Smart Bandage Research Articles

Stretchable, flexible and breathable polylactic acid/polyvinyl pyrrolidone bandage based on Kirigami for wounds monitoring and treatment

Chronic wounds are slow to recover. During treatment, the dressing needs to be removed to check the recovery status, a process that often results in wound tears. Traditional dressings lack stretching and flexing properties and are not suitable using on wounds in joints, which require movement from time to time. In this study, we present a stretchable, flexible and breathable bandage consisting of three layers, including Mxene coating on the top, the polylactic acid/polyvinyl pyrrolidone (PLA/PVP) layer designed as Kirigami in the middle, and the f-sensor at the bottom. By the way, the f-sensor is in contact with the wound sensing real-time microenvironmental changes due to infection. When the infection intensifies, the Mxene coating at the top is utilized to enable anti-infection treatment. And Kirigami structure of PLA/PVP ensures that this bandage has stretchability, bendability, and breathability. The stretch of the smart bandage increases to 831 % compared to the original structure, and the modulus reduces to 0.04 %, which adapts extremely well to the movement of the joints and relieves the pressure on the wound. This monitoring-treatment closed-loop working mode, eliminating the need to remove dressings and avoid tissue tearing, shows a promising capability in the field of surgical wound care.

Smart Bandaid Integrated with Fully Textile OECT for Uric Acid Real-Time Monitoring in Wound Exudate

Hard-to-heal wounds (i.e., severe and/or chronic) are typically associated with particular pathologies or afflictions such as diabetes, immunodeficiencies, compression traumas in bedridden people, skin grafts, or third-degree burns. In this situation, it is critical to constantly monitor the healing stages and the overall wound conditions to allow for better-targeted therapies and faster patient recovery. At the moment, this operation is performed by removing the bandages and visually inspecting the wound, putting the patient at risk of infection and disturbing the healing stages. Recently, new devices have been developed to address these issues by monitoring important biomarkers related to the wound health status, such as pH, moisture, etc. In this contribution, we present a novel textile chemical sensor exploiting an organic electrochemical transistor (OECT) configuration based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for uric acid (UA)-selective monitoring in wound exudate. The combination of special medical-grade textile materials provides a passive sampling system that enables the real-time and non-invasive analysis of wound fluid: UA was detected as a benchmark analyte to monitor the health status of wounds since it represents a relevant biomarker associated with infections or necrotization processes in human tissues. The sensors proved to reliably and reversibly detect UA concentration in synthetic wound exudate in the biologically relevant range of 220-750 μM, operating in flow conditions for better mimicking the real wound bed. This forerunner device paves the way for smart bandages integrated with real-time monitoring OECT-based sensors for wound-healing evaluation.

Wearable battery-free smart bandage with peptide functionalized biosensors based on MXene for bacterial wound infection detection

Wound infection is a life-threatening healthcare issue that can cause severe pain, sepsis, and even amputation. Herein, to address the challenges of point-of-care wound analysis, a battery-free, wireless, and wearable smart bandage was developed for bacterial virulence factors detection. Typical biomarkers, sortase A and pyocyanin, corresponding to two major types of bacterial infection, Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, were detected with electrochemical differential pulse voltammetry. Ti3C2Tx MXene was applied to the electrode to enhance the sensitivity. Pyocyanin could transfer electrons with the electrode for sensing due to its redox characteristics, while a peptide labeled with the electroactive ferrocene was customized for the specific recognition of sortase A. The integration of near field communication module realized wireless energy harvesting and data transmission with the smartphone. The fully integrated system demonstrated good linearity and high sensitivity, with wide detection ranges of 1 pg/mL to 100 ng/mL for sortase A, and 1 μM to 100 μM for pyocyanin. Furthermore, the animal studies indicated the effectiveness of the smart bandage for multi-biomarker profiling of wound. This wearable system provides a noninvasive, convenient, and efficient platform for in situ bacterial virulence factors detection, offering great potential for the management of the infected wound.

