Fabric-based Device Research Articles

MediKnit: Soft Medical Making for Personalized and Clinician-Designed Wearable Devices for Hand Edema

Current rapid prototyping in medical domains relies on rigid 3D-printed materials, lacking flexibility, customization, and clinician-led input. This paper introduces MediKnit, a novel approach for the fabrication of soft medical devices, addressing critical limitations in existing design processes for medical devices. MediKnit provides a design tool empowering clinicians to personalize fabric-based devices for hand edema. This tool allows clinicians to adapt the design to individual patients' demands, thereby enhancing the overall effectiveness of therapy. The MediKnit device created by this tool consists of a machine-knit glove with active compression, which is programmable through a custom PCB. This device facilitates the mobilization of edema. To illustrate the practical implementation of our approach, this paper presents case studies involving six patients experiencing hand edema. The results demonstrate the adaptability and feasibility of our process for developing soft medical devices, highlighting its potential to broaden accessibility, facilitate personalized solutions, and empower clinicians as active medical makers.

Large-Area Fabrication of Porous Graphene Networks on Carbon Fabric via Millisecond Photothermal Processing of Polyaniline for Supercapacitors.

Supercapacitors demonstrate promising potential for flexible, multi-functional energy storage devices; however, their widespread adoption is confronted by fabrication challenges. To access a combination of desirable device qualities such as flexibility, lightweight, structural stability, and enhanced electrochemical performance, carbon fiber (CF) can be utilized as a current collector, alongside graphene as an electrochemically active material. Yet achieving a cost-effective, large-scale graphene production, particularly on CF, remains challenging. Here, a rapid (<1min) photothermal approach is developed for the large-scale production of graphene directly onto CF, utilizing polyaniline (PANI) as a polymer precursor. The in situ electropolymerization of PANI on CF facilitates its rapid synthesis on large areas, followed by conversion into graphene networks, enabling the binder-free fabrication of supercapacitor devices. These devices exhibit an areal capacitance of 180mFcm-2 (at 2mAcm-2 in 1mH2SO4), an order of magnitude higher than other fabric-based devices. Moreover, the devised photothermal strategy allows for one-step preparation of supercapacitor devices on areas exceeding 100cm-2, yielding an absolute areal capacitance of 4.5F. The proportional increase in capacitance with device area facilitates scaling and indicates the commercial viability of this approach for low-cost, energy-efficient, and high-throughput production of lightweight, high-performance graphene-based multi-functional supercapacitor devices.

Ni-P Electroless Plating of Polyethylene Terephthalate Fibers with Various Twist Number Utilizing Supercritical CO2-Assisted Catalyzation

Weavable devices are multifunctional fabric-based devices prepared by weaving various functional fibers into a single piece of fabric. Metalized polymer fibers are promising electrical conductors for such weavable devices because of the decnet electrical conductivity derived from the metal coating and flexibility arising from the polymer fiber. However, ensuring both sufficient electrical conductivity and stability in these metalized polymer fibers for practical device application remains challenging because of the insufficent adhesion between the metal coating and polymer fiber. An electroless plating with the catalyzation step performed in supercritical carbon dioxide (sc-CO2)1 is developed to produce metallized polymers possessing high electrical conductivity and good adhesive properties between the metal coating and polymer fiber. In application, fibers are often twisted to enhance a specific property, such as the mechanical property, and the twist number (twist per meter, T/m) is expected to affect the electroless plating performance.In this presentation, Ni-P electroless plating of polyethylene terephthalate (PET) fibers with a different twist number (twist per meter, T/m) is reported. The sc-CO2-assisted catalyzation was utilized to achieve electroless plating of Ni-P coatings on the PET fibers. The electrical resistance of the Ni-P/PET fibers was decreased following an increase in the twist number as listed in Table 1. Elemental analyses revealed that the Ni content in the Ni-P coating was higher for the PET fibers with a larger twist number. This tendency corresponded well the the electrical resistance results since Ni-P with a higher Ni content is expected to have a lower electrical resistance. Results obtained in this study indicate that PET fibers with a larger twist number is beneficial for the electroless Ni-P plating by decreasing of the electrical resistance in the fabricated Ni-P/PET fibers. Reference T.-F.M. Chang et al., Microelectron. Eng. 2020, 223, 111233. Figure 1

Efficient Flexible Fabric-Based Top-Emitting Polymer Light-Emitting Devices for Wearable Electronics.

