Elastomer thin-film pressure sensor based on embedded photonic tunnel-junction arrays

We propose an elastomer thin-film pressure sensor enabled by pressure-sensitive optical signals through vertical photonic tunnel-junction couplers. We provide the operation principle, design, fabrication, and test results from a 50 μm thick polydimethylsiloxane sheet accommodating embedded vertical photonic tunnel-junction couplers. The result with a 5 mm long device shows a differential optical power change that is ∼140% of the incident power under moderate external pressure of ∼40 kPa, thereby clearly demonstrating a robust pressure-sensing capability realized in a highly flexible, lightweight, transferrable, optically transparent, and bio-compatible thin-film material. Therefore, the proposed approach potentially enables versatile pressure and touch sensors for many applications in practice.