Stretchable self-adhesive and self-powered smart bandage for motion perception and motion intention recognition

The research on flexible and stretchable self-powered sensors perceiving human body motion and physiological signals has become a hot spot in recent years. Aided with machine learning, more features of the human motion and physiological signals can be intelligently interpreted. Here, we first propose a triboelectric nanogenerator (BMS-TENG) based on highly conductive multi-walled carbon nanotubes, flexible and stretchable silica gel, and a self-adhesive elastic bandage, which is highly stretchable and self-adhesive for easy fixation on the skin. The maximum stretchability of the sensor is 502%. BMS-TENG sensor can collect a variety of human motion and physiological signals, such as bending fingers and elbows, lifting legs, breathing, and swallowing. With the support of machine learning, we propose a smart bandage system capable of acquiring motion signals and recognizing intentions. By collecting signals from the forearm near the elbow instead of the fingers, the smart bandage can recognize various gestures and muscle action features. Applications of intention-manipulating diverse gestures from the robotic hand and individual identification work well. The system has great potential in human motion monitoring, electronic skin, human-computer interaction, gesture recognition, biomedicine, and other fields.

Smart Polymeric Wound Dressing for Treating Partial-Thickness Burns: A Preliminary Preclinical Study on the Porcine Model

Several so-called “smart” dressings are available for burn injuries to promote faster wound healing, and this technology has recently reported substantial advancements. However, the selection of an appropriate dressing for partial-thickness burns requires consideration of several crucial elements, including exudate management, conformability, antimicrobial properties, ease of application and removal, patient comfort, and cost-effectiveness. This preliminary feasibility study uses a porcine model to test the INTELIGELS product (Smart Bandage) for partial-thickness burns treatment. Artificially made wounds, mimicking partial-thickness burns, were assessed in two studies with and without antimicrobial additives, where wounds were randomly assigned to the experimental group treated with Smart Bandage and two control groups treated with a simple saline gauze dressing or Aquacel® products with and without silver additives. In addition, all dressings were evaluated for their ability to reduce wound size, quantified by histological analysis using punch biopsies. This study demonstrates comparable healing properties of Smart Bandage and Aquacel® dressings that are superior to the simple saline gauze dressing. The superiority is demonstrated by better regeneration, less inflammation of the epidermis and dermis, and better dermis remodeling with more granulation tissue maturation within the wound area when Smart Bandage/Aquacel® dressings are applied as compared with the simple gauze dressing.

Soft, Wireless Pressure‐Sensor‐Integrated Smart Bandage for the Management of Diabetic Foot Ulcers

AbstractDiabetic foot ulcers (DFUs) have affected millions of people in the U.S. and posed heavy burden to patients and the healthcare system due to their being slow to heal, high recurrence rate, and potential risk of amputation and even premature death. A mainstay of DFU therapy is mechanical offloading to mitigate pressure at the ulcer, which, however, is usually not effective due to patients’ diminished sensation capabilities on the foot and low adherence to offloading recommendations. This work reports a soft, flexible, wireless pressure‐sensor‐integrated smart bandage system for continuously monitoring the pressure on the foot and alerting the users to offload under exceeded pressure. The pressure sensor exhibits high linearity, negligible hysteresis, fast response time, and excellent water‐proof properties relevant for this application. Wireless data transmission onto a smartphone via Bluetooth enables the display and interpretation of the measured pressure with the option of a preset pressure threshold, when exceeded, an alert will be generated for immediate notifications. Trials on healthy subjects demonstrate reliable monitoring performance. The developed smart bandage system represents a significant advance in the prevention and management of DFUs and other pressure injuries as well as compression therapy corrections.

Wireless, closed-loop, smart bandage with integrated sensors and stimulators for advanced wound care and accelerated healing.

