Sensor Patch Research Articles

An Aptamer-responsive Microneedle Patch Sensor Platform Combining with Hybridization Chain Reaction Amplification for Detection of Steroid Hormone Cortisol in Skin Interstitial Fluid

An Aptamer-responsive Microneedle Patch Sensor Platform Combining with Hybridization Chain Reaction Amplification for Detection of Steroid Hormone Cortisol in Skin Interstitial Fluid

Automated Fabrication of Smart Strain Sensing Threads.

With favorable properties of stretchability, stitchability, and potential to be woven into a fabric, thread-based sensors have gained considerable interest for wearable devices for smart and connected health applications. To facilitate wearable applications, an easy and reliable way to fabricate these thread-based sensors with good performance and consistency is the key while manufacturing these smart threads. In this paper, we propose an automated thread-coating system that can fabricate thread-based strain sensors with controlled parameters. The platform uses integrated sensors for controlled manufacturing of the threads in a highly compact structure that consists of an innovative tension sensor and a closed-loop thermal management system. Using this new system, a sample thread with a gauge factor of 1.47 and tension sensitivity of 32.64 KΩ/N is prepared. Compared with hand-coated thread, the machine-fabricated thread shows much better sensitivity and consistency. The prepared strain sensor is made into a respiration sensor patch and a limb motion patch to demonstrate its application.

Single-atom materials boosting wearable orthogonal uric acid detection

Uric acid (UA) is a vital biomarker for the diagnosis and management of various health conditions, including cardiovascular diseases, gout, kidney disorders, metabolic syndrome, and wound healing. Despite significant advances in wearable sensor technology, challenges persist in developing wearable sensors that are capable of maintaining high sensitivity, selectivity, and stability. In this study, we present an epidermal sensing platform enhanced with single-atom materials (SAMs) designed for flexible and orthogonal electrochemical detection of UA. We designed and synthesized an SAM with Fe-N5 active sites to boost the electrochemical sensing signals, integrating it with laser-engraved graphene (LEG) to fabricate a wearable SAM-based UA patch sensor. This design provides superior UA detection performance compared to sensors based on conventional nanomaterials. In addition, we enhanced the detection accuracy and range by using an orthogonal approach that combines direct oxidation through differential pulse voltammetry (DPV) along with parallel biocatalytic amperometric detection. The resulting SAM-based UA orthogonal sensor patch demonstrated exceptional performance in wearable applications through tests measuring sweat UA levels in subjects before and after consuming a purine-rich diet.Graphical

Flexible, Electrochemical Skin-Like Platform for Inflammatory Biomarker Monitoring.

Addressing global challenges in wound management has greatly encouraged the emergence of home diagnosis and monitoring devices. This technological shift has accelerated the development of new skin patch sensors for continuous health monitoring. A key requirement is the creation of flexible platforms capable of mimicking human skin features. Here, for the first time, an innovative, highly adaptable electrochemical biosensor with molecularly imprinted polymers (MIPs) is customized for the detection of the inflammatory biomarker interleukin-6 (IL-6). The 3-electrode gold pattern is geometrically standardized onto a 6µm thick polyimide flexible membrane, an optically transparent, and biocompatible polymeric substrate. Subsequently, a biomimetic sensing layer specifically designed for the detection of IL-6 target is produced on these transducers. The obtained MIP biosensor shows a good linear response within the concentration range 50pgmL-1-50ngmL-1, with a low limit of detection (8pgmL-1). X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations confirm the modifications of the flexible gold transducer. After optimization, the biosensing device shows remarkable potential in terms of sensitivity, selectivity, and reproducibility. Overall, the integration of a low-cost electrochemical sensor on biocompatible flexible polymers opens the way for a new generation of monitoring tools with higher accuracy, less invasiveness, and greater patient comfort.

