Electronic Textiles & Skin Patches: Hardware & Software

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Smart watches, rings, or accessories utilize optical sensors and accelerometers combined with powerful machine learning create exciting algorithms allowing parameters such as steps, calories, heart rate and its derivatives, blood oxygen, and sleep pattern to be predicted. The Quantified Self industry blossoms and wearable gadgets are now everywhere. We believe that wearable technology is still in its infancy and there are great potentials for the technology to disrupt existing clinical practices and aspire to diagnose or predict the onset of diseases that were once believed to be unpredictable. This presentation discusses pathways and activities needed to build wearable products beyond their current consumer-grade paving the way for wearable as a medical-grade device. Two specific examples will also be presented. The first example relates to how we use our wearables to discover a unique novel parameter that correlates to acute stress and how it is being utilized to improve the service of mental health counselling. The second example focuses on characterizing and correcting skin tone biased, an inherent problem associated with optical sensor, in pulse oximetry which has recently been reported for its racial and ethnic discrepancy.

Wearables and sensors are playing an increasingly important role in elderly care. Against the background of sociodemographic change and the lack of personnel, elderly care must be made more effective and efficient. IoT approaches can provide significant support in this regard. This presentation deals with the technology readiness level of existing solutions and outlines different use cases from the field.

As a concrete example, we will also present the digital care assistant we have developed using wearable sensors and low-cost printed electronics that can be integrated into any diaper, providing smart incontinence management, bed sore prevention, fall detection and resident localisation. We will discuss the impact this has had on residents wellbeing and carehome activities, and the challenges and lessons encountered on the way.

Wearables and sensors are playing an increasingly important role in elderly care. Against the background of sociodemographic change and the lack of personnel, elderly care must be made more effective and efficient. IoT approaches can provide significant support in this regard. This presentation deals with the technology readiness level of existing solutions and outlines different use cases from the field.

As a concrete example, we will also present the digital care assistant we have developed using wearable sensors and low-cost printed electronics that can be integrated into any diaper, providing smart incontinence management, bed sore prevention, fall detection and resident localisation. We will discuss the impact this has had on residents wellbeing and carehome activities, and the challenges and lessons encountered on the way.

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We are developing an innovative body-worn ultrasound device in a patch-based form-factor. Our device will allow for a revolution in patient monitoring, by allowing images of critical organ function to be collected, continuously and non-invasively by a body-worn device. Our first application will be targeted for the cardiac space, but our technology allows to address many other medical applications. In this talk we will highlight the technology and innovation behind our ultrasound patch

Wearable devices offer unique opportunities to acquire biosignals and provide short-latency biofeedback. This opportunity generated an ever-increasing interest in the last decade with numerous developments and wearable device market launches. Despite the great interest, the spread of wearable devices is still limited to a few categories like smartwatches and sports trackers, with limited products exploiting the enormous potential applications arising from brain (EEG), heart (ECG), muscles (EMG), and eyes (EOG) biosignals. Employing bio-potential signals in wearable devices would allow the user to get real-time health feedback or more seamless interaction with machines (i.e. brain-computer interface - BCI). However, the reliable acquisition of bio-potentials in wearable devices is very challenging as it requires high-quality sensing interfaces with the user's skin, coupled with miniaturized and high-performance hardware and software to meet key requirements for wearables, such as ease of use, unobtrusiveness, and high return of engagement, to mention a few. Only recently, only a few wearable devices were able to successfully satisfy these combined requirements, and the few available products mainly target BCI development or the meditation market. In this contribution, we report the development of a fully integrated in-ear sensor for brain signal detection meeting real needs of ease of use, non-stigmatizing form factor and high performance for long-term and multiple uses.
Two main features made possible the development of this fully integrated sensor for long-term use, namely the dry sensors and the newly developed acquisition system. The dry sensors used in this contribution are made of electrically conductive rubber material with silver/silver chloride coating on the areas in contact with the skin. These electrodes combine improved wear comfort (with respect to rigid metal or plastic dry electrodes) with low skin impedance and short equilibration time in bio-potential acquisition. Additionally, they can be used hundreds of times without a decrease in performance. The used production technology allows easy customization and it can be adapted to low as well as to serial volumes. In this contribution, we chose a custom brush-like design allowing easy ear canal penetration and comfort of use.