Low-cost fabric-based top-emitting polymer light-emitting devices (Fa-TPLEDs) have aroused increasing attention due to their remarkable potential applications in wearable displays. However, it is still challenging to realize efficient all-solution-processed devices from bottom electrodes to top electrodes with large-scale fabrication. Here, a smooth reflective Ag cathode integrated on fabric by one-step silver mirror reaction and a composite transparent anode of polydimethylsiloxane/silver nanowires/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) via a water-assisted peeling method are presented, both of which possess excellent optoelectrical properties and robust mechanical flexibility. The Fa-TPLEDs are constructed by spin-coating functional layers on the bottom reflective cathodes and laminating the top transparent anodes. The Fa-TPLEDs show a current efficiency of 16.3cdA-1 , an external quantum efficiency of 4.9% and angle-independent electroluminescence spectra. In addition, the Fa-TPLEDs possess excellent mechanical stability, maintaining a current efficiency of 14.3cdA-1 after 200 bending cycles at a radius of 4mm. The results demonstrate that the integration of solution-processed reflective cathodes and transparent anodes sheds light on a new avenue to construct low-cost and efficient fabric-based devices, showing great potential applications in emerging smart flexible/wearable electronics.

Preparation of fabric-based electronic device via surface topological modification and enzymatic polymerization for personal thermal management, subtle motion detection, and ultraviolet protection

With the increasingly severe problem of population aging, human motion detection and personal thermal management have attracted widespread attention in the field of smart wearable electronics. However, the current multifunctional flexible devices face problems, such as lower stability and poor comfort, which greatly hinder their further development. In this work, an improved fabrication strategy combining in situ enzymatic polymerization and surface topological modification is proposed to facile and efficiently prepare poly(3,4-ethylenedioxythiophene)/polyacrylamide (PEDOT/PAAm) smart fabric. To increase the conductivity and the bonding force between fabric and PEDOT particles, the PAAm was used to pre-construct a microgel layer on the surface of cotton fabric to make PEDOT uniformly coated on the fabric, thus forming a highly electrically conductive interconnection network. The resulting fabric samples show outstanding duel-driven thermal performance (88.6 °C for 2 sun, 84.5 °C for 10 V), satisfactory detection capability for subtle and rapid motion (drops of water and paper pill, bending of fingers), and remarkable ultraviolet protection performance (24.6 times than the UPF value of unmodified fabric sample). All in all, multifunctional fabric-based devices with remarkable performance exhibited great application potential in rehabilitation therapy and personal home care, especially for people with disabilities and older people.

Multifunctional hydrophobic fabric-based strain sensor for human motion detection and personal thermal management

• Sensors with multifunctional biomedical applications are rational designed and fabricated. • The developed PDMS treatment enhances sensor's durability and stability. • The smart fabric has excellent photothermal and Joule-thermal performance as thermal management device. • Benefit from good anti-wetting and photothermal property, smart fabric exhibits superior de-icing ability. Multifunctional flexible devices for human motion detection and thermal management raised great attention as the problem of the aging population is becoming more and more serious. However, it is still a challenge to endow the devices with excellent stability and wide application scope. Here we prepared a hydrophobic and conductive fabric-based strain sensor for smart fabric via successively coating with polydopamine (PDA), polyaniline (PANI), polypyrrole (PPy), and polydimethylsiloxane (PDMS) through in-situ polymerization and dip-coating, which could be used for strain sensor and wearable heater both in air and underwater. The obtained sample exhibited a fast electrical response in 500 ms and could withstand 10000 times stretching-releasing cycles, additionally, the sample exhibited satisfactory electro-thermal and photo-thermal performances. As a whole, the multifunctional fabric-based devices with excellent performances show great potential to be applied in medical monitoring and personal care, especially for aged and disabled persons.

MotorSkins—a bio-inspired design approach towards an interactive soft-robotic exosuit

The work presents a bio-inspired design approach to a soft-robotic solution for assisting the knee-bending in users with reduced mobility in lower limbs. Exosuits and fluid-driven actuators are fabric-based devices that are gaining increasing relevance as alternatives assistive technologies that can provide simpler, more flexible solutions in comparison with the rigid exoskeletons. These devices, however, commonly require an external energy supply or a pressurized-fluid reservoir, which considerably constrain the autonomy of such solutions. In this work, we introduce an event-based energy cycle (EBEC) design concept, that can harvest, store, and release the required energy for assisting the knee-bending, in a synchronised interaction with the user and the environment, thus eliminating any need for external energy or control input. Ice-plant hydro-actuation system served as the source of inspiration to address the specific requirements of such interactive exosuit through a fluid-driven material system. Based on the EBEC design concepts and the abstracted bio-inspired principles, a series of (material and process driven) design experimentations helped to address the challenges of realising various functionalities of the harvest, storage, actuation and control instances within a closed hydraulic circuit. Sealing and defining various areas of water-tight seam made out of thermoplastic elastomers provided the base material system to program various chambers, channels, flow-check valves etc of such EBEC system. The resulting fluid-driven EBEC-skin served as a proof of concept for such active exosuit, that brings these functionalities into an integrated ‘sense-acting’ material system, realising an auto-synchronised energy and information cycles. The proposed design concept can serve as a model for development of similar fluid-driven EBEC soft-machines for further applications. On the more general scheme, the work presents an interdisciplinary design-science approach to bio-inspiration and showcases how biological material solutions can be looked at from a design/designer perspective to bridge the bottom–up and top–down approach to bio-inspiration.