An IoT-based contactless neonatal respiratory monitoring system for neonatal care assistance in postpartum center

According to previous studies, one of the major causes of 20 % to 25 % of neonatal deaths is respiratory distress syndrome (RDS). Early identification, progressive monitoring, and treatment and/or management of neonatal RDS can substantially increase the rate of survival in neonates. However, global research indicates frequent shortages and burnout among nursing staff, especially in postpartum units, contributing to the difficulty in early identification of RDS in neonates. Clinicians currently use breathing sounds and frequency as key criteria in the Neonatal Resuscitation Program (NRP) for identifying and treating RDS. In practice, the monitoring of respiratory signal abnormalities relies on sensor patches, which frequently detach from the neonates’ slippery skin, leading to potential skin injuries and unstable signal reception. This paper presents an Internet of Things (IoT)-based contactless neonatal respiratory monitoring system that integrates computer vision (CV), beamforming microphone array (BFMA), and millimeter Wave (mmWave) radar, all connected to a cloud platform. Clinical trials revealed that CV-based neonatal feature identification achieved over 96 % accuracy within 40 cm to 120 cm. The neonatal breathing sound strengthening, utilized CV and BFMA, achieved an average sound-to-noise ratio (SNR) of 5.07 dB, and CV with mmWave radar reduced chest displacement signal error from 0.66 to 0.26 BPM. Additionally, survey results showed that doctors and clinical personnel were satisfied with the system's functionality and usability. This demonstrates the system's ability to assist in monitoring respiratory signals of swaddled neonates and in the early identification of neonatal RDS, with further applications in neonatal care at postpartum centers.

Magnetic Porous Hydrogel-Enhanced Wearable Patch Sensor for Sweat Zinc Ion Monitoring.

Wearable sensors for sweat trace metal monitoring have the challenges of effective sweat collection and the real-time recording of detection signals. The existing detection technologies are implemented by generating enough sweat through exercise, which makes detecting trace metals in sweat cumbersome. Generally, it takes around 20 min to obtain enough sweat, resulting in dallied and prolonged detection signals that cannot reflect the endogenous fluctuations of the body. To solve these problems, we prepared a multifunctional hydrogel as an electrolyte and combined it with a flexible patch electrode to realize real-time monitoring of sweat Zn2+. Such hydrogel has magnetic and porous properties, and the porous structure of hydrogel enables a fast absorption of sweat, and the magnetic property of the addition of fabricated Fe3O4 NPs not only improves the conductivity but also ensures the adjustable internal structures of the hydrogel. Such a sensing platform for sweat Zn2+ monitoring shows a satisfied linear relationship in the concentration range of 0.16-16 µg/mL via differential pulsed anodic striping voltammetry (DPASV) and successfully detects the sweat Zn2+ of four volunteers during exercise and resting, displaying a promising path for commercial application.

Fully integrated sensor array for additives, permittivity, and pH monitoring for fishery

Additive abuse in fishery, such as tricaine methanesulfonate (MS222), ciprofloxacin (CPFX), and malachite green (MG), threatens public human health and interferes with the ecological equilibrium of water resources. However, the majority of the present detection methods suffer from high costs, complex operations, and poor portability. Therefore, real-time and rapid detection of the above additive by mobile devices is becoming increasingly important. Here we report the fabrication and performance of an entirely electrochemical system with USB-stick size for simultaneous detection of MS222, CPFX, and MG, as well as pH and permittivity. The limits of detections are 0.17, 0.67, and 0.28 µg/mL, while the resolution ratios are 10 %, 10 %, and 5 % for MS222, MG, and CPFX, respectively. For both pH and permittivity, they have linear regressions measured by brightness and capacitance of the sample respectively, at the range of 1.5–9 (pH) and 10–20 (permittivity). The interference experiments, using target analytes (40 μg/mL) and 15 interfering analytes (80 μg/mL), demonstrated the anti-interference performance of the sensor patches. The field studies on carps, catfishes, and chubs indicated that the developed integrated portable system could be used for real sample analysis with high performance.

Concept and Implementation of a Novel Continuous Glucose Monitoring Solution With Glucose Predictions on Board.

