Colorimetric Gas Sensing Washable Threads for Smart Textiles

The colorful world of sulfonephthaleins: Current applications in analytical chemistry for "old but gold" molecules

Sulfonephthaleins represent one of the most common and widely employed reactive dyes in analytical chemistry, thanks to their stability, low-cost, well-visible colors, reactivity and possibilities of chemical modification. Despite being first proposed in 1916, nowadays, these molecules play a fundamental role in biological and medical applications, environmental analyses, food quality monitoring and other fields, with a particular focus on low-cost and disposable devices or methods for practical applications. Since up to our knowledge, no reviews or book chapters focused explicitly on sulfonephthaleins have ever been published, in this review, we will briefly describe sulfonephthaleins history, their acid-base properties will be discussed, and the most recent applications in different fields will be presented, focusing on the last ten years literature (2014-2023). Finally, safety and environmental issues will be briefly discussed, despite being quite controversial.

Advances, challenges, and prospects for surgical suture materials

As one of the long-established and necessary medical devices, surgical sutures play an essentially important role in the closing and healing of damaged tissues and organs postoperatively. The recent advances in multiple disciplines, like materials science, engineering technology, and biomedicine, have facilitated the generation of various innovative surgical sutures with humanization and multi-functionalization. For instance, the application of numerous absorbable materials is assuredly a marvelous progression in terms of surgical sutures. Moreover, some fantastic results from recent laboratory research cannot be ignored either, ranging from the fiber generation to the suture structure, as well as the suture modification, functionalization, and even intellectualization. In this review, the suture materials, including natural or synthetic polymers, absorbable or non-absorbable polymers, and metal materials, were first introduced, and then their advantages and disadvantages were summarized. Then we introduced and discussed various fiber fabrication strategies for the production of surgical sutures. Noticeably, advanced nanofiber generation strategies were highlighted. This review further summarized a wide and diverse variety of suture structures and further discussed their different features. After that, we covered the advanced design and development of surgical sutures with multiple functionalizations, which mainly included surface coating technologies and direct drug-loading technologies. Meanwhile, the review highlighted some smart and intelligent sutures that can monitor the wound status in a real-time manner and provide on-demand therapies accordingly. Furthermore, some representative commercial sutures were also introduced and summarized. At the end of this review, we discussed the challenges and future prospects in the field of surgical sutures in depth. This review aims to provide a meaningful reference and guidance for the future design and fabrication of innovative surgical sutures. STATEMENT OF SIGNIFICANCE: This review article introduces the recent advances of surgical sutures, including material selection, fiber morphology, suture structure and construction, as well as suture modification, functionalization, and even intellectualization. Importantly, some innovative strategies for the construction of multifunctional sutures with predetermined biological properties are highlighted. Moreover, some important commercial suture products are systematically summarized and compared. This review also discusses the challenges and future prospects of advanced sutures in a deep manner. In all, this review is expected to arouse great interest from a broad group of readers in the fields of multifunctional biomaterials and regenerative medicine.

Phase-Dependent Dual Discrimination of MoSe2/MoO3 Composites Toward N,N-Dimethylformamide and Triethylamine at Room Temperature

Herein, we present, a chemiresistive-type gas sensor composed of two-dimensional 1T-2H phase MoSe2 and MoO3. Mixed phase MoSe2 and MoSe2/MoO3 composites were synthesized via a facile hydrothermal method. The structure analysis using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy revealed the formation of different phases of MoSe2 at different temperatures. With increase in synthesis temperature from 180 to 200 °C, the relative percentage of 1T and 2H-MoSe2 phases changed from 80 to 48%. On the other hand, at 220 °C, 2H-MoSe2 was obtained as a major component. The gas sensing properties of individual MoSe2 and composites were investigated at room temperature toward various analytes. The obtained results revealed that composites possess improved sensing features as compared with individual MoSe2 or MoO3. Data also revealed that the composite with dominating 1T-phase exhibits relatively higher response (10%, at 10 ppm) for dimethylformamide (DMF) compared to triethylamine (TEA) (3%, at 10 ppm). In contrast, the composite with larger 2H-phase exhibited affinity toward TEA and had a relative response of about 2%. Therefore, selectivity of a sensor device can be tuned by an appropriately designed MoSe2/MoO3 composite. These results signify the importance of MoO3-based composites with dual-phase MoSe2 for successfully discriminating between DMF and TEA at room-temperature.