The acquisition system was designed to optimize the device’s size, energy consumption, and provide significant in-situ signal processing capabilities while allowing energy-efficient biosignal acquisition. At its core, it integrates an Ultra-Low-Power medical-grade 24-bit Analog-Front-End (AFE) engineered for biopotential acquisition. The AFE is coupled with a BLE-capable ARM Cortex-M4 microcontroller, enabling the whole platform to perform onboard processing of acquired data or wirelessly transmit the raw biosignal. The device also includes a Low-Power MEMS microphone and an inertial measurement unit. All components fit into a small (15x16mm) printed circuit board that can easily be placed on top of the ear, as a regular earbud would. When doing online processing, the device only employs 1.3 mW (including the energy required to transmit processing results), allowing more than a month of operation.

The strong synergy between the innovative electrodes and the novel acquisition device was demonstrated for a challenging auditory response (AR) use case. During tests, the device detected auditory stimuli from the EEG signals with a sensitivity and specificity >80%, only with a few training epochs. These results confirm the potential of the wearable system for complex diagnostic tasks, such as objective hearing threshold estimation, even in out-of-the-lab conditions.

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I will discuss how remote monitoring have the potential to transform the way we monitor and manage our health. Remote monitoring devices have already proven to be effective in providing continuous monitoring of vital signs such as heart rate, respiratory rate among others.

Pain is a significant global problem. For decades healthcare professionals have tried to find a way to measure pain. Now with the new wearable technology it is finally possible. To treat the pain, we need to be able to measure the pain, to continuously monitor a patient's pain levels and respond promptly with appropriate interventions. Intelligent wearable technology have the potential to revolutionize the pain management field by providing accurate and objective pain assessment data. This can help clinicians make more informed decisions on pain treatment, reducing the risk of overmedication and improving patient outcomes. Additionally, continuous monitoring of pain can provide valuable insights into the effectiveness of pain management strategies and help identify patients who may be at risk of developing chronic pain. I believe that the integration of intelligent wearable technology with skin patches into pain management protocols can significantly improve patient care and outcomes.
The key advantage of intelligent remote monitoring device is that they can be worn continuously without causing any discomfort to the user. This makes them ideal for patients who require long-term monitoring or those who need to be monitored remotely.

In my talk, I will also focus on the importance of signal processing and AI in ensuring that the captured data from the remote monitoring devices is reliable. Signal processing algorithms can help filter out noise and other unwanted signals, while AI can analyze the data to detect patterns and anomalies. This can help clinicians make more informed decisions and provide better care to their patients.

Finally, I will discuss the challenges that still need to be addressed in the development and implementation of intelligent remote monitoring devices. These include issues related to data privacy and security, regulatory approval, and cost-effectiveness. However, I am optimistic that these challenges can be overcome with continued innovation and collaboration between researchers, clinicians, and industry stakeholders.

In conclusion, remote monitoring have the potential to revolutionize the way we monitor and manage our health. They offer a non-invasive, comfortable, and continuous monitoring solution that can improve patient outcomes and reduce healthcare costs. I look forward to sharing my insights on this topic at your upcoming event.

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In this presentation, we will discuss the use of printed electronics in the development of customised electrode patches and smart textiles. Quad Industries has leveraged this technology to create innovative wearable healthcare products that offer several advantages over traditional approaches. Through the use of practical use cases, we will showcase the benefits of printed electronics, including enhanced comfort, flexibility, and functionality. Our presentation will demonstrate how this technology is revolutionizing the field of wearable healthcare, and we will provide insights into the potential for further innovation in this exciting area.

