Wearable Platform Research Articles

Stress Level Assessment by a Multi-Parametric Wearable Platform: Relevance of Different Physiological Signals

Stress Level Assessment by a Multi-Parametric Wearable Platform: Relevance of Different Physiological Signals

Engineering a fluorescent probe for the visual and wearable detection of N2H4 in foods, environment samples and biological imaging

Hydrazine (N2H4), as an important chemical raw material widely used in many fields, caused serious harm to human, food and environment. Therefore, a smart fluorescent probe TPC-N2H4 with intramolecular charge transfer (ICT) process was fabricated for colorimetric and fluorescent differentiating of N2H4 in many samples. When TPC-N2H4 met N2H4, blue emission at 451 nm was obviously observed attributed to the interruption of ICT process, resulting in the formation of the hydrazone structure. Additionally, smartphone-assisted colorimetric and fluorescent sensing platforms had been developed for real-time monitoring of N2H4. Importantly, TPC-N2H4 with low toxicity revealed its ability to image N2H4 in HeLa cells, onion and Arabidopsis thaliana. Interestingly, a hydrogel-coated cotton swab sensor was developed with TPC-N2H4 as recognition unit, which showed obvious color and emission changes after N2H4 fumigation with fast response speed. Flexible fluorescent TPC-N2H4-glove was constructed for wearable N2H4 detection and used to monitor N2H4 in food and environment samples. In brief, the TPC-N2H4 probe not only showed great potential in N2H4 detection for environmental and food safety, but also provided a new method for wearable tracking platforms in toxic substance detection.

Pasteables: A Flexible and Smart “Stick-and-Peel” Wearable Platform for Fitness and Athletics

Wearable technologies are becoming increasingly popular and transforming our fitness and sports industry. Monitoring health parameters and body activity can help achieve fitness goals, improve sports performance, and aid in physiotherapy. However, state-of-the-art wearable devices are often not flexible, expensive, hard to set up, or have privacy concerns. They are designed and optimized for a specific application with tight hardware-software integration and it is hard or impossible to re-purpose them for diverse use cases. In this paper, we propose a flexible, re-configurable human body movement and health monitoring platform, called "Pasteables". It is a stick-and-peel device (which acts like a band-aid) that attaches to the skin or clothing and can create an on-body network of smart wearables. Given an application, Pasteables can be easily adapted to its requirements while ensuring good performance and privacy. We present the overall architecture, system design steps, and the configuration process. We have designed a set of functional prototypes and configured them for performing a variety of camera-less pose and posture detection tasks, which are important for athletes, professional dancing, physiotherapy, and fitness workouts. We note that the Pasteables can perform pose/posture detection without external stationary reference at low cost and high accuracy.

Active-type piezoelectric smart textiles with antifouling performance for pathogenic control

Recently, an investigation into preventive measures for coronavirus disease 2019 (COVID-19) has garnered considerable attention. Consequently, strategies for the proactive prevention of viral pathogens have also attracted significant interest in the field of wearable devices and electronic textiles research, particularly due to their potential applications in personal protective equipment. In this study, we introduce smart textiles designed with optimized piezoelectric devices that exhibit antifouling performance against microorganisms and actively inactivate viruses. These active-type smart textiles, which incorporate advanced lead zirconate titanate (PZT) ceramics, a stretchable interconnector array, and polymeric fabric, demonstrate effective antifouling capabilities, detaching approximately 90% of Escherichia coli and 75% of SARS-CoV-2. Furthermore, they inactivate viruses, releasing ~26.8 ng of N protein from ruptured SARS-CoV-2, using ultrasonic waves within the wearable platform. Experimental results show that piezoelectric smart textiles significantly reduce the spread of COVID-19 by leveraging the electrical and acoustic properties of PZT ceramics.