A Review of Stimuli-Responsive Smart Materials for Wearable Technology in Healthcare: Retrospective, Perspective, and Prospective

In recent years thanks to the Internet of Things (IoT), the demand for the development of miniaturized and wearable sensors has skyrocketed. Among them, novel sensors for wearable medical devices are mostly needed. The aim of this review is to summarize the advancements in this field from current points of view, focusing on sensors embedded into textile fabrics. Indeed, they are portable, lightweight, and the best candidates for monitoring biometric parameters. The possibility of integrating chemical sensors into textiles has opened new markets in smart clothing. Many examples of these systems are represented by color-changing materials due to their capability of altering optical properties, including absorption, reflectance, and scattering, in response to different external stimuli (temperature, humidity, pH, or chemicals). With the goal of smart health monitoring, nanosized sol-gel precursors, bringing coupling agents into their chemical structure, were used to modify halochromic dyestuffs, both minimizing leaching from the treated surfaces and increasing photostability for the development of stimuli-responsive sensors. The literature about the sensing properties of functionalized halochromic azo dyestuffs applied to textile fabrics is reviewed to understand their potential for achieving remote monitoring of health parameters. Finally, challenges and future perspectives are discussed to envisage the developed strategies for the next generation of functionalized halochromic dyestuffs with biocompatible and real-time stimuli-responsive capabilities.

Diagnostic Approaches For COVID-19: Lessons Learned and the Path Forward

Coronavirus disease 2019 (COVID-19) is a transmitted respiratory disease caused by the infection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although humankind has experienced several outbreaks of infectious diseases, the COVID-19 pandemic has the highest rate of infection and has had high levels of social and economic repercussions. The current COVID-19 pandemic has highlighted the limitations of existing virological tests, which have failed to be adopted at a rate to properly slow the rapid spread of SARS-CoV-2. Pandemic preparedness has developed as a focus of many governments around the world in the event of a future outbreak. Despite the largely widespread availability of vaccines, the importance of testing has not diminished to monitor the evolution of the virus and the resulting stages of the pandemic. Therefore, developing diagnostic technology that serves as a line of defense has become imperative. In particular, that test should satisfy three criteria to be widely adopted: simplicity, economic feasibility, and accessibility. At the heart of it all, it must enable early diagnosis in the course of infection to reduce spread. However, diagnostic manufacturers need guidance on the optimal characteristics of a virological test to ensure pandemic preparedness and to aid in the effective treatment of viral infections. Nanomaterials are a decisive element in developing COVID-19 diagnostic kits as well as a key contributor to enhance the performance of existing tests. Our objective is to develop a profile of the criteria that should be available in a platform as the target product. In this work, virus detection tests were evaluated from the perspective of the COVID-19 pandemic, and then we generalized the requirements to develop a target product profile for a platform for virus detection.

Fast and noninvasive electronic nose for sniffing out COVID-19 based on exhaled breath-print recognition

The reverse transcription-quantitative polymerase chain reaction (RT-qPCR) approach has been widely used to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, instead of using it alone, clinicians often prefer to diagnose the coronavirus disease 2019 (COVID-19) by utilizing a combination of clinical signs and symptoms, laboratory test, imaging measurement (e.g., chest computed tomography scan), and multivariable clinical prediction models, including the electronic nose. Here, we report on the development and use of a low cost, noninvasive method to rapidly sniff out COVID-19 based on a portable electronic nose (GeNose C19) integrating an array of metal oxide semiconductor gas sensors, optimized feature extraction, and machine learning models. This approach was evaluated in profiling tests involving a total of 615 breath samples composed of 333 positive and 282 negative samples. The samples were obtained from 43 positive and 40 negative COVID-19 patients, respectively, and confirmed with RT-qPCR at two hospitals located in the Special Region of Yogyakarta, Indonesia. Four different machine learning algorithms (i.e., linear discriminant analysis, support vector machine, stacked multilayer perceptron, and deep neural network) were utilized to identify the top-performing pattern recognition methods and to obtain a high system detection accuracy (88–95%), sensitivity (86–94%), and specificity (88–95%) levels from the testing datasets. Our results suggest that GeNose C19 can be considered a highly potential breathalyzer for fast COVID-19 screening.

