High Performance, Biocompatible Dielectric Thin‐Film Optical Filters Integrated with Flexible Substrates and Microscale Optoelectronic Devices

Abstract

Miniaturized, wearable, and implantable optoelectronic devices and systems provide incomparable opportunities for applications in biomedical fields. Optical filters with wavelength selective reflective/transmissive responses that can be integrated onto these biointegrated platforms are critically important for high performance operation. Here, high quality, dielectric thin‐film optical filters on unconventional substrates via transfer printing are reported. Designed filters formed on flexible substrates exhibit highly spectral selective transmission and reflection, with the maximum optical density at stop band reaching 6. Additionally, freestanding filter membranes are combined with microscale optoelectronic devices, achieving enhanced emission intensity for light‐emitting diodes and spectral sensitivity for photovoltaic detectors. Finally, their in vitro cytotoxicity is evaluated within cell culture, and in vivo biocompatibility is supported in living animals. The presented results offer viable routes to high performance optical components for advanced biointegrated optoelectronic systems.

Colocalized, Bidirectional Optogenetic Modulations in Freely Behaving Mice with a Wireless Dual-Color Optoelectronic Probe

“…All the devices (red LEDs, blue LEDs and filters) are formed in thin-film, microscale formats (lateral dimension ~ 125 m × 180 µm, thickness ~ 5-7 µm) through epitaxial liftoff, and vertically assembled via transfer printing [34][35][36] (Figure 1d). The intrinsic optical transparency of active layers in the InGaN blue micro-LED allows emissions from the red micro-LED passing through with minimal losses.…”

“…Steady-state temperature rises are recorded from the thermocouple with a thermometer (Physitemp,.Thermal modeling3D steady-state heat transfer models are established by finite element analysis (Comsol Multiphysics). The parameters of the brain use in the model include: density 1.1 g/cm3 , thermal conductivity 0.5 W/m/K, heat capacity 3650 J/kg/K, and the natural heat convection to air. The micro-LED probe serves as the heat source, with the input thermal power estimated by P = V × I × (1 − EQE), where V, I and EQE are the measured voltage, current, and corresponding external quantum efficiencies for LEDs.Wireless Circuit DesignA customized circuit module is designed to wirelessly operate the implantable micro-LED probe by independently controlling the red and the blue micro-LEDs for bi-directional modulation.…”

Fabrication and Analysis of Polydimethylsiloxane (PDMS) Microchannels for Biomedical Application

“…Therefore, the PDMS has been used to fabricate the microchannels for varicose vein implantation. This polymer is naturally flexible, biocompatible and exhibits less friction with the flow speed [16,44,45]. These polymer channels can be implanted to avoid tissue-damaging effect after the removal of varicose veins.…”

“…In this study, blood (plasma) density is considered 1025 kg/m 3 and blood (cells) density is taken as 1125 kgm −3 [44,57]. Typically, the blood density for humans (female and male) is taken as 1060 kgm −3 [16,45]. Some possible PDMS-based implants in humans depending on the requirement have been shown in Figure 2.…”

“…The core purpose of the present work is to engineer and evaluate the use of PDMS microchannels as a potential replacement for varicose veins. These bioengineered veins must promote a better blood flow and avoid tissue-damaging [16].…”