A three-dimensional liquid diode for soft, integrated permeable electronics.

Wearable electronics with great breathability enable a comfortable wearing experience and facilitate continuous biosignal monitoring over extended periods1-3. However, current research on permeable electronics is predominantly at the stage of electrode and substrate development, which is far behind practical applications with comprehensive integration with diverse electronic components (for example, circuitry, electronics, encapsulation)4-8. Achieving permeability and multifunctionality in a singular, integrated wearable electronic system remains a formidable challenge. Here we present a general strategy for integrated moisture-permeable wearable electronics based on three-dimensional liquid diode (3D LD) configurations. By constructing spatially heterogeneous wettability, the 3D LD unidirectionally self-pumps the sweat from the skin to the outlet at a maximum flow rate of 11.6 ml cm-2 min-1, 4,000 times greater than the physiological sweat rate during exercise, presenting exceptional skin-friendliness, user comfort and stable signal-reading behaviour even under sweating conditions. A detachable design incorporating a replaceable vapour/sweat-discharging substrate enables the reuse of soft circuitry/electronics, increasing its sustainability and cost-effectiveness. We demonstrated this fundamental technology in both advanced skin-integrated electronics and textile-integrated electronics, highlighting its potential for scalable, user-friendly wearable devices.

3D printed auxetic heel pads for patients with diabetic mellitus.

More than 422 million people worldwide suffered from diabetes mellitus (DM) in 2021. Diabetic foot is one the most critical complications resultant of DM. Foot ulceration and infection are frequently arisen, which are associated with changes in the mechanical properties of the plantar soft tissues, peripheral arterial disease, and sensory neuropathy. Diabetic insoles are currently the mainstay in reducing the risk of foot ulcers by reducing the magnitude of the pressure on the plantar Here, we propose a novel pressure relieving heel pad based on a circular auxetic re-entrant honeycomb structure by using three-dimensional (3D) printing technology to minimize the pressure on the heel, thus reducing the occurrence of foot ulcers. Finite element models (FEMs) are developed to evaluate the structural changes of the developed circular auxetic structure upon exertion of compressive forces. Moreover, the effects of the internal angle of the re-entrant structure on the peak contact force and the mean pressure acting on the heel as well as the contact area between the heel and the pads are investigated through a finite element analysis (FEA). Based on the result from the validated FEMs, the proposed heel pad with an auxetic structure demonstrates a distinct reduction in the peak contact force (∼10%) and the mean pressure (∼14%) in comparison to a conventional diabetic insole (PU foam). The characterized result of the designed circular auxetic structure not only provides new insights into diabetic foot protection, but also the design and development of various impact resistance products.

Impact of postural variation on hand measurements: Three-dimensional anatomical analysis.

In this article, the impact of postural variations on hand anthropometry and distribution of skin strain ratios has been investigated. The literature suggests the glove fit directly affects hand functions. However, gloves currently manufactured based on a static posture failed to provide optimum fit. Workers often do not wear protective gloves due to discomfort caused by improper design, which increases the risk of hand injury. Full-color three-dimensional scans of the hands are captured with thirty healthy subjects (20 females, 10 males) to analyze the hand measurements and skin deformation with various postures. 42 of the 57 hand dimensions were found to have significant differences (p >0.05) related to hand posture. The skin strain ratios further suggest that the slant of the web space, dorsal-length and surface area should be increased, while the angles of the web space and length of the palm reduced to advance glove patterns. This research contributes to constructing gloves with optimum fit, performance, and comfort. Results show that in consideration of hand postures, the angle of the slant of web space between digits 2 and 5 and the finger length on the dorsal side should be increased, whilst the finger length on the palm side should be reduced in glove pattern design. Gloves currently constructed based on a splayed posture cannot provide a good fit. Consideration should be given to hand measurements in dynamic postures.

A Novel Bespoke Hypertrophic Scar Treatment: Actualizing Hybrid Pressure and Silicone Therapies with 3D Printing and Scanning.

The treatment of hypertrophic scars (HSs) is considered to be the most challenging task in wound rehabilitation. Conventional silicone sheet therapy has a positive effect on the healing process of HSs. However, the dimensions of the silicone sheet are typically larger than those of the HS itself which may negatively impact the healthy skin that surrounds the HS. Furthermore, the debonding and displacement of the silicone sheet from the skin are critical problems that affect treatment compliance. Herein, we propose a bespoke HS treatment design that integrates pressure sleeve with a silicone sheet and use of silicone gel using a workflow of three-dimensional (3D) printing, 3D scanning and computer-aided design, and manufacturing software. A finite element analysis (FEA) is used to optimize the control of the pressure distribution and investigate the effects of the silicone elastomer. The result shows that the silicone elastomer increases the amount of exerted pressure on the HS and minimizes unnecessary pressure to other parts of the wrist. Based on this treatment design, a silicone elastomer that perfectly conforms to an HS is printed and attached onto a customized pressure sleeve. Most importantly, unlimited scar treating gel can be applied as the means to optimize treatment of HSs while the silicone sheet is firmly affixed and secured by the pressure sleeve.

Customized Fabrication Approach for Hypertrophic Scar Treatment: 3D Printed Fabric Silicone Composite.

Hypertrophic scars (HS) are considered to be the greatest unmet challenge in wound and burn rehabilitation. The most common treatment for HS is pressure therapy, but pressure garments may not be able to exert adequate pressure onto HS due to the complexity of the human body. However, the development of three-dimensional (3D) scanning and direct digital manufacturing technologies has facilitated the customized placement of additively manufactured silicone gel onto fabric as a component of the pressure therapy garment. This study provides an introduction on a novel and customized fabrication approach to treat HS and discusses the mechanical properties of 3D printed fabric reinforced with a silicone composite. For further demonstration of the suggested HS therapy with customized silicone insert, silicone inserts for the finger webs and HS were additively manufactured onto the fabric. Through the pressure evaluation by Pliance X system, it proved that silicone insert increases the pressure exerted to the HS. Moreover, the mechanical properties of the additively manufactured fabric silicone composites were characterized. The findings suggest that as compared with single viscosity print materials, the adhesive force of the additively manufactured silicone and fabric showed a remarkable improvement of 600% when print materials with different viscosities were applied onto elevated fabric.