Rubbery Electronics Fully Made of Stretchable Elastomeric Electronic Materials

Abstract

processes, and device structures have been transforming traditional wafer electronics to be soft, stretchy, and reconfigurable. In particular, owing to their superior mechanical characteristics, i.e., soft, bendable, stretchable, and twistable, stretchable electronics hold promise in health monitors, [1] medical implants, [2][3][4][5][6][7][8][9][10] artificial skins, [5,6,[11][12][13][14][15] human-machine interfaces, [11,[16][17][18][19][20] wearable internet of things, [21][22][23][24] etc.As the core and fundamental building block of active electronics, transistors constructed from semiconductors, conductors, and dielectrics are key to enabling electrical functionalities such as switching and amplification. To make transistors stretchable, either the associated electronic materials need to be stretchable or special mechanical structures and layouts need to be included in the transistor design. There are many studies reporting stretchable conductors, as reviewed in the following, while many readily available dielectric materials are stretchy. These have significantly offered many possible options in the device design space. To date, the dominant semiconductors employed for stretchable electronics are either conventional or emerging semiconductors. However, these materials, either in the format of inorganics (such as Si, GaAs, oxides) or organics (such as poly(3-hexylthiophene-2,5-diyl) or P3HT, pentacene), are mechanically nonstretchable. [20,21] Existing strategies to make these nonstretchable semiconductors stretchable mainly involve creating special mechanical structures or architectures with these materials, such as out-of-plane wrinkles, [25,26] in-plane serpentines, [27,28] rigid islands with deformable interconnects, [29][30][31] and kirigami architectures, [32][33][34] to eliminate mechanical strain while they are stretched. However, these approaches require sophisticated structural designs, complicated manufacturing processes, or consume a large area due to stretchable interconnection, all of which pose substantial challenges in high-density integration, packaging, associated high cost, and mass production.Constructing devices all from intrinsically stretchable elastomeric electronic materials offers another interesting yet promising route toward stretchable transistors and electronics. These types of electronics, namely rubbery electronics, neatly avoid the aforementioned challenges since they do not require structural engineering for device fabrication and the manufacturing processes can be adopted into conventional fabrication processes. [29,35] In addition, rubbery electronics offer better cost Stretchable electronics outperform existing rigid and bulky electronics and benefit a wide range of species, including humans, machines, and robots, whose activities are associated with large mechanical deformation and strain. Due to the nonstretchable nature of most electronic materials, in particular semiconductors, stretchable electronics are mostly realized through the strategies of architectural engine...

Soft Electronics for the Skin: From Health Monitors to Human–Machine Interfaces

“…Two strategies have been applied to achieve mechanical stretchability in soft electronics: 1) utilizing intrinsically stretchable, rubbery materials including rubbery electronic materials (semiconductors, conductors, and dielectrics) [14,15,24,[35][36][37][38][39][40][41][42][43][44][45] and liquid metals [46][47][48][49] to build the electronics; 2) employing engineered structures like wrinkles, [34,[50][51][52][53][54][55][56] serpentines, [12,17,33,44,[57][58][59][60][61] island-bridge structures, [62,63] textiles, [64] origami, [65,66] kirigami, [37,67] and microcracks [68] to accommodate the induced strain. [30,[69][70][71][7...…”

Ink‐Based Additive Nanomanufacturing of Functional Materials for Human‐Integrated Smart Wearables

“…solution-processed nanomaterials into designer complex shapes in a spatially controlled manner. [107][108][109][110][111] Ink-based AM techniques, such as inkjet printing and aerosol jet printing, along with spray coating, are feasible for printing ink materials of a low viscosity. [77,112,113] These printing methods split functional ink into microdroplets and deposit the droplets onto substrates.…”

Advances in Materials for Soft Stretchable Conductors and Their Behavior under Mechanical Deformation

“…Although the elastomeric material often acts as a non-conductive polymer support layer that interfaces with a separate active material layer, conductive fillers (e.g., nanoparticles, carbon nanotubes) can also be dispersed within the polymer matrix to create composite stretchable sensors [ 42 , 43 , 44 ]. Composite sensors, however, are often not as conductive as their bulk materials counterparts, and filler content can change the mechanical properties of the elastomer.…”