'Smart' bandages based on multimodal wearable devices could enable real-time physiological monitoring and active intervention to promote healing of chronic wounds. However, there has been limited development in incorporation of both sensors and stimulators for the current smart bandage technologies. Additionally, while adhesive electrodes are essential for robust signal transduction, detachment of existing adhesive dressings can lead to secondary damage to delicate wound tissues without switchable adhesion. Here we overcome these issues by developing a flexible bioelectronic system consisting of wirelessly powered, closed-loop sensing and stimulation circuits with skin-interfacing hydrogel electrodes capable of on-demand adhesion and detachment. In mice, we demonstrate that our wound care system can continuously monitor skin impedance and temperature and deliver electrical stimulation in response to the wound environment. Across preclinical wound models, the treatment group healed ~25% more rapidly and with ~50% enhancement in dermal remodeling compared with control. Further, we observed activation of proregenerative genes in monocyte and macrophage cell populations, which may enhance tissue regeneration, neovascularization and dermal recovery.

Healing chronic wounds with a wireless smart bandage with integrated sensors and stimulators.

Healing chronic wounds with a wireless smart bandage with integrated sensors and stimulators.

Bioengineered and functionalized silk proteins accelerate wound healing in rat and human dermal fibroblasts.

Wound healing is an intrinsic process directed towards the restoration of damaged or lost tissue. The development of a dressing material having the ability to control the multiple aspects of the wound environment would be an ideal strategy to improve wound healing. Though natural silk proteins, fibroin, and sericin have demonstrated tissue regenerative properties, the efficacy of bioengineered silk proteins on wound healing is seldom assessed. Furthermore, silk proteins sans contaminants, having low molecular masses, and combining with other bioactive factors can hasten the wound healing process. Herein, recombinant silk proteins, fibroin and sericin, and their fusions with cecropin B were evaluated for their wound-healing effects using in vivo rat model. The recombinant silk proteins demonstrated accelerated wound closure in comparison to untreated wounds and treatment with Povidone. Among all groups, the treatment with recombinant sericin-cecropin B (RSC) showed significantly faster healing, greater than 90% wound closure by Day 12 followed by recombinant fibroin-cecropin B (RFC) (88.86%). Furthermore, histological analysis and estimation of hydroxyproline showed complete epithelialization, neovascularization, and collagenisation in groups treated with recombinant silk proteins. The wound healing activity was further verified by in vitro scratch assay using HADF cells, where the recombinant silk proteins induced cell proliferation and cell migration to the wound area. Additionally, wound healing-related gene expression showed recombinant silk proteins stimulated the upregulation of EGF and VEGF and regulated the expression of TGF-β1 and TGF-β3. Our results demonstrated the enhanced healing effects of the recombinant silk fusion proteins in facilitating complete tissue regeneration with scar-free healing. Therefore, the recombinant silks and their fusion proteins have great potential to be developed as smart bandages for wound healing.

Smart Bandage to Monitor Combat Wounds and Control Bacterial Infections During Military Operations