LSTM Gate Disclosure as an Embedded AI Methodology for Wearable Fall-Detection Sensors

In this paper, the concept of symmetry is used to design the efficient inference of a fall-detection algorithm for elderly people on embedded processors—that is, there is a symmetric relation between the model’s structure and the memory footprint on the embedded processor. Artificial intelligence (AI) and, more particularly, Long Short-Term Memory (LSTM) neural networks are commonly used in the detection of falls in the elderly population based on acceleration measures. Nevertheless, embedded systems that may be utilized on wearable or wireless sensor networks have a hurdle due to the customarily massive dimensions of those networks. Because of this, the algorithms’ most popular implementation relies on edge or cloud computing, which raises privacy concerns and presents challenges since a lot of data need to be sent via a communication channel. The current work proposes a memory occupancy model for LSTM-type networks to pave the way to more efficient embedded implementations. Also, it offers a sensitivity analysis of the network hyper-parameters through a grid search procedure to refine the LSTM topology network under scrutiny. Lastly, it proposes a new methodology that acts over the quantization granularity for the embedded AI implementation on wearable devices. The extensive simulation results demonstrate the effectiveness and feasibility of the proposed methodology. For the embedded implementation of the LSTM for the fall-detection problem on a wearable platform, one can see that an STM8L low-power processor could support a 40-hidden-cell LSTM network with an accuracy of 96.52%.

Snowmotion A Wearable Sensor-based Mobile Platform For Alpine Skiing Motion Capture And Analysis

Snowmotion A Wearable Sensor-based Mobile Platform For Alpine Skiing Motion Capture And Analysis

Multiwalled Carbon Nanotube-Templated Nickel Porphyrin Covalent Organic Framework for Pencil-Drawn Noninvasive Respiration Sensors.

Paper-integrated configuration with miniaturized functionality represents one of the future main green electronics. In this study, a paper-based respiration sensor was prepared using a multiwalled carbon nanotube-templated nickel porphyrin covalent organic framework (MWCNTs@COFNiP-Ph) as an electrical identification component and pencil-drawn graphite electric circuits as interdigitated electrodes (IDEs). The MWCNTs@COFNiP-Ph not only inherited the high gas sensing performance of porphyrin and the aperture induction effect of COFs but also overcame the shielding effect between phases through the MWCNT template. Furthermore, it possessed highly exposed M-N4 metallic active sites and unique periodic porosity, thereby effectively addressing the key technical issue of room-temperature sensing for the respiration sensor. Meanwhile, the introduction of a pencil-drawing approach on common printing papers facilitates the inexpensive and simple manufacturing of the as-fabricated graphite IDE. Based on the above advantages, the MWCNTs@COFNiP-Ph respiration sensor had the characteristics of wide detection range (1-500 ppm), low detection limit (30 ppb), acceptable flexibility for toluene, and rapid response/recovery time (32 s/116 s). These advancements facilitated the integration of the respiration sensor into surgical masks and clothes with maximum functionality at a minimized size and weight. Moreover, the primary internal mechanism of COFNiP-Ph for this efficient toluene detection was investigated through in situ FTIR spectra, thereby directly elucidating that the chemisorption interaction of oxygen modulated the depletion layers, resulting in alterations in sensor resistance upon exposure to the target gas. The encouraging results revealed the feasibility of employing a paper-sensing system as a wearable platform in green electronics.

A Passive Perspiration Inspired Wearable Platform for Continuous Glucose Monitoring.

The demand for glucose monitoring devices has witnessed continuous growth from the rising diabetic population. The traditional approach of blood glucose (BG) sensor strip testing generates only intermittent glucose readings. Interstitial fluid-based devices measure glucose dynamically, but their sensing approaches remain either minimally invasive or prone to skin irritation. Here, a sweat glucose monitoring system is presented, which completely operates under rest with no sweat stimulation and can generate real-time BG dynamics. Osmotically driven hydrogels, capillary action with paper microfluidics, and self-powered enzymatic biochemical sensor are used for simultaneous sweat extraction, transport, and glucose monitoring, respectively. The osmotic forces facilitate greater flux inflow and minimize sweat rate fluctuations compared to natural perspiration-based sampling. The epidermal platform is tested on fingertip and forearm under varying physiological conditions. Personalized calibration models are developed and validated to obtain real-time BG information from sweat. The estimated BG concentration showed a good correlation with measured BG concentration, with all values lying in the A+B region of consensus error grid (MARD = 10.56% (fingertip) and 13.17% (forearm)). Overall, the successful execution of such osmotically driven continuous BG monitoring system from passive sweat can be a useful addition to the next-generation continuous sweat glucose monitors.

