Geometrically engineered rigid island array for stretchable electronics capable of withstanding various deformation modes

Abstract

Integration of rigid components in soft polymer matrix is considered as the most feasible architecture to enable stretchable electronics. However, a method of suppressing cracks at the interface between soft and rigid materials due to excessive and repetitive deformations of various types remains a formidable challenge. Here, we geometrically engineered Ferris wheel–shaped islands (FWIs) capable of effectively suppressing crack propagation at the interface under various deformation modes (stretching, twisting, poking, and crumpling). The optimized FWIs have notable increased strain at failure and fatigue life compared with conventional circle- and square-shaped islands. Stretchable electronics composed of various rigid components (LED and coin cell) were demonstrated using intrinsically stretchable printed electrodes. Furthermore, electronic skin capable of differentiating various tactile stimuli without interference was demonstrated. Our method enables stretchable electronics that can be used under various geometrical forms with notable enhanced durability, enabling stretchable electronics to withstand potentially harsh conditions of everyday usage.

Stretchable conductors for stretchable field-effect transistors and functional circuits

“…165 In addition, the geometrically engineered Ferris wheel-shaped islands (FWIs) provided the elastomer substrate with the capability of restraining crack propagation under various deformation modes. 166 However, the gate dielectrics built in intrinsic s-FETs require not only excellent mechanical flexibility but also high permittivity. 154,167,168 For example, the interfacial polarization of poly(thioether) and polysiloxane is enhanced by the phase separation structure of the triblock copolymer, thereby improving the dielectric constant.…”

“…In addition, stretchable electronics composed of various rigid components were demonstrated using intrinsically stretchable Ag flake/Ecoflex composite electrodes with screen printing. 166 The hybrid solutions containing 82% of AgF were screen-printed on Ecoflex substrate with or without islands via a metal mask. The electrode on the island-free Ecoflex substrate has an initial conductivity of 400 S cm −1 and a high elongation of 295%.…”

“…However, to obtain highly deformable insulators and excellent devices, such as ion insulators with multi-strength hydrogen bonding interactions, the polymer design of insulator materials with large specific capacitance and good chemical durability is necessary. 328 Alternatively, for existing dielectric materials, although the dielectric constant of the organic material is usually low, a small operating voltage can be obtained through thickness control and patterned geometrical shapes in the insulator layers, 166,463 such as FWIs, which can effectively suppress crack propagation at the interface and considerably enhance the durability of stretchable electronics.…”

Reliability of printed stretchable electronics based on nano/micro materials for practical applications

“…Also, the shape optimization of rigid islands can change the distribution of stress and improve the reliability of hybrid electronics. Yang et al proposed one type of rigid island with a Ferris wheel shape which can significantly weaken the propagation of cracks at the rigid–soft junctions upon mechanical deformations, 96 as shown in Fig. 3C.…”

Decoupling Transmission and Transduction for Improved Durability of Highly Stretchable, Soft Strain Sensing: Applications in Human Health Monitoring

“…In order to overcome these limitations, recent research has focused on the development of highly-stretchable, large-deformation strain sensors using novel materials, including but not limited to ionic hydrogels, conductive polymer composites, and liquid-metal-in-rubber [ 1 , 2 , 3 , 4 ]. These methods can produce sensors with impressive signal-to-noise (SNR) ratios, but they often suffer from baseline conductive drift and unreliable interconnects between soft and rigid conductive components that limit their cyclic durability, having stable performance for up to 60,000 cycles at best [ 5 , 6 , 7 , 8 , 9 ]. Longer cycle life has been demonstrated but with evidence of sensor drift and changes in signal amplitude over time [ 10 , 11 ].…”