Unencapsulated and washable two-dimensional material electronic-textile for NO2 sensing in ambient air

Materials adopted in electronic gas sensors, such as chemiresistive-based NO₂ sensors, for integration in clothing fail to survive standard wash cycles due to the combined effect of aggressive chemicals in washing liquids and mechanical abrasion. Device failure can be mitigated by using encapsulation materials, which, however, reduces the sensor performance in terms of sensitivity, selectivity, and therefore utility. A highly sensitive NO₂ electronic textile (e-textile) sensor was fabricated on Nylon fabric, which is resistant to standard washing cycles, by coating Graphene Oxide (GO), and GO/Molybdenum disulfide (GO/MoS₂) and carrying out in situ reduction of the GO to Reduced Graphene Oxide (RGO). The GO/MoS₂ e-textile was selective to NO₂ and showed sensitivity to 20 ppb NO₂ in dry air (0.05%/ppb) and 100 ppb NO₂ in humid air (60% RH) with a limit of detection (LOD) of ~ 7.3 ppb. The selectivity and low LOD is achieved with the sensor operating at ambient temperatures (~ 20 °C). The sensor maintained its functionality after undergoing 100 cycles of standardised washing with no encapsulation. The relationship between temperature, humidity and sensor response was investigated. The e-textile sensor was embedded with a microcontroller system, enabling wireless transmission of the measurement data to a mobile phone. These results show the potential for integrating air quality sensors on washable clothing for high spatial resolution (< 25 cm²)—on-body personal exposure monitoring.

Flexible Sensory Systems: Structural Approaches

Biology is characterized by smooth, elastic, and nonplanar surfaces; as a consequence, soft electronics that enable interfacing with nonplanar surfaces allow applications that could not be achieved with the rigid and integrated circuits that exist today. Here, we review the latest examples of technologies and methods that can replace elasticity through a structural approach; these approaches can modify mechanical properties, thereby improving performance, while maintaining the existing material integrity. Furthermore, an overview of the recent progress in wave/wrinkle, stretchable interconnect, origami/kirigami, crack, nano/micro, and textile structures is provided. Finally, potential applications and expected developments in soft electronics are discussed.

QCM-Based HCl Gas Detection on Dimethylamine-Functionalized Crosslinked Copolymer Films

In this work, sensing behaviors and mechanisms of two crosslinked copolymers with dimethylamine and dimethylamide functional groups were compared and investigated for their ability to detect hydrogen chloride (HCl) gas. The crosslinked copolymer films were photopolymerized on quartz crystal electrodes using a micro-contact printing technique. The gas sensing behaviors were analyzed by measuring resonant frequency (Δf) of quartz crystal microbalance (QCM). The HCl binding capacity of photopolymerized films, with a mass between 4.6 and 5.9 μg, was optimized. Under optimized film mass conditions, the poly(2-dimethylaminoethyl methacrylate-co-ethylene glycol dimethacrylate) (DMAEMA-co-EGDMA), poly(DMAEMA-co-EGDMA), film, C2-DMA, showed a 13.9-fold higher binding capacity than the poly(N,N-dimethylacrylamide-co-ethylene glycol dimethacrylate, poly(DMAA-co-EGDMA), film, C0-DMA, during HCl gas adsorption. HCl gas was effectively adsorbed on the C2-DMA film because of the formation of tertiary amine salts through protonation and strong ionic bonding. Furthermore, the C2-DMA film exhibited excellent sensitivity, of 2.51 (ng/μg) (1/ppm), and selectivity coefficient (k* = 12.6 for formaldehyde and 13.5 for hydrogen fluoride) compared to the C0-DMA film. According to the experimental results, and due to its high functionality and stability, the C2-DMA film-coated QC electrode could be used as an HCl gas sensor, with low-cost and simple preparation, in future endeavors.

Washable and stretchable fiber with heat and ultraviolet color conversion

Wearable fabric-type color conversion sensors are very effective in quickly expressing danger or warnings to people. In particular, they can visually show information regarding the external environment, such as its temperature or ultraviolet (UV) intensity. However, a wearable sensor worn on the human body should maintain its sensing performance without deterioration even when exposed to various external stimuli, such as the repeated movements caused by human activity, sweat, and washing. In this study, thermochromic and UV photochromic fibers were fabricated to maintain stable color conversion functionality in response to temperature and UV irradiation even after continuous tensile-shrinkage, exposure to sweat and detergent solution. The thermochromic or UV photochromic materials were coated on the inside and outside of strands constituting a highly elastic spandex fiber. By adding polydimethylsiloxane to the color-changing material, the physical and chemical stability of the color-conversion thin film coated on the strand increased. The fabricated thermochromic fiber had a blue-green color and changed to white as the temperature increased, whereas the fabricated UV photochromic fiber was white and changed to purple as the UV intensity increased. In addition, the color conversion coating film was not lost even when exposed to repeated stretching and sweat/washing solutions, and a stable color-change reactivity was maintained. The thermochromic and UV photochromic fibers introduced in this study are expected to contribute to the commercialization of wearable colorimetric sensors by solving the problems regarding the physical stimulation and washing stability of existing coating-type color conversion fibers and textiles.

