Elastomers with Microislands as Strain Isolating Substrates for Stretchable Electronics

Abstract Inorganic materials cannot be deposited perfectly on soft elastomers due to wrinkles caused by thermal mismatch in deposition, which limits heterogeneous integration for stretchable inorganic electronics. Herein, a microisland strategy is proposed to isolate the thermal strain mismatch between inorganic materials and soft elastomers, to eliminate undesirable wrinkles. Theoretical model sets up the critical dimensions of microislands to avoid wrinkling. Whether wrinkles appear with different dimensions of the microislands predicted by the theoretical model is consistent with experiments of using copper film on a polydimethylsiloxane (PDMS) substrate. Another advantage of this strategy is to reduce the energy release rate between stiff film and soft substrate in a finite element analysis (FEA) study, which avoids delamination between the film and the substrate. Examples of light emitting diode array optoelectronic devices with microislands are presented to show their advantages with respect to designs without microislands. This strategy is suitable for any situation in which a stiff film is deposited on a soft elastomer substrate, providing a viable process for fabricating stretchable electronics and improving the device yield because there is no transfer printing process.