In the United States Army, nearly 50% of soldiers experience 1 or more injuries a year during deployment and mission operations. The most common injuries during these operations can be classified between saturable wounds, such as lacerations and punctures, and non-saturable wounds, such as blast wounds, gunshot wounds, head injuries, bone fractures, burns, and ulcers. In all cases, the leading post-wound treatment are complications associated with wound infections; with sepsis being the leading cause of death in after wound care. Gram-positive, gram-negative, and fungal infections are the most prevalent types of infections seen in the U.S. Army, with Staphylococcus aureus (s. aureus) being the most common infection recorded in about 20% of soldiers. Present techniques are limited to using pressure pads and antibacterial gels for preventing infections. These approaches cannot be integrated into a wearable construct and do not offer a reliable method of management. Therefore, monitoring and treating infection in combat wounds is a major healthcare challenge in wound care management for army application.Our work focuses on developing a wearable smart bandage that can detect a change in pH and lactate using an electrochemical sensing approach that responds as a function of bacterial infection and can monitor in real-time using data generated by sensors. Further, the pH sensing causes a triggered release of drug molecules that control bacterial infection in the wound bed. The electrochemical pH sensors were fabricated by printing commercial flexible inks onto a stretchable thermoplastic polyurethane (TPU, TE-11C DuPontTM) film, and subsequently heat laminating over a cotton gauze (thickness: 100 μm). A conventional three-electrode cell assembly consisting of SPCE, Ag/AgCl as a reference electrode, and a Pt wire as a counter electrode was used for the experiments. CV was performed to assess the performance of the electrodeposited polyaniline. The measurements were performed at a scan rate of 0.02 V s-1 in a potential window of 1 V and -0.2 V. Sensor stability was characterized under room temperature and physiological conditions (RT) over 3 days. In case of the triggered drug release, we synthesized chitosan-pH responsive polymer using an ionic gelation process and drug ampicillin and kanamycin were encapsulated with a 64% efficiency. The polymer released drug above pH 6.5 which correlated to 105 bacterial CFU/ml, thus was incorporated in the bandage matrix and served as a controlled release when infection occurs. It was observed that pH tends to rise as infection progress therefore ideal for drug release in an alkaline environment.Finally, the sensor was able to detect bacterial cells ranging from 102-105 cells and the drug release showed an 82% reduction in cell number. The work carried out highlights an integrated sensor to sense bacterial infections and simultaneously trigger drug release. In light of current findings, this study allowed us to understand the dynamic interaction occurring between the sensor surface and wound bed and the sensor data showed a direct correlation to bacterial infection. The sensor can be integrated into a multiplex wearable device detecting different biomarkers to simultaneously monitor and manage infection in combat as well as chronic wounds.

Wound-Dressing-Based Antenna Inkjet-Printed Using Nanosilver Ink for Wireless Medical Monitoring.

In this paper, we present a wound-dressing-based antenna fabricated via screen-printed and inkjet-printed technologies. To inkjet print a conductive film on wound dressing, it must be screen-printed, UV-curable-pasted, and hard-baked to provide appropriate surface wettability. Two passes were UV-curable-pasted and hard-baked at 100 °C for 2 h on the wound dressing to obtain 65° WCA for silver printing. The silver film was printed onto the wound dressing at room-tempature with 23 μm droplet spacing for three passes, then sintered at 120 °C for 1 h. By optimizing the inkjet printing conditions by modifying the surface morphologies and electrical properties, three-pass printed silver films with 3.15 μm thickness and 1.05 × 107 S/m conductivity were obtained. The insertion losses at the resonant frequency (17 and 8.85 GHz) were −2.9 and −2.1 dB for the 5000 and 10,000 μm microstrip transmission lines, respectively. The material properties of wound dressing with the relative permittivity and loss-tangent of 3.15–3.25 and 0.04–0.05, respectively, were determined by two transmission line methods and used for antenna design. A quasi-Yagi antenna was designed and implemented on the wound-dressing with an antenna bandwidth of 3.2–4.6 GHz, maximal gain of 0.67 dBi, and 42% radiation efficiency. The bending effects parallel and perpendicular to the dipole direction of three fixtures were also examined. The gain decreased from 0.67 to −1.22 dBi and −0.44 dBi for a flat to curvature radius of 5 cm fixture after parallel and perpendicular bending, respectively. Although the maximal gain was reduced with the bending radius, the directivity of the radiation pattern remained unchanged. The feasibility of a wound-dressing antenna demonstrates that inkjet-printed technology enables fast fabrication with low cost and environmental friendliness. Additionally, inkjet-printed technology can be combined with sensing technology to realize remote medical monitoring, such as with smart bandages, for assessment of chronic wound status or basic physical conditions.