The recently CE-marked continuous real-time glucose monitoring (rtCGM) solution Accu-Chek® (AC) SmartGuide Solution was developed to enable people with diabetes mellitus (DM) to proactively control their glucose levels using predictive technologies. The comprehensive solution consists of three components that harmonize well with each other. The CGM device is composed of a sensor applicator and a glucose sensor patch whose data are transferred to the connected smartphone by Bluetooth® Low Energy. The user interface of the CGM solution is powered by the AC SmartGuide app delivering current and past glucose metrics, and the AC SmartGuide Predict app providing a glucose prediction suite enabled by artificial intelligence (AI). This article describes the innovative CGM solution.

A wearable sensor patch for joule-heating sweating and comfortable biofluid monitoring

Extracting sufficient volumes of sweat consistently in various scenarios is necessary for next-generation wearable sweat sensors. Here, we developed a sensor patch for Joule-heating sweating and comfortable biofluid monitoring. The Ti3C2Tx nanosheet provides silk fabrics with good electrical conductivity which can serve as an efficient low-voltage electrothermal platform. This biosensor can induce significant sweating in volunteers within just 5 minutes through mild heat stimulation, allowing real-time assessment of metabolic syndrome risks, including Na+, K+, pH, and uric acid levels. Unlike traditional sweat sensors that rely on iontophoresis or physical movement, our approach offered enhanced comfort and efficiency, particularly in sedentary scenarios. Such integration of Joule-heating sweating and sweat analysis endows its potential as a versatile and user-friendly tool in precision medicine and healthcare monitoring.

Ultrastable piezoelectric biomaterial nanofibers and fabrics as an implantable and conformal electromechanical sensor patch.

Poly(l-lactic acid) (PLLA) is a widely used U.S. Food and Drug Administration-approved implantable biomaterial that also possesses strong piezoelectricity. However, the intrinsically low stability of its high-energy piezoelectric β phase and random domain orientations associated with current synthesis approaches remain a critical roadblock to practical applications. Here, we report an interfacial anchoring strategy for fabricating core/shell PLLA/glycine (Gly) nanofibers (NFs) by electrospinning, which show a high ratio of piezoelectric β phase and excellent orientation alignment. The self-assembled core/shell structure offers strong intermolecular interactions between the -OH groups on Gly and C=O groups on PLLA, which promotes the crystallization of oriented PLLA polymer chains and stabilizes the β phase structure. As-received core/shell NFs exhibit substantially enhanced piezoelectric performance and excellent stability. An all NF-based nonwoven fabric is fabricated and assembled as a flexible nanogenerator. The device offers excellent conformality to heavily wrinkled surfaces and thus can precisely detect complex physiological motions often found from biological organs.

Directionally Exfoliated Ni/Co Hydroxide-Organic Framework Nanosheets for Enhanced Wearable Glucose Sensing.

We report two-dimensional (2D) Ni/Co-based metal hydroxide-organic framework nanosheets (Ni/Co-MHOF NSs) for the construction of an efficient electrochemical nonenzymatic glucose sensor. The nanosheet architecture maximizes the exposure of coordinatively unsaturated metal sites, which enables a largely improved electrocatalytic performance toward the glucose oxidation reaction. The as-designed nonenzymatic sensor exhibits a high sensitivity of 235.71 μA·mM-1·cm-2 and a wide linear range of 1-3000 μM. The sensor presents excellent selectivity against several potential interferences and a short response time of 3.0 s. Of interest, a high-performance flexible sensor is developed by depositing the Ni/Co-MHOF NSs on screen-printed electrodes, which reveal decent bending stability. The designed glucose sensor patch can attach to the human body and realize noninvasive glucose monitoring in human sweat. This work may shed light on the application of novel MHOFs in the field of wearable electrochemical sensing.

