.

Simulation and Construction of Wireless Heartbeat and Body Temperature Monitoring Device Using Microcontroller

Simulation and Construction of Wireless Heartbeat and Body Temperature Monitoring Device Using Microcontroller

The simulation of wireless body temperature monitoring system based on Internet of Things

Traditional body temperature monitoring technology has some problems, such as inaccurate manual reading, unable to monitor continuously for a long time, and difficult data storage and analysis. To solve these problems, this paper designs an application scenario of Internet of Things in body temperature monitoring, which integrates Internet of Things, network communication, network programming and other technologies, designs the overall architecture, topology structure and IP address allocation scheme of the system, and realizes real-time acquisition, transmission, storage, analysis, and display functions based on the Packet Tracer simulation platform. The performance evaluation and optimization are also carried out. The system realizes wireless monitoring and analysis of the body temperature data collected by the temperature sensor through the home gateway and single chip microcomputer and other devices. After testing, the designed system is stable, which provides a solution for the application of Internet of Things in body temperature monitoring.

The development and characterisation of 3D-printed multi-material thermistor

This paper introduces a multi-material, low-cost, and highly sensitive thermistor concept developed for body temperature monitoring. The designed thermistor utilises poly(3,4-ethylenedioxythophene):poly(4-styrenesulfonate) (PEDOT:PSS) for the temperature sensing layer, silver (Ag) for the contact electrodes, and polycarbonate (PC) as the substrate. In contrast to traditional printed electronics substrates used in thermistor development, the utilisation of Material Extrusion via Fused Deposition Modelling (FDM) for the manufacture of PC substrates is the distinct feature of the work. For the manufacture of multi-material thermistors, two different Additive Manufacturing (AM) methods, FDM for substrates and micro dispensing for PEDOT:PSS sensing layer and Ag electrodes, were employed. Two thermistors with varying sensing areas, namely D1 and D2, were designed and fabricated. The thermistors demonstrated a high degree of linearity and repeatability within the temperature range of 25–45°C with a viable hysteresis maximum around 3 %. The measurement sensitivity of thermistors was assessed based on Temperature Coefficient of Resistance (TCR) values, which were –0.68 ±0.057 % and –0.49 ±0.078 % per °C for the D1 design and –0.53 ±0.078 % and –0.40 ±0.069 % per °C for the D2 design, during heating and cooling, respectively. Comparable average response and recovery times to those reported in the literature were also acquired, which were 31.47 ±1.02 and 54.42 ±0.70 seconds for the D1 design and 27.38 ±0.96 and 48.45 ±1.69 seconds for the D2 design, during heating and cooling, respectively. It was evident that the sensing area had an impact on thermistor TCR as well as response and recovery times, where higher TCR and faster response and recovery times were recorded with the small sensing area. It was also observed that humidity had a significant impact on thermistor reliability, exhibiting a normalised resistance change of ∼12 % and ∼9 % of the initial measurement at 50 % and 75 % RH, respectively. When compared to PEDOT:PSS-based thermistors reported in the literature, the obtained results in this research have demonstrated that our multi-material thermistor concept is a promising candidate for the low-cost and highly sensitive multi-material thermistor that can be manufactured in a fully additive manner using AM technologies.