Wearable devices

Wearable Devices and Wireless Networks Tools for Pervasive Health Care In-Life Testing... 

Sensoria Body-sensing wearable devices with integrated e-textile All the data from the jjroducts are collected in a... 

From the perspective of physical interaction, mobile form factors present interaction design challenges, including restricted display space and input mechanisms, function integration, management of multiple communication channels, and reduced computing power. When viewed from a broader user experience perspective, mobile devices are cultural accessories and must fit with the user s aesthetics and personality. Wearable devices must be comfortable emotionally as well as physically for the wearer, similar to the impact of an accessory to clothing. 

Solar cells can directly convert solar energy into electricity, which is clean and inexhaustible. Generally, the solar cells are built with a planar sandwiched structure on the rigid substrate, which restricts their applications in many fields. Flexible polymer substrates, such as poly(ethyleneterephthalate) (PET), poly(ethylenenaphthalate) (PEN), and polydimeth-ylsiloxane (PDMS), have been widely used to fabricate flexible solar cells. With high stability and flexibility, the solar cells can easily integrate with other portable or wearable devices to significantly extend their applications. 

In summary, a variety of flexible energy harvesting devices including solar cells and piezoelectric devices have been developed to meet the requirement of next-generation portable or wearable devices. However, the power conversion efficiencies of electronic devices were largely limited by the high electrical resistance of flexible electrodes based on polymer substrates. Therefore, more efforts are required to develop new flexible electrodes with higher electrical conductivities. 

Knight et al. (2002) developed a comfort assessment tool considering six dimensions, which cover both physical and emotional aspects of comfort. They found that concerns about the appearance of a wearable device, concerns about a device being active when performing certain tasks, and not feeling secure were negatively linked to emotional and anxiety dimensions and hence influenced perceived comfort levels. 

Two common piezoelectric materials are polymers (polyvinylidene fluoride, PVDF) and c mics (lead zirconate titanate, PZT). The polymer materials are soft and flexible however have lower dielectric and piezoelectric properties than ceramics. Conventional piezoelectric ceramic materials are rigid, heavy and can only be produced in block form. Ceramic materials add additional mass and stiffiiess to the host structure, especially when working with flexible/lightweight materials. This and their fragile nature limit possibilities for wearable devices. Comparisons of several piezoelectric materials are presented in Table 1. 

Wearable devices will undoubtedly multiply in years to come due to a constant decrease in size and power requirements of electronic systems. Batteries will therefore present numerous problems, mainly their bulky size and the ct that they need to be periodically rqilaced or recharged. Piezoelectric materials respond to almost any type and magnitude of physical stimulus, including but not limited to pressure, tensile force, and torsion. One wearable application embedded a piezoelectric material into a shoe to genoate power fonn walking. ... 

Thiruvengada, H., Srinivasan, S., and Gacic, A., Design and implementation of an automated human activity monitoring application for wearable devices. IEEE Int. Conf. Syst. Man Cybern., IEEE, 2008, pp. 2252-2258,2008. 

White, K., Spray, R., Horn, Q., May 2014. Wearable devices integrating textiles, electronics and portable power. In Techtextil North America Conference, Atlanta, GA, USA. 

The power assist glove from Okayama University, Japan, comprises six pneumatic mbber (possibly based on braided structures) muscles secured to an ordinary glove (Sasaki et al., 2004). The muscles achieve approximately 20 N, which is sufficient to interact with objects in daily life. Some studies show the possibihty to use PAM to design devices for walking assistance (Kanno et al., 2015) or low back support (Li et al., 2013). Of course, it is possible to propose an entire wearable device like the Muscle Suit from Tokyo University (Kobalob). The main interest in this is that this muscle suit is wearable and does not consist of a metal frame with artificial muscles. The suit is only attached to the body with a belt and Velcro. 

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