A wearable microneedle patch incorporating reversible FRET-based hydrogel sensors for continuous glucose monitoring

Continuous glucose monitors are crucial for diabetes management, but invasive sampling, signal drift and frequent calibrations restrict their widespread usage. Microneedle sensors are emerging as a minimally-invasive platform for real-time monitoring of clinical parameters in interstitial fluid. Herein, a painless and flexible microneedle sensing patch is constructed by a mechanically-strong microneedle base and a thin layer of fluorescent hydrogel sensor for on-site, accurate, and continuous glucose monitoring. The Förster resonance energy transfer (FRET)-based hydrogel sensors are fabricated by facile photopolymerizations of acryloylated FRET pairs and glucose-specific phenylboronic acid. The optimized hydrogel sensor enables quantification of glucose with reversibility, high selectivity, and signal stability against photobleaching. Poly (ethylene glycol diacrylate)-co-polyacrylamide hydrogel is utilized as the microneedle base, facilitating effective skin piercing and biofluid extraction. The integrated microneedle sensor patch displays a sensitivity of 0.029 mM−1 in the (patho)physiological range, a low detection limit of 0.193 mM, and a response time of 7.7 min in human serum. Hypoglycemia, euglycemia and hyperglycemia are continuously monitored over 6 h simulated meal and rest activities in a porcine skin model. This microneedle sensor with high transdermal analytical performance offers a powerful tool for continuous diabetes monitoring at point-of-care settings.

Cracks monitoring in reinforced concrete structure with optical fibers patch

In the context of the necessity to monitor civil engineering structures in order to prevent incidents, this paper presents the performance of an innovative optical fibers patch sensor. The patch comprises a tissue containing an optical fiber network. The sensor is attached to the concrete surface and capable of detecting opening cracks in the order of 0.01 mm with good precision, thus satisfying the regulatory limits. The sensor is capable of precisely following the evolution of the crack, including cyclic changes in crack width. The procedure presented in this paper includes a preliminary investigation into the influence of the fibers’ diameter and the density of fibers in the patch, as well as the method of attachment to the concrete’s surface with the objective of identifying an optimal sensor configuration. Subsequently, a series of laboratory tests were conducted on reinforced concrete samples of varying dimensions. Comparisons and verifications of measurements of optical fiber patch sensors are conducted via Digital Image Correlation process. The conclusions of this paper permit the consideration of the use of this novel sensor on and within real reinforced concrete structures.

Wearable skin integrated flexible PVA‐nickel nanocomposite patch for temperature sensor

AbstractThe study focuses on developing a noninvasive, flexible polyvinyl alcohol (PVA)‐nickel (Ni) nanocomposite thin film as a passive skin‐integrated patch sensor for wearable temperature monitoring, marking a significant advancement in the field of wearable sensors. This flexible PVA‐Ni nanocomposite thin film serves as a temperature‐sensitive material, offering several advantages over commercially available active‐type sensors. Field emission scanning electron microscopy (FE‐SEM) images show that Ni nanoparticles (NPs) are broadly dispersed throughout the PVA matrix, indicating the effectiveness of the conductive patch in detecting temperature variations. A PVA‐Ni nanocomposite patch with a thickness of 0.08 mm demonstrated superior flexibility, breathability, and lower tearing strength compared to a pure PVA patch. The film also exhibited excellent repeatability in bending tests, maintaining performance after 120 bending and unloading cycles, suggesting its durability for long‐term use as a wearable sensor. Furthermore, the fabricated sensors function as thermistors, with conductivity increasing linearly with temperature. The performance of these temperature sensors was compared, revealing a highest temperature coefficient of resistance (TCR) and thermal index of −1.08%/°C and 1271 K, respectively. The sensors showed high temperature sensitivity between room temperature and 50°C, outperforming typical commercial platinum temperature sensors. The stability and response time of the PVA‐Ni nanocomposite film were evaluated by adhering the patch to a human wrist and capturing thermal images using a FLIR thermal imaging camera. The observed maximum temperature difference of approximately 1.9–2.1°C highlights the patch's sensitivity in detecting temperature changes. Additionally, the antimicrobial properties of the conductive film were tested to assess its biocompatibility, confirming its potential for applications in energy storage, thermal management, and early breast cancer detection.