Emerging Strategies Based on Sensors for Chronic Wound Monitoring and Management

Pressure ulcers (PUs) are a serious global health challenge, affecting a large section of the population and putting immense pressure on healthcare systems. Sensor-based diagnostic tools and monitoring systems have emerged as a potential non-invasive solution to reduce the occurrence of new cases of PUs and promise a significant reduction in treatment expenditure and time. In this endeavour, the present manuscript reviews the advancements made in the last decade in the development and commercial adoption of different sensor systems for PU-associated chronic wound management. Different types of smart sensor systems have been developed in which pressure, chemical, and optical sensors have witnessed a lot of interest and significant advancement among research communities and industries alike. These sensors utilize a host of nanomaterial-based sensing materials, flexible support, diverse transducing modes, and different device designs to achieve high sensitivity and selectivity for skin pressure, temperature, humidity, and biomarkers released from the wound. Some of these sensor’s array-based electronic skin (e-skin) has reached the stage of commercialization and is being used in commercial products, such as smart bandages, shoes, watches, and mattress among others. Nonetheless, further innovations are necessary in the direction of associating multiple types of sensor arrays, particularly pressure and chemical sensor-based e-skins in a microsystem for performing real-time assessment of all the critical wound parameters.

Automatic Control of Microfluidic Flow Using Natural H ydrogels

Objectives: To explore the effectivity of natural hydrogels for controlling the microfluidic flow in smart bandages. Worldwide, several researchers are trying to develop smart bandage having the capabilities of controlled amount of automatic drug flow to the wound, but the complexity of the required mechatronics does not allow the size of the bandage to be easily wearable. Method: The drug flow within the microchannels of the bandage is controlled using easily available hydro sensitive seeds (Plantago ovato and Salvia hispanica L). On placing the seeds within the microchannels, the investigations showed that the water content within the drug is slowly absorbed by the seeds and the flow of drug is restricted within the channel leading to the controlled flow in a small passage of time. Findings: Plantago ovato and Salvia hispanica L. as natural hydrogels show effective control of the flow rate required for smart bandages. The analysis of the results shows that Salvia hispanica L. can efficiently be used for controlling the drug flow within the microchannels and Plantago ovato for absorbing residue within the sink of the bandage. Novelty: The main problem of the smart bandages developed in some of the labs is the complexity of the design used for controlling the drug flow. The novelty of the proposed smart bandage is its low cost design and efficiency of automatic regulating drug flow without the use of complicated electronics. Keywords: Hydrogels; fluid control; microfluidic; drug reservoir; smart bandage

Improving disease prevention, diagnosis, and treatment using novel bionic technologies.

Increased human life expectancy, due in part to improvements in infant and childhood survival, more active lifestyles, in combination with higher patient expectations for better health outcomes, is leading to an extensive change in the number, type and manner in which health conditions are treated. Over the next decades as the global population rapidly progresses toward a super-aging society, meeting the long-term quality of care needs is forecast to present a major healthcare challenge. The goal is to ensure longer periods of good health, a sustained sense of well-being, with extended periods of activity, social engagement, and productivity. To accomplish these goals, multifunctionalized interfaces are an indispensable component of next generation medical technologies. The development of more sophisticated materials and devices as well as an improved understanding of human disease is forecast to revolutionize the diagnosis and treatment of conditions ranging from osteoarthritis to Alzheimer's disease and will impact disease prevention. This review examines emerging cutting-edge bionic materials, devices and technologies developed to advance disease prevention, and medical care and treatment in our elderly population including developments in smart bandages, cochlear implants, and the increasing role of artificial intelligence and nanorobotics in medicine.

Intelligent Wearable Sensors Interconnected with Advanced Wound Dressing Bandages for Contactless Chronic Skin Monitoring: Artificial Intelligence for Predicting Tissue Regeneration.