A Warp-Knitted Light-Emitting Fabric-Based Device for In Vitro Photodynamic Therapy: Description, Characterization, and Application on Human Cancer Cell Lines.

Simple SummaryWhile photodynamic therapy appears to be a promising approach to treating cancers, the complexity of its parameters prevents wide acceptance. Accurate light dose measurement is one of the keys to photodynamic effect assessment, but it remains challenging when comparing different technologies. This work provides a complete demonstration of the technical performance of a homemade optical device, based on knitted light-emitting fabrics, called CELL-LEF. Thermal and optical distributions and related safeties are investigated. The results are discussed in relation to the requirements of photodynamic therapy. The usability of CELL-LEF is investigated on human cancer cell lines as a proof of concept. This study highlights that new light-emitting fabric-based technologies can be relevant light sources for in vitro photodynamic therapy studies of tomorrow.Photodynamic therapy (PDT) appears to be a promising strategy in biomedical applications. However, the complexity of its parameters prevents wide acceptance. This work presents and characterizes a novel optical device based on knitted light-emitting fabrics and dedicated to in vitro PDT involving low irradiance over a long illumination period. Technical characterization of this device, called CELL-LEF, is performed. A cytotoxic study of 5-ALA-mediated PDT on human cancer cell lines is provided as a proof of concept. The target of delivering an irradiance of 1 mW/cm2 over 750 cm2 is achieved (mean: 0.99 mW/cm2; standard deviation: 0.13 mW/cm2). The device can maintain a stable temperature with the mean thermal distribution of 35.1 °C (min: 30.7 °C; max: 38.4 °C). In vitro outcomes show that 5-ALA PDT using CELL-LEF consistently and effectively induced a decrease in tumor cell viability: Almost all the HepG2 cells died after 80 min of illumination, while less than 60% of U87 cell viability remained. CELL-LEF is suitable for in vitro PDT involving low irradiance over a long illumination period.

Horizontally structured microbial fuel cells in yarns and woven fabrics for wearable bioenergy harvesting

Integration of advanced microbial fuel cell technology with conventional textile processes enables the emergence of wearable bioenergy harvesting techniques fueled by human sweat. However, without a standardized architecture for the fabrication of textile microbial fuel cells, large-scale energy harvesting from the human body with smart textiles remains elusive. In this work, a revolutionary device structure for wearable microbial fuel cells is easily built up on 1-D yarns and on 2-D and 3-D woven fabrics. The microbial fuel cell is horizontally structured on an intrinsic non-conductive yarn where the anodic and the cathodic components are formed between the pristine regions of the yarn as an ion exchange channel. The horizontally structured device in the 1-D yarn is easily scaled up to produce more power by connecting multiple yarn devices in series and parallel. The concept of the horizontally structured microbial fuel cell is extended to 2-D and 3-D wearable textiles by weaving functional yarns. The 1-D yarn device inoculated with Shewanella oneidensis MR-1 produced a maximum power of 452 μA/cm3 and a current density of 47.2 μW/cm3, which are greater than other flexible microbial fuel cells. The 2-D/3-D fabric-based devices improved the output performance enough to power an electrical calculator.

Development of fabric-based microfluidic devices by wax printing

Fabric has emerged as an alternative to paper for the fabrication of microfluidic devices. Fabric could be easily manufactured using various natural and synthetic materials that contain a wide variety of functional groups, which can participate in binding to different types of molecules without further functionalization. To allow a rapid fabrication of more sophisticated fabric-based devices, we demonstrate that a commercial wax printer can be used to print 2D and 3D devices on fabric, followed by melting wax into fabric with heat treatment. The heating temperature and time were optimized to create the devices. The relationship between the width of the originally printed lines and the formed hydrophobic barriers was also investigated. The developed microfluidic fabric-based analytical devices show great potentials for real-life applications using colorimetric assay.

Integrated wax valve for robust fluid control in an electrochemical fabric-based device.

Although fabrics have great promise as substrates for use in wearable precision health applications, there has been relatively little attention focused on the development of control tools suitable for use in fabrics. Fluid control tools in fabric would enable the automation of multi-step sample processing on the device, reducing the need for off-chip sample handling. In this study, we describe the operation and characterization of a wax-based valving method with an integrated resistive heater in fabric for automated fluid delivery. The combination of wax-transfer-printed wax barrier and stencil-printed conductive ink heating element in fabric is a novel approach for achieving fluid control. We demonstrate robust valve operation and a rapid valve response time, and quantify the reproducibility of fluid flow through replicate valves. Further, we characterize wax redistribution in fabric using optical methods and scanning electron microscope imaging. Finally, we demonstrate valve utility in the context of on-device incubation in a fabric-based device for electrochemical glucose sensing. With a fabrication method that is compatible with a variety of substrates, this valving method has broad applicability.