Thermochromic- and UV-photochromic-materials embedded stretchable fibers showed stable color conversion functionality in response to temperature and UV irradiation even after continuous tensile-shrinkage, exposure to sweat, and detergent exposure.

Quantitative volatile organic compound sensing with liquid crystal core fibers

Polymer fibers with liquid crystals (LCs) in the core have potential as autonomous sensors of airborne volatile organic compounds (VOCs), with a high surface-to-volume ratio enabling fast and sensitive response and an attractive non-woven textile form factor. We demonstrate their ability to continuously and quantitatively measure the concentration of toluene, cyclohexane, and isopropanol as representative VOCs, via the impact of each VOC on the LC birefringence. The response is fully reversible and repeatable over several cycles, the response time can be as low as seconds, and high sensitivity is achieved when the operating temperature is near the LC-isotropic transition temperature. We propose that a broad operating temperature range can be realized by combining fibers with different LC mixtures, yielding autonomous VOC sensors suitable for integration in apparel or in furniture that can compete with existing consumer-grade electronic VOC sensors in terms of sensitivity and response speed.

A Facile Design of Colourimetric Polyurethane Nanofibrous Sensor Containing Natural Indicator Dye for Detecting Ammonia Vapour

Chemicals and industrial gases endanger both human health and the environment. The inhalation of colourless ammonia gas (NH3) can cause organ damage or even death in humans. Colourimetric materials are becoming more popular in the search for smart textiles for both fashion and specific occupational applications. Colourimetric textile sensors based on indicator dyes could be very useful for detecting strong gaseous conditions and monitoring gas leaks. In this study, black carrot extract (BCE) as a natural indicator dye and polyurethane (PU) polymer were used to develop a colourimetric sensor by electrospinning. The properties of the BCE/PU nanofibrous mats were characterized by the Fourier transform infrared spectrum (FTIR) and a scanning electron microscope (SEM). The BCE caused a change in the morphology of the PU nanofibrous mat. To evaluate the colour shift due to NH3 vapour, the BCE/PU nanofibrous mats were photographed by a camera, and software was used to obtain the quantitative colour data (CIE L*a*b). The BCE/PU nanofibrous exhibited a remarkable colour change from pink-red to green-blue under NH3 vapour conditions with a fast response time (≤30 s). These findings showed that colourimetric nanofibrous textile sensors could be a promising in situ material in protective clothing that changes colour when exposed to harmful gases.

Microfluidic devices based on textile threads for analytical applications: state of the art and prospects

Microfluidic devices based on textile threads have interesting advantages when compared to systems made with traditional materials, such as polymers and inorganic substrates (especially silicon and glass). One of these significant advantages is the device fabrication process, made more cheap and simple, with little or no microfabrication apparatus. This review describes the fundamentals, applications, challenges, and prospects of microfluidic devices fabricated with textile threads. A wide range of applications is discussed, integrated with several analysis methods, such as electrochemical, colorimetric, electrophoretic, chromatographic, and fluorescence. Additionally, the integration of these devices with different substrates (e.g., 3D printed components or fabrics), other devices (e.g., smartphones), and microelectronics is described. These combinations have allowed the construction of fully portable devices and consequently the development of point-of-care and wearable analytical systems.

Non-invasive wearable chemical sensors in real-life applications

Over the past decade, non-invasive wearable chemical sensors have gained tremendous attention in the field of personal health monitoring and medical diagnosis. These sensors provide non-invasive, real-time, and continuous monitoring of targeted biomarkers with more simplicity than the conventional diagnostic approaches. This review primarily describes the substrate materials used for sensor fabrication, sample collection and handling, and analytical detection techniques that are utilized to detect biomarkers in different biofluids. Common substrates including paper, textile, and hydrogel for wearable sensor fabrication are discussed. Principles and applications of colorimetric and electrochemical detection in wearable chemical sensors are illustrated. Data transmission systems enabling wireless communication between the sensor and output devices are also discussed. Finally, examples of different designs of wearable chemical sensors including tattoos, garments, and accessories are shown. Successful development of non-invasive wearable chemical sensors will effectively help users to manage their personal health, predict the potential diseases, and eventually improve the overall quality of life.