Discussing how healthcare-at-home remote diagnostics and clinical decision support utilizing A.I. / M.L.from wearables and e-textiles is now a prominent focus for all stakeholders in healthcare.
Shedding light on how textile-digital solutions are limited in the clinical and diagnostic services for dynamic data, particularly those utilizing A.I. / M.L.
Rethinking how textile + plus digital

Technical embroidery systems, due to their high precision, are applicable for the integration of functionality into textiles through textile sensors, actuators, electrodes and functional LED or RFID sequins. Even entire circuit boards (PCBs) can be automatically and reliably fixed and connected with conductive threads. Technical Embroidery systems provide solutions to two of the greatest challenges of the e-textiles industry by creating a reliable interface between the electronic components and the textile and enabling the automated mass production of smart and e-textiles.

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Neurotechnology research is making real the possibility of human brain and nervous system activity being measured and altered. Neurosensing can lead to better interfaces with technology, an increased understanding of the effectiveness of medication, and new insights into how the nervous system helps regulate physiology and biochemistry. Neuromodulation is enabling new approaches to therapies for rheumatoid arthritis, tinnitus, stroke, and Parkinson’s disease using wearable devices.

An overview of the variety of research at Stanford U. related to wearable eurotechnology will be presented, such as the following examples. Haptic wristbands stimulate nerves to create the perception of grasping an object in VR while leaving hands free. A functional Near-Infrared Spectroscopy (fNIRS) headband is in development for measuring blood flow changes in the brain that correspond to different mental states and may be used for biofeedback to reduce stress. Whereas electrocardiography (ECG) patches on the chest sense signals from the heart and detect arrhythmia, wearable sensors on the abdomen measure contractions of the stomach and gut to model the function of organs and help
clinicians diagnose digestive issues.

Electromyography (EMG) can be used with biofeedback to help individuals modify their walking gait to reduce long-term knee injury or improve athletic performance. EMG signals for muscles occur before the motion, which may lead to prediction of movement and increased responsiveness for exoskeletons.

Arrays of stretchable electrodes on the surface of the skin enable greater EMG precision than discrete electrodes when reading electrical signals. These e-skin arrays potentially lead to smoother control of robotics, feedback when training for delicate tasks, and more realistic interactions in VR.

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Our research has resulted in the development of an innovative intelligent clothing technology that utilizes flexible textile-integrated metamaterials to create secure, seamless, and versatile communication links for multi-node wireless networks. By driving long-distance near-field communication (NFC)-based magneto-inductive waves along and between multiple objects, we have overcome the typical limitations of body area networks, such as short ranges, low power, and the need for direct connection terminals. Our approach enables battery-free communication among NFC-enabled devices that are placed anywhere close to the network, providing a secure and on-demand body area network that exhibits complex architectures and straightforward expansion.

One of the key advantages of our technology is that it utilizes NFC, the only wireless technology that allows power transmission, providing a significant advantage over Bluetooth or Wi-Fi. We have designed lightweight, battery-free sensors with small form factors that are integrated into human clothing, resulting in the first intelligent clothes that can monitor a wide range of human activities. Unlike computer vision-based technologies, our solution does respect users' privacy, making it an ideal solution for advanced healthcare monitoring technologies. Overall, our intelligent clothing technology represents a significant step forward in the development of wearable and implantable sensors for healthcare monitoring, offering a secure and versatile communication platform that can be easily integrated into everyday clothing.

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The ability to weave sensors and actuators into conventional clothing generates enormous potential. Our team has successfully produced microfiber sensors that are thin, weavable, and washable, yet remarkably sensitive in their ability to detect minute movements, muscle contractions, and even vital signs. Additionally, their one-dimensional form factor permits seamless integration with complex three-dimensional architectures.
In this presentation, I will highlight the use of our sensors in the sports domain, demonstrating exceptional accuracy in measuring muscle expansion and contraction. The implications for strength training are particularly noteworthy. Equipped with AI-powered recommendations, users can make informed decisions based on data that can be accessed anywhere, anytime.
Moreover, our microfiber technology also has the capacity to serve as a soft actuator, enabling the development of wearable haptic technology. I will be presenting our research on the potential application of this technology in the healthcare metaverse.