Robust Control of Exo-Abs, a Wearable Platform for Ubiquitous Respiratory Assistance

Abstract Existing noninvasive breathing assist options compatible with out-of-hospital settings are limited and not appropriate to enable essential everyday activities, thereby deteriorating the quality of life. In our prior work, we developed the Exo-Abs, a novel wearable robotic platform for ubiquitous assistance of respiratory functions in patients with respiratory deficiency. This paper concerns the development of a model-based closed-loop control algorithm for the Exo-Abs to automate its breathing assistance. To facilitate model-based development of closed-loop control algorithms, we developed a control-oriented mathematical model of the Exo-Abs. Then, we developed a robust absolutely stabilizing gain-scheduled proportional-integral control algorithm for automating the breathing assistance with the Exo-Abs, by (i) solving a linear matrix inequality formulation of the Lyapunov stability condition against sector-bounded uncertainty and interindividual variability in the mechanics of the abdomen and the lungs and (ii) augmenting it with a heuristic yet effective gain scheduling algorithm. Using in silico evaluation based on realistic and plausible virtual patients, we demonstrated the efficacy and robustness of the automated breathing assistance of the Exo-Abs under a wide range of variability in spontaneous breathing and Exo-Abs efficiency: the absolutely stabilizing gain-scheduled proportional-integral control resulted in small exhalation trajectory tracking error (<30 ml) with smooth actuation, which was superior to (i) its proportional-integral control counterpart in tracking efficacy and to (ii) its proportional-integral-derivative control counterpart in chattering.

Wearable Masks Integrated with Conducting Polymer and Carbon-Based Nanomaterials for VOC and Breath Monitoring

There has been considerable effort to develop wearable electronics from life-supporting devices for solders to fashion accessories such as smartwatches. The research of gas sensors has also attempted to adapt wearables with the power of nanotechnology. On the wearable platform, miniature gas sensors will provide real-time information about the atmosphere to protect each personnel from possible hazardous chemical attacks. In addition, wearable gas sensors can be facilitated to monitor human’s breath as medical applications. [1] Continuous monitoring of respiratory rate in real-time can act as a crucial benchmark for non-invasively detecting cardiac or arterial vascular function. Anomalies in respiratory rate serve as a significant indicator of a patient's health deterioration. Furthermore, it has been reported that aberrations in respiratory rate, as a physiological parameter, can be utilized to monitor common COVID-19 symptoms [2]. The analysis of breath through identifying biomarkers in exhaled breath proves to be an effective method for assessing metabolic disorders or dysfunctions in the human body. Conducting polymers (CPs) have generated significant interest in constructing flexible gas sensors. The inherent issue with pure CPs lies in their tendency to deprotonate in the presence of air, leading to a notable decline in long-term stability. Furthermore, limited gas response on diverse gaseous species demands the exploration of hybridizing CPs and other nanomaterials. When nanomaterials are hybridized with CPs, a synergistic effect, which comes from the benefits of each material, can improve sensing performance.In this study, polyaniline (PANI) conducting polymer and carbon-based nanomaterials, including carbon nanotubes (CNTs), graphene, or MXene were synthesized in a composite form and deposited into disposable masks. The developed gas sensor demonstrates remarkable stability attributed to the presence of van der Waals forces and π–π interactions between carbon-based nanomaterials and polyaniline (PANI). This stability is crucial for its reliable performance over time. The sensor's sensitivity is notably improved due to enhanced charge transfer channels and a porous structure that facilitates the adsorption of target gas. Additionally, the composite sensors detect breathing patterns in real-time, which demonstrates noninvasive human breath monitoring. A noteworthy aspect is that a significant portion of breath signals originates from the presence of target gases and moisture in exhaled breath. Although volatile sulfur compounds, CO2, and volatile organic compounds in the exhaled breath have a minimal influence on the sensing signals, the sensor remains highly responsive to the key components, particularly target gas by selecting carbon-based nanomaterials [3, 4]. The proposed gas sensing mechanism of the CP-based composites is discussed.