A Fully Self‐Healing Patch of Integrated Bio‐Signal Monitoring Sensors with Self‐Healing Microporous Foam and Au Nanosheet Electrodes

AbstractA fully self‐healing sensor patch consisting of an in‐plane integrated dual‐mode sensor and a pressure sensor with a vertically integrated electrocardiogram (ECG) electrode is reported. For a full‐device self‐healing, interlayer self‐bonding by using self‐healing oxime‐carbamate bond‐based polyurethane and room temperature self‐healing TUEG3 capped Au nanosheet (T‐Au NS) electrodes are devised. Via the use of a self‐healing sensor foam prepared by a coating of a self‐healing composite of polyurethane and polyaniline onto a microporous graphene foam, a self‐healing dual‐mode sensor is fabricated to detect the pressure and temperature simultaneously without interference. Furthermore, the interdigitated self‐healing electrode of T‐Au NS is applied to the pressure sensor to enhance the sensitivity up to 208.62 kPa−1 (<1 kPa), enabling the detection of small pulse signals even after multiple self‐healing events. By using the common self‐healing T‐Au NS electrode vertically integrated onto the sensor patch, ECG signals are also detected. With this sensor patch, skin temperature, wrist pulse, and ECG signals are successfully detected after a simultaneous full‐device self‐healing from complete bisection. This study demonstrates the facile fabrication of a high‐performance, fully self‐healing patch of multi‐sensors via the deliberate selection of sensor design and the associated functional materials, confirming its high potential applicability to highly durable health monitoring systems.

Intradermal Lactate Monitoring Based on a Microneedle Sensor Patch for Enhanced In Vivo Accuracy.

Lactate is an important diagnostic and prognostic biomarker of several human pathological conditions, such as sepsis, malaria, and dengue fever. Unfortunately, due to the lack of reliable analytical decentralized platforms, the determination of lactate yet relies on discrete blood-based assays, which are invasive and inefficient and may cause tension and pain in the patient. Herein, we demonstrate the potential of a fully integrated microneedle (MN) sensing system for the minimally invasive transdermal detection of lactate in an interstitial fluid (ISF). The originality of this analytical technology relies on: (i) a strategy to provide a uniform coating of a doped polymer-based membrane as a diffusion-limiting layer on the MN structure, optimized to perform full-range lactate detection in the ISF (linear range of response: 0.25-35 mM, 30 s assay time, 8 h operation), (ii) double validation of ex vivo and in vivo results based on ISF and blood measurements in rats, (iii) monitoring of lactate level fluctuations under the administration of anesthesia to mimic bedside clinical scenarios, and (iv) in-house design and fabrication of a fully integrated and portable sensing device in the form of a wearable patch including a custom application and user-friendly interface in a smartphone for the rapid, routine, continuous, and real-time lactate monitoring. The main analytical merits of the lactate MN sensor include appropriate selectivity, reversibility, stability, and durability by using a two-electrode amperometric readout. The ex-vivo testing of the MN patch of preconditioned rat skin pieces and euthanized rats successfully demonstrated the accuracy in measuring lactate levels. The in vivo measurements suggested the existence of a positive correlation between ISF and blood lactate when a lag time of 10 min is considered (Pearson's coefficient = 0.85, mean difference = 0.08 mM). The developed MN-based platform offers distinct advantages over noncontinuous blood sampling in a wide range of contexts, especially where access to laboratory services is limited or blood sampling is not suitable. Implementation of the wearable patch in healthcare could envision personalized medicine in a variety of clinical settings.