The convergence of lab-based discoveries and industry-need created reimagined products based on stretchable and/or flexible substrates.
Soft electronics made of silicone were translated into a printed technology to create smart bedding products to monitor aged-care residents and improve quality of care. Working closely with manufacturers, the evolution of the technology from stretchable electrodes to a sensor array across a mattress, will be covered. This approach represented a new take on production of electronic textiles.
Combining flexible substrates with surface mount components, composite structures have created a category of modular sensing skin patches. Based on clinical need, different sensor combinations have been utilised for aged-care health monitoring, with potential use cases targeted to dementia care and post-operative management.

Continuous physiological monitoring for sleep apnea detection, is usually achievable by body-attached mechanical sensors, body-attached electrodes, or remote ultrasound sensors. With current systems the user has 15 wires and tubes connected to his body. The main pain-point sensor is the oronasal one that measure the air flow, hence the respiration. A sleep apnea event is when respiration is reduced during sleep.
When used at home, such bulky systems don’t allow natural sleep and generate false positives and negatives. All serious medical devices respect the American Academy of Sleep Medicine (AASM) who is followed by the sleep specialists and health insurances. The AASM issued its rules where sleep apnea detection devices can be simplified, cheaper and easier to access to.

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The first ideas and patents of textile electromyography (muscle activity measurement, shirt - EMG for short) are already more than 120 years old. Nevertheless, no functioning textile and mobile EMG system exists as of 2023. This presentation describes challenges, current developments, trends and possibilities to make a system feasible by the 125th anniversary.
Historically, the signal-to-noise ratio was a major hurdle, but today a wide range of materials is available for measurement. This raises the issues of mobility, biocompatibility, contact to the skin and stretchability.
Even than measuring EMG signals is relatively easy, but there are great difficulties with the correct interpretation of the signals to reveal the whole potential of knowing one’s muscles.
This lecture specialises explicitly in the field of printed electromyography.

Correct breathing is an important aspect of any exercise, as it impacts the efficiency of exercise and the ability of the practitioner to reach their goals. Proper breathing is especially critical in fitness and recovery exercises, where breathing rate and depth should be optimized towards a specific fitness or recovery goal. However, there is no widely available technology to track breathing in real time as it occurs, and none that is tailored for the fitness and recovery markets. In this presentation, we will review the state of the art in real-time breathing monitoring, contrasting that to our own wearable patch that is designed to be lightweight, user-friendly and comfortable. The patch is paired with an app that is tailored for use in fitness optimization. We will outline the potential of this solution on the fitness and recovery markets."

Chronic low back pain is one of today’s major global health problems, and current standard of care may often provide only limited relief. Auricular vagus nerve stimulation can be a promising adjunct treatment. With a wearable electrical neuromodulation device, the vagus nerve can be stimulated in a minimally-invasive way in the auricle. The method was tested to be effective and safe. By personalization of stimulation the therapeutic effect can be improved. Integrated biosensors can be used to measure physiological data and the stimulation can be adjusted accordingly.

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In the development of e-textiles, 2 very different worlds meet.
It is therefore particularly important to set the right course right from the start in order to be successful, both economically and in terms of achieving the goals that have been set.

