Siloxane Hybrid Material-Encapsulated Highly Robust Flexible μLEDs for Biocompatible Lighting Applications

Abstract

Flexible micro-light-emitting diodes (f-μLEDs) have been regarded as an attractive light source for the next-generation human–machine interfaces, thanks to their noticeable optoelectronic performances. However, when it comes to their practical utilizations fulfilling industrial standards, there have been unsolved reliability and durability issues of the f-μLEDs, despite previous developments in the high-performance f-μLEDs for various applications. Herein, highly robust flexible μLEDs (f-HμLEDs) with 20 × 20 arrays, which are realized by a siloxane-based organic–inorganic hybrid material (SHM), are reported. The f-HμLEDs are created by combining the f-μLED fabrication process with SHM synthesis procedures (i.e., sol–gel reaction and successive photocuring). The outstanding mechanical, thermal, and environmental stabilities of our f-HμLEDs are confirmed by a host of experimental and theoretical examinations, including a bending fatigue test (105 bending/unbending cycles), a lifetime accelerated stress test (85 °C and 85% relative humidity), and finite element method simulations. Eventually, to demonstrate the potential of our f-HμLEDs for practical applications of flexible displays and/or biomedical devices, their white light emission due to quantum dot-based color conversion of blue light emitted by GaN-based f-HμLEDs is demonstrated, and the biocompatibility of our f-HμLEDs is confirmed via cytotoxicity and cell proliferation tests with muscle, bone, and neuron cell lines. As far as we can tell, this work is the first demonstration of the flexible μLED encapsulation platform based on the SHM, which proved its mechanical, thermal, and environmental stabilities and biocompatibility, enabling us to envisage biomedical and/or flexible display applications using our f-HμLEDs.

Metal–Organic Framework-Derived Carbon as a Photoacoustic Modulator of Alzheimer’s β-Amyloid Aggregate Structure

“…For proceeding the LIVE/DEAD assay, N2a cells were subcultured in a cell culture dish (growth area: 9.24 cm 2 ) at a density of 200,000 cells per well and incubated for 24 h. Then 500 μL of MOFC solution with a concentration of 0.250 mg mL –1 was injected into the cell culture dish. N2a cells were further incubated for 7 days in the growth medium containing MOFC nanoparticles and stained by LIVE/DEAD assay kit consisting of calcein AM and ethidium homodimer-1 as referred to in the literature. , The LIVE/DEAD assay results were obtained by a fluorescence microscope (Eclipse 80i, Nikon Inc., Japan). MTS assay is a colorimetric method that determines live cells by measuring the absorbance of 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H -tetrazolium reagent.…”

“…N2a cells were further incubated for 7 days in the growth medium containing MOFC nanoparticles and stained by LIVE/DEAD assay kit consisting of calcein AM and ethidium homodimer-1 as referred to in the literature. 65,66 The LIVE/DEAD assay results were obtained by a fluorescence microscope (Eclipse 80i, Nikon Inc., Japan). MTS assay is a colorimetric method that determines live cells by measuring the absorbance of 3-(4,5dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium reagent.…”

Linnaeite Mineral for NIR Light-Triggered Disruption of Alzheimer’s Pore-Forming Aβ Oligomers

“…For LIVE/DEAD staining assay, N2a cells were spread at a density of 5000 cells dish –1 in a confocal dish (diameter: 20 mm), and 100 μL of linnaeite nanoparticle solution (0.025 mg mL –1 in DMEM) was injected to the cell culture dish after 24 h of incubation. A LIVE/DEAD staining assay was performed at day 1 and 3 after the nanoparticle injection, as done in a previous study , For the alamarBlue assay, N2a cells were spread at a density of 5,000 cells well –1 in a 96-well plate, and incubated with different concentrations of linnaeite nanoparticles (0 to 500 μg mL –1 ) for a day after allowing the cell adhesion for 24 h. To confirm the alleviation effect of linnaeite nanoparticles on βPFOs, we incubated N2a cells in a 96-well plate for 48 h with a low-serum medium (DMEM containing 0.1% FBS and 1% AA) following the literature with modifications. Afterward, the N2a cells were treated by 1.5 uL of βPFO solution (90 μM) for 72 h, and the cell viability was assessed by an alamarBlue assay through a microplate reader (Victor 3, PerkinElmer Inc., USA) that equipped with optimal excitation and emission filters (λ ex = 560 nm, λ ex = 590 nm).…”

Direct Optical Patterning of Quantum Dots: One Strategy, Different Chemical Processes

“…The chemistry of the Si-O-Si bond was already illustrated in Section 3.1 ( Figure 8 ), and here will be described the capacity of siloxanes to act as a collective encapsulating agent with high chemical thermal and mechanical stability, as recently presented by Bae’s group for the stabilization of scQDs in different conditions [ 83 , 84 , 85 , 86 , 87 ].…”