E-cardiac patch to sense and repair infarcted myocardium

Conductive cardiac patches can rebuild the electroactive microenvironment for the infarcted myocardium but their repair effects benefit by carried seed cells or drugs. The key to success is the effective integration of electrical stimulation with the microenvironment created by conductive cardiac patches. Besides, due to the concerns in a high re-admission ratio of heart patients, a remote medicine device will underpin the successful repair. Herein, we report a miniature self-powered biomimetic trinity triboelectric nanogenerator with a unique double-spacer structure that unifies energy harvesting, therapeutics, and diagnosis in one cardiac patch. Trinity triboelectric nanogenerator conductive cardiac patches improve the electroactivity of the infarcted heart and can also wirelessly monitor electrocardiosignal to a mobile device for diagnosis. RNA sequencing analysis from rat hearts reveals that this trinity cardiac patches mainly regulates cardiac muscle contraction-, energy metabolism-, and vascular regulation-related mRNA expressions in vivo. The research is spawning a device that truly integrates an electrical stimulation of a functional heart patch and self-powered e-care remote diagnostic sensor.

Oxide semiconductor based deep‐subthreshold operated read‐out electronics for all‐printed smart sensor patches

AbstractThe ability to fabricate an entire smart sensor patch with read‐out electronics using commercial printing techniques may have a wide range of potential applications. Although solution‐processed oxide thin film transistors (TFTs) are capable of providing high mobility electron transport, resulting in large ON‐state current and power output, there is hardly any literature report that uses the printed oxide TFTs at the sensor interfaces. Here, printed amorphous indium‐gallium‐zinc oxide (a‐IGZO)‐based deep‐subthreshold operated TFTs that comprise signal amplifiers and analog‐to‐digital converters (ADCs) that can successfully digitalize the analog sensor signals up to a frequency range of 1 kHz are reported. In addition, exploiting the high current oxide TFTs, a current drive circuit placed after the ADC unit has been found useful in producing easy‐to‐detect visual recognition of the sensor signal at a predefined threshold crossover. Notably, the entire smart sensor patch is demonstrated to operate at a low supply voltage of ≤2 V, thereby ensuring that it can be an on‐chip energy source compatible and standalone detection unit.

A laser-Engraved Wearable Electrochemical Sensing Patch for Heat Stress Precise Individual Management of Horse.

In point-of-care diagnostics, the continuous monitoring of sweat constituents provides a window into individual's physiological state. For species like horses, with abundant sweat glands, sweat composition can serve as an early health indicator. Considering the salience of such metrics in the domain of high-value animal breeding, a sophisticated wearable sensor patch tailored is introduced for the dynamic assessment of equine sweat, offering insights into pH, potassium ion (K+), and temperature profiles during episodes of heat stress and under normal physiological conditions. The device integrates a laser-engraved graphene (LEG)sensing electrode array, a non-invasive iontophoretic module for stimulated sweat secretion, an adaptable signal processing unit, and an embedded wireless communication framework. Profiting from an admirable Truth Table capable of logical evaluation, the integrated system enabled the early and timely assessment for heat stress, with high accuracy, stability, and reproducibility. The sensor patch has been calibrated to align with the unique dermal and physiological contours of equine anatomy, thereby augmenting its applicability in practical settings. This real-time analysis tool for equine perspiration stands to revolutionize personalized health management approaches for high-value animals, marking a significant stride in the integration of smart technologies within the agricultural sector.

An examination of wearable technology in the field biomedical engineering: A review

A wearable device is a piece of technology that can be worn on the body, designed to be portable, lightweight and equipped with various sensors or features for specific functions. As a game-changer in the field of biomedical engineering, wearable technology provides innovative approaches to illness management, individualized healthcare and health monitoring. This review looks at wearable technology as it stands in the field of biomedical engineering, emphasizing its uses, difficulties and potential. The research examines a wide variety of wearable wireless biosensors, sensor patches, wristwatches, wearable face masks and multi-sensor smart clothing, emphasizing their potential to measure physiological parameters, including blood pressure, heart rate and sleep patterns. This study demonstrates the need for intelligent wearable devices for high-quality signal capture, processing and continuous monitoring of critical parameters. The creation of smart wearables that meet the specified design standards enables the creator of a wearable with reduced power consumption that can be used to monitor the health of patients. This study offers a thorough analysis of wearable technology's present state, obstacles and potential applications in the field of biomedical engineering. It will be of great use to investigators, medical professionals and developers of technology.