A Study on Consumers’ Visual Image Evaluation of Wrist Wearables

This study aimed to investigate consumers’ visual image evaluation of wrist wearables based on Kansei engineering. A total of 8 representative samples were screened from 99 samples using the multidimensional scaling (MDS) method. Five groups of adjectives were identified to allow participants to express their visual impressions of wrist wearable devices through a questionnaire survey and factor analysis. The evaluation of eight samples using the five groups of adjectives was analyzed utilizing the triangle fuzzy theory. The results showed a relatively different evaluation of the eight samples in the groups of “fashionable and individual” and “rational and decent”, but little distinction in the groups of “practical and durable”, “modern and smart” and “convenient and multiple”. Furthermore, wrist wearables with a shape close to a traditional watch dial (round), with a bezel and mechanical buttons (moderate complexity) and asymmetric forms received a higher evaluation. The acceptance of square- and elliptical-shaped wrist wearables was relatively low. Among the square- and rectangular-shaped wrist wearables, the greater the curvature of the chamfer, the higher the acceptance. Apparent contrast between the color of the screen and the casing had good acceptance. The influence of display size on consumer evaluations was relatively small. Similar results were obtained in the evaluation of preferences and willingness to purchase. The results of this study objectively and effectively reflect consumers’ evaluation and potential demand for the visual images of wrist wearables and provide a reference for designers and industry professionals.     

Highly Stable Graphene Inks Based on Organic Binary Solvents

Formulating highly stable graphene-based conductive inks with consistency in electrical properties over the storage period has remained a significant challenge in the development of wearable electronics. Two highly stable graphene-based inks (Cyclohexanone:Ethylene glycol (CEG) ink and Cyclohexanone:Terpineol (CT) ink) are prepared by using two different organic binary solvents, for the first time, without using solvent exchange methods. Both the inks display remarkably high stability (stable even after two months) with negligible variability in electrical properties. Here, it is demonstrated how such inks can be utilized to coat flexible substrates to create wearable e-textiles. Both the inks coated e-textiles show significantly low sheet resistance (≈209.1 Ω □⁻¹ for CEG ink and ≈322.4 Ω □⁻¹ CT ink) that show less than a 15% increase in electrical resistance over two months. Therefore, these inks offer high productivity and reproducibility and can be one of the most effective methods for formulating graphene-based inks.     

Multifunctional liquid metal polymer composites

Liquid metal polymer composites are an emerging class of functional materials with potentially transformative impacts in wearable electronics, soft robotics, and human-computer interactions. By employing different processing methods, room temperature liquid metal inclusions can be embedded in insulating polymers like elastomers to incorporate functional properties of metals while the matrix remains soft and stretchable. These solid–liquid composites offer an interesting, yet complex multifunctional material system. In this review, we present an exclusive overview of the synthesis methods, structural and functional properties, and applications of gallium-based liquid metal polymer composites. Common methods to control the size of liquid metal inclusions and their interaction in polymers are discussed. Moreover, the effect of liquid metal microstructures on the overall properties of the composites is summarized. We also highlight the new trends in terms of material composition, printing process, and novel applications of liquid metal polymer composites in intelligent systems.