Gallium-based liquid metals have remarkable properties: melting points below room temperature, water-like viscosity, low-toxicity (unlike Hg), and effectively zero vapor pressure (they don’t evaporate). They also have, by far, the largest interfacial tension of any liquid at room temperature. Yet, these liquid metals can be patterned into non-spherical shapes (cones, wires, etc) due to a thin, oxide skin that forms rapidly on its surface. We have harnessed this oxide to pattern and manipulate metal into shapes—such as wires and particles—that are useful for applications that call for soft and deformable metallic features, such as wearables. It is possible to pattern the metal in a number of ways, including injection into microchannels or by direct-write 3D printing at room temperature, to form ultra-stretchable wires, deformable antennas, and microelectrodes. In addition, recently we have shown that liquid metals can be used in textiles that are highly conductive, breathable, and most interestingly, can “self-heal” autonomously when cut.
Furthermore, we have recently demonstrated for the first time the creation of stretchable gas barrier materials. Normally, stretchable materials are inherently permeable, which means it is not possible to encapsulate air sensitive electronic devices. We have used liquid metal, combined with elastomer, to create nearly perfect hermetic seals that can block water or oxygen from entering or leaving devices. Such materials can be used to encase stretchable batteries to prevent leakage of electrolyte (and thus, battery degradation) with respect to time. The talk will discuss the implications of these materials for soft and stretchable electronics; that is, devices with desirable mechanical properties for human-machine interfacing, soft robotics, and wearable electronics.

In the proposed technology, we are developing a Nano-Hybrid platform smart fiber yarn for multifunctional application. The fiber is functionalized with a specific nanoparticle, and the fiber yarn is coated with specific dye molecules. Through the coverup process, we create a composite yarn by further combining it with an LED embedded Fiber. We are establishing a mechanism called Photodynamic Therapy (PDT) which is a long-established approach to generate reactive oxygen species (ROS) using photosensitizers (PS) and visible light. PDT is a local and selective treatment that has existed for many years to cure premalignant diseases, antimicrobial or cancers. This treatment requires the presence of three elements within the target area, a photosensitizer (PS), which is a photoactivable molecule that can react with oxygen when excited by photons and produces toxic species that will destroy the cancerous cells, pathogens; a light of a specific wavelength and intensity that activates the PS; and oxygen molecules, naturally present in the biological medium. This therapy finds many applications in diverse medical fields.
However, dermatology is one of the disciplines where PDT is the more used as first-line treatment since the targeted sites (skin) are easily reachable by light. Moreover, it has proven its efficacy in several main dermatological indications: like actinic keratoses, Basal cell carcinoma (BCC). These applications of PDT on skin gave us an insight to create a PDT based Nano-Hybrid textile yarn.
Here, by using a tiny LED extruded into a monofilament yarn, we are creating a synergy between the LED light and the nano hybrid system. We are shining light with the LED embedded fiber yarn that aligns closely to the nanoparticle functionalized dye coated yarn to stimulate thermoregulating and therapeutic functionalities. We can tune the emission and excitation of the additives we add during the process by controlling several aspects of the nanoparticles/additives – the size, shape, and phase. This multifunctional composite yarn has potential use for antimicrobial, wound healing and thermoregulating textile applications.

The integration of microelectronics in textiles has been a growing trend, especially in injury prevention, elite sports, space exploration and film animation. This trend poses new challenges to both the electronics and clothing industry in terms of product design, material selection, washability and sustainable recycling/disposal. Danish Technological Institute (DTI) is in forefront of this development. In the talk, we will highlight how printed electronics can support the development of the next generation of smart wearables. We will also give a live tour in our lab to present some of the advanced equipment that is available for companies in this space.

The integration of microelectronics in textiles has been a growing trend, especially in injury prevention, elite sports, space exploration and film animation. This trend poses new challenges to both the electronics and clothing industry in terms of product design, material selection, washability and sustainable recycling/disposal. Danish Technological Institute (DTI) is in forefront of this development. In the talk, we will highlight how printed electronics can support the development of the next generation of smart wearables. We will also give a live tour in our lab to present some of the advanced equipment that is available for companies in this space.

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One of the most prevalent challenges in measuring bio signals chronically with high sampling rates chronically are stable skin interfaces and advanced power requirements. We provide solutions that enable months long operation without subject interaction and high sampling rates through wireless power transfer and personalized wearable platforms.