Toward the adoption of artificial intelligence-enabled wearable sensors interconnected with intelligent medical objects, this contactless multi-intelligent wearable technology provides a solution for healthcare to monitor hard-to-heal wounds and create optimal efficiencies for clinical professionals by minimizing the risk of disease infection. This article addressed a flexible artificial intelligence-guiding (FLEX-AI) wearable sensor that can be operated with a deep artificial neural network (deep ANN) algorithm for chronic wound monitoring via short-range communication toward a seamless, MXENE-attached, radio frequency-tuned, and wound dressing-integrated (SMART-WD) bandage. Based on a supervised training set of on-contact pH-responsive voltage output, the confusion matrix for healing-stage recognition from this deep ANN machine learning revealed an accuracy of 94.6% for the contactless measurement. The core analytical design of these smart bandages integrated wound dressing of poly(vinyl acrylic) gel@PANI/Cu2O NPs for instigating pH-responsive current during the wound healing process. Effectively, a chip-free bandage tag was fabricated with a capacitive Mxene/PTFE electret and adhesive acrylic inductance to match the resonance frequency generated by the intelligent wearable antenna. Under zero-current electrochemical potential, the wound dressing attained a slope of -76 mV/pH. With the higher activation voltage applied toward the wound dressing electrodes, cuprous ions intercalated more into the hybrid PVA gel/PANI shell, resulting in an exponential increase of the two-terminal current response. The healing phase diagram was classified into regimes of fast-curing, slow-curing, and no-curing for skin disease treatment with corticosteroids. Ultimately, the near-field sensing technology offers adequate information for guiding treatment decisions as well as drug effectiveness for wound care.

“Smart Bandage” May Accelerate Treatment of Chronic Wounds

“Smart Bandage” May Accelerate Treatment of Chronic Wounds

An Absorbent, Flexible, Transparent, and Scalable Substrate for Wound Dressings

Objective: Wound dressings that create and maintain a moist environment provide the optimal conditions for wound healing by increasing the rate of epithelialization and angiogenesis. However, current wound dressings require periodic removal which exposes the wound to the surrounding environment, thereby increasing the likelihood for infection and drying out the wound itself. There remains an unmet medical need for the development of an absorbent, flexible, and transparent wound dressing that can conform to the irregular geometry of the wound for a long-term duration. Herein, we report the development of AFTIDerm, an Absorbent, Flexible, Transparent, and Inexpensive moisture-management wound dressing using Polyvinyl alcohol (PVA) as the host material. Methods: AFTIDerm substrates of varying glycerol concentrations (1 wt%, 3 wt%, 5 wt%, 7 wt%, and 10 wt%) were fabricated and tested. The mechanical, absorption, and biological properties of AFTIDerm were evaluated. Results: We found that 5% glycerol served as the optimal concentration for AFTIDerm. The biocompatibility, absorptive capabilities, and scalability render PVA/glycerol an ideal material composition for wound dressings. Benchtop experimentation and pre-clinical testing demonstrate AFTIDerm as a platform for use in wound dressings. Discussion/Conclusion: The development of AFTIDerm broadens the translational utility of this materials platform not only as a material for wound dressings to minimize dressing changes in low to moderate exudate environments, but also as a potential substrate material for smart bandages. Clinical and Translational Impact Statement— AFTIDerm, an absorbent, flexible, and transparent wound dressing, maintains the moist environment required for healing while enabling monitoring of healing without removal and disruption to the wound bed.

Deacetylated cellulose acetate nanofibrous dressing loaded with chitosan/propolis nanoparticles for the effective treatment of burn wounds

Every year, about 1 out of 9 get burnt in Egypt, with a mortality rate of 37%, and they suffer from physical disfigurement and trauma. For the treatment of second-degree burns, we aim at making a smart bandage provided with control of drug release (using chitosan nanoparticles) to enhance the healing process. This bandage is composed of natural materials; namely, cellulose acetate (CA), chitosan, and propolis (bee resin) as the loaded drug. Cellulose acetate nanofibers were deacetylated by NaOH after optimizing the reaction time and the concentration of NaOH solution, and the product was confirmed with FTIR analysis. Chitosan/propolis nanoparticles were prepared by ion gelation method with size ranging from 100 to 200 nm and a polydispersity index of 0.3. Chitosan/propolis nanoparticles were preloaded in the CA solution to ensure homogeneity. Loaded deacetylated cellulose nanofibers have shown the highest hydrophobicity measured by contact angle. Cytotoxicity of propolis and chitosan/propolis nanoparticles were tested and the experimental IC50 value was about 137.5 and 116.0 μg/mL, respectively, with p-value ≤0.001. In addition, chitosan/propolis nanoparticles loaded into cellulose nanofibers showed a cell viability of 89.46% in the cell viability test. In-vivo experiments showed that after 21 days of treatment with the loaded nanofibers repairing of epithelial cells, hair follicles and sebaceous glands in the skin of the burn wound were found in albino-mice model.