Upcycling Compact Disks to Flexible Nanoporous Gold Electrodes for Nitrite Biosensing

Electrochemical biosensors are crucial in disease detection due to their simplicity, rapidity, and sensitivity. As a wearable or e-skin platform, electrochemical sensors are frequently restricted by gradual degradation, complexity, limited active surface area, arduous fabrication process, and high cost. Therefore, soft electrochemical biosensors that are mechanically biocompatible, easy to prototype, and robust for sensitive biosensing are highly sought. To mitigate such an issue, recordable compact disks (CDs) have been upcycled to advanced biosensors exhibiting flexible and disposable and being applicable to various biomedical applications, making them an economical and practical option. However, the limited surface area of the gold CDs electrode prevents optimal electrochemical catalytic performance. Nanostructure has been widely embedded in electrochemical biosensor construction to optimize electrode surface area and the number of active sites, which can contribute to improved detection sensitivity, selectivity, and electron transfer.Here, we aim to develop an advanced nanoporous gold film electrode (NPGFE) from CD for a simple, flexible, sensitive, and larger surface area electrode with reproducible areas. The fabrication and modification of gold CDs film were accomplished through two steps: 1) A mechanical cutter tailored the gold film after being transferred from CDs into a flexible substrate (Polyimide tape). Before placing the CDs film between the two laminating sheets, an aperture (1 mm diameter) was made in one of the laminating sheets to expose the tailored gold film electrode (GFE) and insulate the undesired area using a thermal laminator to ensure an adequate seal as a simple and low-cost approach; 2) The nanoporous gold (NPG) was electrochemically deposited onto the gold CDs film surface in gold (III) chloride trihydrate (HAuCl4·3H2O) and ammonium chloride (NH4Cl) solution at a potential of -4V for 100 s. Surface morphology characteristics and elemental analyses were investigated using scanning electron microscopy, while electrochemical studies were carried out in the CH Instruments potentiostat.The SEM images confirm a homogeneous distribution of NPG across the electrode’s surface. The energy-dispersive X-ray analyses exhibited the purity of the deposited NPG. The effective surface area was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M KCl and 1 mM K3[Fe(CN)6] solution. From the slope of the Ip vs. v1/2 plot and the Randles-Sevcik equation, the active surface area of the NPGFE was significantly increased compared to the unmodified GFE. EIS was conducted to evaluate electron transfer resistance and obtain the semicircular diameter in Nyquist plots. In comparison to the unmodified GFE, the NPGFE showed a semicircle with a smaller diameter, indicating that the electron transfer resistance is minimized. The electrochemical characterization of the NPGFE was investigated by CV and amperometric techniques in 0.1 M PBS solution at ambient temperature (25°C) and pH 7.4. The NPGFE performance was studied at a fixed potential (0.77 V vs. Ag/AgCl) by analyzing the current response upon adding nitrite and anodic peak current at a potential range from 0.3 to 0.9 V (vs. Ag/AgCl). The calibration curve plot was linear over 0.5 μM to 9 mM with 20 nA·μM−1·cm−2 sensitivity and a low detection limit of 0.5 μM with a correlation coefficient (R2) of 0.99. The NPGFE's reproducibility reusability studies were conducted to evaluate electrode stability when prepared independently and utilized repeatedly under the same condition. Results demonstrate remarkable reproducibility and highly satisfactory reusability, making it suitable for practical application. The effect of pH on nitrite detection was investigated at different pH values. The anodic peak currents decreased and shifted to the low potential when the pH was increased from 5.0 to 10.0, indicating that protons were directly involved in the nitrite redox reaction. Also, the selectivity studies showed a significant increase in the current response when nitrite, ascorbic acid, and sodium sulfite were introduced to the solution, and there were no remarkable changes when other interferents were added. The long-term stability results showed that the NPGFE retains 99% of its initial current response to NO2 - after six months of storage, indicating satisfactory stability and long service life of NPGFE. Importantly, the sensing performance while stretching the NPGFE will be investigated to produce biocompatible relevant results.The flexible, nanoporous upcycled CDs electrode utilizing craft machines provide fast prototyping electrochemical biosensors for skin-interfaced bioelectronics. The nanoporous CD-based biosensor significantly improves electrocatalytic performance toward nitrite detection along with exceptional improvements in the cost-effective and sustainable fabrication process for flexible electronics. Future work relies on developing system-integrated biosensors based on systematic reliability and feasibility tests. Soft upcycled bioelectronics holds significant potential in advancing biomedical in situ real-time analysis in various platforms of flexible and nanostructured biosensors. Figure 1