There is nothing more personal than healthcare. Health care should move from its current reactive and disease-centric system to a personalized, predictive, preventative, and participatory model with a focus on disease prevention and health promotion. As the world marches into the era of the Internet of Things (IoT) and 5G wireless, technology renovation enables the industry to offer a more individually tailored approach to healthcare with better health outcomes, higher quality, and lower cost. However, empowering the utility of IoT-enabled technologies for personalized health care is still significantly challenged by the shortage of cost-effective on-body biomedical devices to continuously provide real-time, patient-generated health data. Textiles have been concomitant and played a vital role in the long history of human civilization. Incorporating sensing and therapeutic capabilities into everyday textiles could be a powerful approach to the development of personalized healthcare. Merging biomedical devices and textiles becomes increasingly important owing to the growing trend of IoT since it could serve as on-body healthcare platforms with incomparable wearing comfort. In this talk, I will introduce our current research on smart textiles for biomonitoring, therapeutics, power supply, and textiles body area network for personalized health care.

Recording, modelling and understanding tactile interactions is important in the study of human behaviour and in the development of applications in healthcare and robotics. However, such studies remain challenging because existing wearable sensory interfaces are limited in terms of performance, flexibility, scalability and cost. In this talk, I will talk about a textile-based tactile learning platform that can be used to record, monitor and learn human–environment interactions. The tactile textiles are created via digital machine knitting of inexpensive piezoresistive fibres, and can conform to arbitrary three-dimensional geometries. To ensure that our system is robust against variations in individual sensors, we use machine learning techniques for sensing correction and calibration. Using the platform, we capture diverse human–environment interactions (more than a million tactile frames) and show that the artificial-intelligence-powered sensing textiles can classify humans’ sitting poses, motions and other interactions with the environment. We show that the platform can recover dynamic whole-body poses, reveal environmental spatial information and discover biomechanical signatures.

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Here, we demonstrate electronic textile systems with functionalities in near-field powering and communication created by the digital embroidery of liquid metal fibers. Owing to the unique electrical and mechanical properties of the liquid metal fibers, these electronic textiles can conform to body surfaces and establish robust wireless connectivity with nearby wearable or implantable devices, even during strenuous exercise. By transferring optimized electromagnetic patterns onto clothing in this way, we demonstrate a washable electronic shirt that can endure repeated mechanical, thermal & chemical stresses; and can be wirelessly powered by a smartphone to continuously monitor the axillary temperature without interfering with daily activities.

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Fiber electronics are of considerable interest for wearable applications and smart textiles, and they can facilitate communication and the interaction between humans and surroundings. As a basic element of functional textiles, the one-dimensional (1D) form of thread-like fibers offers high flexibility,isotropic deformations, breathability, and light weight in fabric structures. The 1D functional fibers can be further processed into two-dimensional (2D) textile and three-dimensional (3D) yarn configurations through traditional textile engineering techniques, such as twisting, weaving, sewing, knitting, knotting, and interlacing. Owing to such intrinsic merits, in recent years, fiber-based device components that perform optoelectronic functions, such as health/environmental monitoring, displays, sensing, energy harvesting, energy storage, electromagnetic shielding, and information processing, have been integrated directly into fabrics to demonstrate futuristic clothes. The existing electronic fiber platforms are generally composed of only one type of electronic component with a single function on a fiber substrate that is attributed to all around wrapping of an active layer on the entire fiber without patterning at the desired area on the surface of the fiber during the manufacturing process. Moreover, a precise connecting process between each electronic fiber is essential to configure the desired electronic circuits or systems into the 2D textile while minimizing the degradation of the device performance. Although assembly of those functional fibers can be used for recording, detecting, and readout data sequentially, similar to conventional integrated circuits and multifunctional devices on 2D wafers, both limitations on scaling down and difficulty in the configuration of the electronic circuit remain major obstacles for the implementation of practical electronic fiber systems. To impart multiple functions to the textile, the methods of inserting small electronic components into a fiber strand or yarn have been considered emerging candidates, enabling the implementation of a thermally drawn digital fiber and e-yarn. However, a limitation to the thermal drawing approach and the mounting of small components on the top surface of a filament is the low device density. A new strategy to fabricate a high-density electronic microfiber possessing multiple electronic components and circuits as well as maintaining excellent electrical performance has not yet been reported. In this work, we present a new electronic fiber platform that enables LSI of electronic device components on the surface of a 1D fiber, defined as a monofilament with a diameter of 150 μm. By using high-resolution maskless photolithography with a capillary tube-assisted coating method, multiple miniaturized device units are integrated onto a very narrow and thin fiber surface.