Recent advances in 3D printing technologies for wearable (bio)sensors

Wearable (bio)sensors driven through emerging three-dimensional (3D) printing technologies are currently considered the next-generation tools for various healthcare applications due to their exciting characteristics such as high stretchability, super flexibility, low cost, ultra-thinness, and lightweight. In this context, 3D printing, an emerging advanced additive manufacturing technology has revolutionized the concept of free form construction and end-user customization owing to its multifarious peculiarities that involve ease of operation, on-demand and rapid fabrication, precise and controlled deposition, as well as versatility with various soft functional materials. The customized functional structures with controllable geometry and design can be autonomously printed on the desired surfaces using the 3D printing technologies excluding the prerequisite amenities of microfabrication technologies. To accomplish this, both academics and industry experts have worked persistently to fabricate smaller, faster, and more efficient wearable devices using readily available 3D printing technologies. The contribution of 3D printing technologies in developing novel 3D structures for wearable applications using printable soft and functional materials is highlighted in this article. Moreover, the process of 3D printing along with major techniques, namely vat photopolymerization, material jetting, and material extrusion are summarized. Besides this, a number of 3D printed (bio)sensing platforms such as glucose sensors, lactate sensors, sweat sensors, strain sensors, tactile sensors, wearable oximeters, smart bandages, artificial skin, tattoo sensors, electroencephalography (EEG), electrocardiography (ECG) sensors, etc., are discussed in terms of design specifications and fabrication strategies of devices obtained via 3D printing techniques. Pictorial representation of 3D printed wearable (bio)sensors indicating numerous 3D printing materials (composite filaments, elastomers, functional inks, and hydrogels); techniques (vat photopolymerization, material jetting, and material extrusion), and different applications (glucose biosensing, strain sensing, tactile sensing, sweat sensing, ECG/EEG sensing, etc.) • Explores the recent advances in 3D printing technologies for wearable (bio)sensors. • Soft materials compatible with 3D printing technologies are discussed. • Process of 3D printing and techniques namely vat photopolymerization, material jetting, material extrusion are highlighted. • Potential 3D printed wearable (bio)sensors are reviewed in terms of design specifications and fabrication strategies.

Design of a metamaterial film with excellent conformability and adhesion for bandage substrates

Developing films with excellent conformability and adhesion has become a research hotspot in many fields, such as medical bandages. The conventional method for enhancing films conformability and adhesion is to make the films thinner or modify the material of the films, which usually compromises the function of the films. In this paper, a novel metamaterial film was proposed to cover the skin area of a human elbow during the rotation of elbow. This structure is composed of unit cells with rectangular perforations, whose Poisson's ratio (PR) is determined by the length of the perforation. With finite element analysis (FEA), relations among the stretch strain, Poisson's ratio and length of the perforation of unit cell was obtained. Then, the proposed film was generated by mapping unit cells with different PR to the target skin surface. With the same deformation behavior as the elbow skin, conformability and adhesion of the generated film can be guaranteed during the entire rotation process of the elbow, which has been verified by both FEA and experimental tests. Theoretically, by changing the arrangement of different PR unit cells, the proposed method can be applied to design films for other complex surface on human body. It also provides a new way to introduce materials with better biocompatibility but poor mechanical properties as bandage substrates. As a possible application, a prototype of smart bandage was developed by installing a high-resolution temperature sensor on the proposed film, which can monitor the inflammation of the wounded skin in real time.