Advancing Wearable Cardiovascular Monitoring: Integration of Flexible Piezoresistive Sensors for Robust Pulse Waveform Detection

Wearable, flexible piezoresistive pressure sensors have diverse applications, spanning electronic skin, robotic limbs, and cardiovascular monitoring. Recent advancements in wearable health monitoring devices utilizing these sensors show promise for continuous cardiovascular monitoring. However, a substantial gap exists between laboratory development and market availability for pressure sensor based pulse monitoring. Challenges include the lack of effective testing schemes ensuring robust wearable operation and the necessity of bulky signal acquisition equipment, limiting adaptability. This study addresses these challenges by integrating the outputs of multiple flexible, skin-mountable piezoresistive sensors to create a robust wearable platform. This platform encompasses both sensing and miniaturized signal acquisition for arterial pulse waveform monitoring. The single piezoresistive sensor in our design exhibits sensitivity (1.4 kPa-1 at 2 – 8 kPa). This robust signal allows for the use of simple, compact signal collection devices mounted on a wristband. Moreover, the capability of the the system allows for detection of the three distinct peaks associated with the full pulse waveform, including the systolic, diastolic, and reflected diastolic peaks. In validation, a comparison between the wrist pulse waveform obtained with the compact signal collection device and a standard sourcemeter (Keithley 2460) confirms the capability of our wearable system to resolve the three distinct peaks. This work contributes to bridging the gap between research and practical applications, offering a potential solution for widespread adoption of continuous cardiovascular monitoring technology in diverse settings.

WSe2/chitosan-based wearable multi-functional platform for monitoring electrophysiological signals, pulse rate, respiratory rate, and body movements.

Acleanroom free optimized fabrication of a low-cost facile tungsten diselenide (WSe2) combined with chitosan-based hydrogel device is reportedfor multifunctional applications including tactile sensing, pulse rate monitoring, respiratory rate monitoring, human body movements detection, and human electrophysiological signal detection. Chitosan being a natural biodegradable, non-toxic compound serves as a substrate to the semiconducting WSe2 electrode which is synthesized using a single step hydrothermal technique. Elaborate characterization studies are performed to confirm the morphological, structural, and electrical properties of the fabricated chitosan/WSe2 device. Chitosan/WSe2 sensor with copper contacts on each side is put directly on skin to capture human body motions. The resistivity of the sample was calculated as 26 kΩ m-1. The device behaves as an ultrasensitive pressure sensor for tactile and arterial pulse sensing with response time of 0.9s and sensitivity of around 0.02kPa-1. It is also capable for strain sensing with a gauge factor of 54 which is significantly higher than similar other reported electrodes. The human body movements sensing can be attributed to the piezoresistive character of WSe2 that originates from its non-centrosymmetric structure. Further, the sensor is employed for monitoring respiratory rate which measures to 13 counts/min for healthy individual and electrophysiological signals like ECG and EOG which can be used later for detecting numerous pathological conditions in humans. Electrophysiological signal sensing is carried out using a bio-signal amplifier (Bio-Amp EXG Pill) connected to Arduino. The skin-friendly, low toxic WSe2/chitosan dry electrodes pave the way for replacing wet electrodes and find numerous applications in personalized healthcare.