A rapid and highly sensitive paper-based colorimetric device for the on-site screening of ammonia gas

A rapid and highly sensitive paper-based colorimetric device for the on-site detection of ammonia (NH₃) gas is presented in this study. The detection principle of this device is based upon a change of color from red to yellow on a paper that has been immobilized with a pH indicator, i.e., methyl orange (pK_a = 3.4), in the presence of NH₃ gas. The color signal of the device can be measured through the hue channel of an HSL system via the application of a smartphone. This device can detect the amount of NH₃ gas within 3 min. The linear relationship between the NH₃ gas concentration and the hue signal was found to be in the range from 6.0 to 54.0 ppbv with R² = 0.9971, and the limit of detection was found to be 2.0 ppbv. In addition, this device showed remarkably high selectivity to NH₃ gas amongst the other common volatile organic compounds and general gases that are present in environmental air without the assistance of any membrane material. Furthermore, we demonstrated the applicability of this device for the detection of total NH₃ gas at a chicken farm and in a laboratory, with relative standard deviations of 6.2% and 5.4%, respectively. The developed NH₃ gas device in the study is easy to operate and cost-effective, with the reduction of a large consumption of chemical reagents; also, its signals can be measured simply and then recorded through a smartphone. It is suitable for the application of routine on-site detection of NH₃ gas, especially concerning regions which have limited resources.

Head motion classification using thread-based sensor and machine learning algorithm

Human machine interfaces that can track head motion will result in advances in physical rehabilitation, improved augmented reality/virtual reality systems, and aid in the study of human behavior. This paper presents a head position monitoring and classification system using thin flexible strain sensing threads placed on the neck of an individual. A wireless circuit module consisting of impedance readout circuitry and a Bluetooth module records and transmits strain information to a computer. A data processing algorithm for motion recognition provides near real-time quantification of head position. Incoming data is filtered, normalized and divided into data segments. A set of features is extracted from each data segment and employed as input to nine classifiers including Support Vector Machine, Naive Bayes and KNN for position prediction. A testing accuracy of around 92% was achieved for a set of nine head orientations. Results indicate that this human machine interface platform is accurate, flexible, easy to use, and cost effective.

Coating of Conducting and Insulating Threads with Porous MOF Particles through Langmuir-Blodgett Technique

The Langmuir-Blodgett (LB) method is a well-known deposition technique for the fabrication of ordered monolayer and multilayer thin films of nanomaterials onto different substrates that plays a critical role in the development of functional devices for various applications. This paper describes detailed studies about the best coating configuration for nanoparticles of a porous metal-organic framework (MOF) onto both insulating or conductive threads and nylon fiber. We design and fabricate customized polymethylmethacrylate sheets (PMMA) holders to deposit MOF layers onto the threads or fiber using the LB technique. Two different orientations, namely, horizontal and vertical, are used to deposit MIL-96(Al) monolayer films onto five different types of threads and nylon fiber. These studies show that LB film formation strongly depends on deposition orientation and the type of threads or fiber. Among all the samples tested, cotton thread and nylon fiber with vertical deposition show more homogenous monolayer coverage. In the case of conductive threads, the MOF particles tend to aggregate between the conductive thread’s fibers instead of forming a continuous monolayer coating. Our results show a significant contribution in terms of MOF monolayer deposition onto single fiber and threads that will contribute to the fabrication of single fiber or thread-based devices in the future.

Disposable and Low-Cost Colorimetric Sensors for Environmental Analysis

Environmental contamination affects human health and reduces the quality of life. Therefore, the monitoring of water and air quality is important, ensuring that all areas are acquiescent with the current legislation. Colorimetric sensors deliver quick, naked-eye detection, low-cost, and adequate determination of environmental analytes. In particular, disposable sensors are cheap and easy-to-use devices for single-shot measurements. Due to increasing requests for in situ analysis or resource-limited zones, disposable sensors’ development has increased. This review provides a brief insight into low-cost and disposable colorimetric sensors currently used for environmental analysis. The advantages and disadvantages of different colorimetric devices for environmental analysis are discussed.