As a proof-of-concept demonstration, basic electronic devices (field-effect transistors, inverters, and ring oscillators) and sensors (photodetectors, signal transducer, and distributed temperature sensors consisting of thermocouples) are fabricated onto the two different sides of the rectangular fiber. The chip on a fiber exhibits various electronic functions (UV detection and switching electrical signals in a single transistor, symmetric input/output behaviour in the n-type inverter, oscillation characteristics of 5-stage ring oscillator) and thermal sensing performance. We believe that our approach is one of the big steps to implement a high-density electronic fiber platform for integrated electronic textiles.

Fibre electronics are of considerable interest for wearable applications and smart textiles, and they can facilitate communication and the interaction between humans and surroundings. As a basic element of functional textiles, the one-dimensional (1D) form of thread-like fibres offers high flexibility, isotropic deformations, breathability, and light weight in fabric structures. The 1D functional fibres can be further processed into two-dimensional (2D) textile and three-dimensional (3D) yarn configurations through traditional textile engineering techniques, such as twisting, weaving, sewing, knitting, knotting, and interlacing. Owing to such intrinsic merits, in recent years, fibre-based device components that perform optoelectronic functions, such as health/environmental monitoring, displays,sensing, energy harvesting, energy storage, electromagnetic shielding, and information processing, have been integrated directly into fabrics to demonstrate futuristic clothes. The existing electronic fibre platforms are generally composed of only one type of electronic component with a single function on a fibre substrate that is attributed to all around wrapping of an active layer on the entire fibre without patterning at the desired area on the surface of the fibre during the manufacturing process. Moreover, a precise connecting process between each electronic fibre is essential to configure the desired electronic circuits or systems into the 2D textile while minimizing the degradation of the device performance. Although assembly of those functional fibres can be used for recording, detecting, and readout data sequentially, similar to conventional integrated circuits and multifunctional devices on 2D wafers, both limitations on scaling down and difficulty in the configuration of the electronic circuit remain major obstacles for the implementation of practical electronic fibre systems. To impart multiple functions to the textile, the methods of inserting small electronic components into a fibre strand or yarn have been considered emerging candidates, enabling the implementation of a thermally drawn digital fibre and e-yarn. However, a limitation to the thermal drawing approach and the mounting of small components on the top surface of a filament is the low device density. A new strategy to fabricate a high-density electronic microfibre possessing multiple electronic components and circuits as well as maintaining excellent electrical performance has not yet been reported.

In this work, we present a new electronic fibre platform that enables LSI of electronic device components on the surface of a 1D fibre, defined as a monofilament with a diameter of 150 μm. By using high-resolution maskless photolithography with a capillary tube-assisted coating method, multiple miniaturized device units are integrated onto a very narrow and thin fibre surface. As a proof-of-concept demonstration, basic electronic devices (field-effect transistors, inverters, and ring oscillators) and sensors (photodetectors, signal transducer, and distributed temperature sensors consisting of thermocouples) are fabricated onto the two different sides of the rectangular fibre. The chip on a fibre exhibits various electronic functions (UV detection and switching electrical signals in a single transistor, symmetric input/output behaviour in the n-type inverter, oscillation characteristics of 5-stage ring oscillator) and thermal sensing performance. We believe that our approach is one of the big steps to implement a high-density electronic fibre platform for integrated electronic textiles.