Nerve-Agent Selective Chemiresistors Fabricated by Oxime Decorated Polypyrrole Layer on Cellulose Paper

In continuous research of detecting highly toxic chemical warfare agents to ensure preparedness for the future battlefield, flexible and wearable sensor platforms with high sensitivity are still demanding. Herein we demonstrate a facile fabrication of polypyrrole-based chemiresistors on cellulose paper for the detection of nerve gas simulants. In order to optimize electrical properties of sensor platform, conducting polymer made of polypyrrole were first synthesized on flexible cellulose paper and interdigitated electrodes were formed thereon. Following confirmation of polypyrrole and/or oxime moiety through FT-IR analyses, electrical characteristics were measured in the various ratio of monomers between simple pyrrole and oxime-modified one. Typically for the optimized chemiresistor(2:8 molar ratio of simple pyrrole and oxime-modified one), eleven species of chemical warfare agents were examined and enhanced conductivity(10<sup>4</sup>~10<sup>5</sup> order) was observed for three simulants(diethyl cyanophosphonate, diisopropyl fluorophosphonate and diethyl chlorophosphonate), which was mainly attributed to intermolecular hydrogen bonding, while no significant responses was recorded against sixteen common volatile organic chemicals.

Synergistic Strategies of Biomolecular Transport Technologies in Transdermal Healthcare Systems.

Transdermal healthcare systems have gained significant attention for their painless and convenient drug administration, as well as their ability to detect biomarkers promptly. However, the skin barrier limits the candidates of biomolecules that can be transported, and reliance on simple diffusion poses a bottleneck for personalized diagnosis and treatment. Consequently, recent advancements in transdermal transport technologies have evolved toward active methods based on external energy sources. Multiple combinations of these technologies have also shown promise for increasing therapeutic effectiveness and diagnostic accuracy as delivery efficiency is maximized. Furthermore, wearable healthcare platforms are being developed in diverse aspects for patient convenience, safety, and on-demand treatment. Herein, a comprehensive overview of active transdermal delivery technologies is provided, highlighting the combination-based diagnostics, therapeutics, and theragnostics, along with the latest trends in platform advancements. This offers insights into the potential applications of next-generation wearable transdermal medical devices for personalized autonomous healthcare.

Nature-Inspired Superhydrophilic Biosponge as Structural Beneficial Platform for Sweating Analysis Patch.

Perspiration plays a pivotal role not only in thermoregulation but also in reflecting the body's internal state and its response to external stimuli. The up-to-date skin-based wearable platforms have facilitated the monitoring and simultaneous analysis of sweat, offering valuable physiological insights. Unlike conventional passive sweating, dynamic normal perspiration, which occurs during various activities and rest periods, necessitates a more reliable method of collection to accurately capture its real-time fluctuations. An innovative microfluidic patch incorporating a hierarchical superhydrophilic biosponge, poise to significantly improve the efficiency capture of dynamic sweat is introduced. The seamlessly integrated biosponge microchannel showcases exceptional absorption capabilities, efficiently capturing non-sensitive sweat exuding from the skin surface, mitigating sample loss and minimizing sweat volatilization. Furthermore, the incorporation of sweat-rate sensors alongside a suite of functional electrochemical sensors endows the patch of uninterrupted monitoring and analysis of dynamic sweat during various activities, stress events, high-energy intake, and other scenarios.

A MOFs‐Derived Hydroxyl‐Functionalized Hybrid Nanoporous Carbon Incorporated Laser‐Scribed Graphene‐Based Multimodal Skin Patch for Perspiration Analysis and Electrocardiogram Monitoring

AbstractAlthough metal‐organic framework (MOF)‐derived nanoporous C (NPC) materials offer several advantages for electrochemical sensor applications, surface functionalization and porosity tuning can affect sensor performance. This study presents the development of a skin patch for perspiration and electrocardiogram (ECG) monitoring, leveraging the unique properties of MOF‐on‐MOF‐derived surface‐functionalized hybrid nanoporous C (f‐HNPC) incorporated into laser‐scribed graphene (LSG). Hydroxyl (OH) group‐functionalized NPC, achieved through KOH activation, facilitates electron transport at the electrode–electrolyte interface. This enhances the electrochemical activity, thereby improving sensor sensitivity and expanding the detection range. The integration of f‐HNPC provides enhanced surface area and electrochemical properties, enabling sensitive and selective detection of sweat biomarkers, including glucose (103 µA mM−1 cm−2) and uric acid (184 µA mM−1 cm−2) along with an ultra‐wide glucose detection range (up to 41.5 mM). Moreover, the incorporation of LSG ensures excellent mechanical flexibility, facilitating conformal contact with the skin for reliable signal acquisition. The proposed skin patch demonstrates promising performance in real‐time perspiration analysis and ECG monitoring with a signal‐to‐noise ratio of 23.63 dB, along with high stability and long‐term durability. The synergistic combination of f‐HNPC and LSG shows great potential for developing advanced wearable biosensing platforms for personalized healthcare applications.