Colorimetric Textile Sensor for the Simultaneous Detection of NH3 and HCl Gases

For the immediate detection of strong gaseous alkalis and acids, colorimetric textile sensors based on halochromic dyes are highly valuable for monitoring gas leakages. To date, colorimetric textile sensors for dual-gas detection have usually been fabricated by electrospinning methods. Although nanofibrous sensors have excellent pH sensitivity, they are difficult to use commercially because of their low durability, low productivity, and high production costs. In this study, we introduce novel textile sensors with high pH sensitivity and durability via a facile and low-cost screen-printing method. To fabricate these textiles sensors, Dye 3 and RhYK dyes were both incorporated into a polyester fabric. The fabricated sensors exhibited high detection rates (<10 s) and distinctive color changes under alkaline or acidic conditions, even at low gas concentrations. Furthermore, the fabricated sensors showed an outstanding durability and reversibility after washing and drying and were confirmed to contain limited amounts of hazardous materials. Thus, our results show that the fabricated textile sensors could be used in safety apparel that changes its color in the presence of harmful gases.

Washable Colorimetric Nanofiber Nonwoven for Ammonia Gas Detection

The colorimetric sensor is a facile, cost-effective, and non-power-operated green energy material for gas detection. In this study, the colorimetric sensing property of a meta-aramid/dye 3 nanofiber sensor for ammonia (NH₃) gas detection was investigated. This colorimetric sensor was prepared using various dye 3 concentrations via electrospinning. Morphological, thermal, structural, and mechanical analyses of the sensor were carried out by field-emission scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and a universal testing machine, respectively. A homemade computer color matching machine connected with a gas flow device characterized the response of the meta-aramid/dye 3 nanofiber colorimetric sensor to various exposure levels of NH₃ gas. From the results, we confirmed that this colorimetric green energy sensor could detect ammonia gas in the concentration of 1-10 ppm with a sensing response time of 10 s at room temperature. After washing with laundry detergent for 30 min, the colorimetric sensors still exhibited sensing property and reversibility.

Highly Selective Metal-Organic Framework Textile Humidity Sensor

The increase in demand and popularity of smart textiles brings new and innovative ideas to develop a diverse range of textile-based devices for our daily life applications. Smart textile-based sensors (TEX sensors) become attractive due to the potential to replace current solid-state sensor devices with flexible and wearable devices. We have developed a smart textile sensor for humidity detection using a metal-organic framework (MOF) as an active thin-film layer. We show for the first time the use of the Langmuir-Blodgett (LB) technique for the deposition of a MIL-96(Al) MOF thin film directly onto the fabrics containing interdigitated textile electrodes for the fabrication of a highly selective humidity sensor. The humidity sensors were made from two different types of textiles, namely, linen and cotton, with the linen-based sensor giving the best response due to better coverage of MOF. The TEX sensor showed a reproducible response after multiple cycles of measurements. After 3 weeks of storage, the sensor showed a moderate decrease in response. Moreover, TEX sensors showed a high level of selectivity for the detection of water vapors in the presence of several volatile organic compounds (VOCs). Interestingly, the selectivity is superior to some of the previously reported MOF-coated solid-state interdigitated electrode devices and textile sensors. The method herein described is generic and can be extended to other textiles and coating materials for the detection of toxic gases and vapors.

S. G, Peralam Yegneswaran P, Prabhu V, Verma U, Mani NK. Thread integrated smart-phone imaging facilitates early turning point colorimetric assay for microbes

A proof-of-concept unifying thread devices and smart-phone imaging for low-cost microbial detection based on simple colour change.

Highly Flexible Transistor Threads for All-Thread Based Integrated Circuits and Multiplexed Diagnostics

Physically intimate, real-time monitoring of human biomarkers is becoming increasingly important to modern medicine and patient wellness. Such monitoring is possible due to advances in soft and flexible materials, devices and bioelectronics systems. Compared to other flexible platforms, multifilament textile fibers or threads offer superior flexibility, material diversity, and simple ambient processing to realize a wide range of flexible devices such as sensors, electronics, and microfluidics. In this paper, we realize unique flexible transistors on threads and interconnect them to realize logic gates and small-scale integrated circuits. Compared to prior textile-based transistors, the proposed thread-based transistors (TBTs) are realized with a readily shaped, colloidally dispersed gel consisting of silica nanoparticles and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI) ionic liquid for all-around electrolyte gating of a carbon nanotube (CNT) semiconducting network assembled on the thread. We interconnect TBTs with thread-based electrochemical sensors (TBEs) to realize an all-thread based multiplexed diagnostic device. All-thread based platforms are thin, highly flexible and conformal, allowing them to be worn directly on the skin without any polymeric substrate, or sutured transdermally using a needle.