Epidermal Inorganic Optoelectronics for Blood Oxygen Measurement

Abstract

Flexible and stretchable optoelectronics, built-in inorganic semiconductor materials, offer a wide range of unprecedented opportunities and will redefine the conventional rigid optoelectronics in biological application and medical measurement. However, a significant bottleneck lies in the brittleness nature of rigid semiconductor materials and the performance's extreme sensitivity to the light intensity variation due to human skin deformation while measuring physical parameters. In this study, the authors demonstrate a systematic strategy to design an epidermal inorganic optoelectronic device by using specific strain-isolation design, nanodiamond thinning, and hybrid transfer printing. The authors propose all-in-one suspension structure to achieve the stretchability and conformability for surrounding environment, and they propose a two-step transfer printing method for hybrid integrating III-V group emitting elements, Si-based photodetector, and interconnects. Owing to the excellent flexibility and stretchability, such device is totally conformal to skin and keeps the constant light transmission between emitting element and photodetector as well as the signal stability due to skin deformation. This method opens a route for traditional inorganic optoelectronics to achieve flexibility and stretchability and improve the performance of optoelectronics for biomedical application.

Experimental and Theoretical Studies of Serpentine Interconnects on Ultrathin Elastomers for Stretchable Electronics

“…Integrations of high‐performance inorganic semiconductors with soft elastomeric substrates establish the foundations for classes of electronic devices that can stretch, twist, and bend, enabling applications in wearable electronics, optogenetics, artificial skins, and many other areas. Stretchability in these systems can be achieved via an “island‐bridge” layout in which conductive traces (bridges) interconnect the rigid, functional components (islands) .…”

Wearable and Implantable Devices for Cardiovascular Healthcare: from Monitoring to Therapy Based on Flexible and Stretchable Electronics

“…It consists of a photodetector (PD) and two quickly alternating light‐emitting diodes (LEDs) with differing wavelengths such as IR (940 nm) + red (660 nm) or green (530 nm) + red. Depending on the application, the PD and LEDs are placed vertically, as in the transmission mode ( Figure a), or horizontally, as in reflection mode. Figure b illustrates the transmitted light pathway of upward incident light to the PD .…”

Flexible inorganic bioelectronics

“…Especially in the biomedical field, electronic devices have to be flexible and/or stretchable in order to intimately integrate with the soft, deformable, and configuration-complicated biological tissue. [25][26][27][28][29][30] Flexibility of the electronic devices can be realized by reducing their thickness, since the bending stiffness decreases at a three orders faster speed with decreasing thickness, while stretchability can be achieved by pre-strain formed wavy configuration, island-bridge structure and serpentine and fractal interconnects design. 23,[31][32][33][34][35][36][37] The main idea in these strategies is to utilize the buckling/post buckling of the delicate patterned inorganic materials to minimize the strain in the functional layer while the whole devices are under large deformation.…”