The Future of Nanotechnology-Driven Electrochemical and Electrical Point-of-Care Devices and Diagnostic Tests.

Point-of-care (POC) devices have become rising stars in the biosensing field, aiming at prognosis and diagnosis of diseases with a positive impact on the patient but also on healthcare and social care systems. Putting the patient at the center of interest requires the implementation of noninvasive technologies for collecting biofluids and the development of wearable platforms with integrated artificial intelligence-based tools for improved analytical accuracy and wireless readout technologies. Many electrical and electrochemical transducer technologies have been proposed for POC-based sensing, but several necessitate further development before being widely deployable. This review focuses on recent innovations in electrochemical and electrical biosensors and their growth opportunities for nanotechnology-driven multidisciplinary approaches. With a focus on analytical aspects to pave the way for future electrical/electrochemical diagnostics tests, current limitations and drawbacks as well as directions for future developments are highlighted.

Assessing the performance of a robust multiparametric wearable patch integrating silicon-based sensors for real-time continuous monitoring of sweat biomarkers

The development of wearable devices for sweat analysis has experienced significant growth in the last two decades, being the main focus the monitoring of athletes health during workouts. One of the main challenges of these approaches has been to attain the continuous monitoring of sweat for time periods over 1 h. This is the main challenge addressed in this work by designing an analytical platform that combines the high performance of potentiometric sensors and a fluidic structure made of a plastic fabric into a multiplexed wearable device. The platform comprises Ion-Sensitive Field-Effect Transistors (ISFETs) manufactured on silicon, a tailor-made solid-state reference electrode, and a temperature sensor integrated into a patch-like polymeric substrate, together with the component that easily collects and drives samples under continuous capillary flow to the sensor areas. ISFET sensors for measuring pH, sodium, and potassium ions were fully characterized in artificial sweat solutions, providing reproducible and stable responses. Then, the real-time and continuous monitoring of the biomarkers in sweat with the wearable platform was assessed by comparing the ISFETs responses recorded during an 85-min continuous exercise session with the concentration values measured using commercial Ion-Selective Electrodes (ISEs) in samples collected at certain times during the session. The developed sensing platform enables the continuous monitoring of biomarkers and facilitates the study of the effects of various real working conditions, such as cycling power and skin temperature, on the target biomarker concentration levels.

Towards a Wearable Feminine Hygiene Platform for Detection of Invasive Fungal Pathogens via Gold Nanoparticle Aggregation.

Candida albicans is an opportunistic fungus that becomes pathogenic and problematic under certain biological conditions. C. albicans may cause painful and uncomfortable symptoms, as well as deaths in immunocompromised patients. Therefore, early detection of C. albicans is essential. However, conventional detection methods are costly, slow, and inaccessible to women in remote or developing areas. To address these concerns, we have developed a wearable and discrete naked-eye detectable colorimetric platform for C. albicans detection. With some modification, this platform is designed to be directly adhered to existing feminine hygiene pads. Our platform is rapid, inexpensive, user-friendly, and disposable and only requires three steps: (i) the addition of vaginal fluid onto sample pads; (ii) the addition of gold nanoparticle gel and running buffer, and (iii) naked eye detection. Our platform is underpinned by selective thiolated aptamer-based recognition of 1,3-β-D glucan molecules-a hallmark of C. albicans cell walls. In the absence of C. albicans, wearable sample pads turn bright pink. In the presence of C. albicans, the wearable pads turn dark blue due to significant nanoparticle target-induced aggregation. We demonstrate naked-eye colorimetric detection of 4.4 × 106C. albicans cells per ml and nanoparticle stability over a pH range of 3.0-8.0. We believe that this proof-of-concept platform has the potential to have a significant impact on women's health globally.