With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. However, currently available devices have limits on stretchability, flexibility, portability and high cost because of their functional materials. Therefore, there is a critical need to develop conductive materials that can withstand repeated large strain, pressure and can be manufactured into discreet, low cost, and dense arrays with high stretchability, flexibility, and sensitivity.

This research presents a shape memory polymer embedded highly flexible and stretchable wrinkled carbon nanotube thin film wire. We preassemble CNTs on a shape memory polymer substrate with wrinkles, to demonstrate significant densification, improvement of stretchability and high electrical performance followed by the shrinking of the substrate. And we transferred to Ecoflex or PDMS thin films which utilized as wearable and skin-mountable strain sensor and pressure sensor for human motion and physiological signals detection. Unlike pre-existing sensors, these wrinkled CNT strain and pressure sensors can be worn conformal to human skin and are capable to endure higher strains and pressure. The piezoresistive response of shrink induced wrinkled CNT thin films demonstrated conductive performance in excess of high strain and pressure. Also the wrinkled CNT wires exhibited consistent performance after repetitive stimulus. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible to conventional manufacturing processes. In this proposal, we focus on this wrinkled CNT concept toward practical applications in flexible and highly sensitive sensor for monitoring human physiological signals as wearable sensors which relates to the health of individuals.

Control of Néel vector in antiferromagnetic materials is one of the challenges preventing their use of as active device components. Several methods have been investigated such as exchange bias, electric field, and spin injection, but little is known about strain-meditated anisotropy. This study of antiferromagnetic L10-type MnX alloys MnIr, MnRh, MnNi, MnPd, and MnPt shows that a small amount of strain effectively rotates the direction of the Néel vector by 90⁰ for all of the materials. For MnIr, MnRh, MnNi, and MnPd, the Néel vector rotates within the basal plane. For MnPt, the Néel vector rotates from out-of-plane to in-plane under tensile strain. The effectiveness of strain control is quantified by a metric of efficiency and by direct calculation of the magnetostriction coefficients. The values of the magnetostriction coefficients are comparable with those from ferromagnetic materials. These results indicate that strain is a mechanism that can be exploited for control of the Néel vectors in this family of antiferromagnets. CrSb is a layered antiferromagnet (AFM) with perpendicular magnetic anisotropy, a high Néel temperature, and large spin-orbit coupling (SOC), which makes it interesting for AFM spintronic applications. To elucidate the various mechanisms of Néel vector control, the effects of strain, band filling, and electric field on the magnetic anisotropy energy (MAE) of bulk and thin-film CrSb are determined and analysed using density functional theory. The MAE of the bulk crystal is large (1.2 meV per unit cell). Due to the significant ionic nature of the Cr-Sb bond, finite slabs are strongly affected by end termination. Truncation of the bulk crystal to a thin film with one surface terminated with Cr and the other surface terminated with Sb breaks inversion symmetry, creates a large charge dipole and average electric field across the film, and breaks spin degeneracy, such that the thin film becomes a ferrimagnet. The MAE is reduced such that its sign can be switched with realistic strain, and the large SOC gives rise to an intrinsic voltage controlled magnetic anisotropy (VCMA). A slab terminated on both faces with Cr remains a compensated AFM, but with the compensation occurring nonlocally between mirror symmetric Cr pairs. In-plane alignment of the moments is preferred, the magnitude of the MAE remains large, similar to that of the bulk, and it is relatively insensitive to filling.