More Like this

1. Flexible and Transparent Metal Nanowire Microelectrode Arrays and Interconnects for Electrophysiology, Optogenetics, and Optical Mapping

   https://doi.org/10.1002/admt.202100225  

   Chen, Zhiyuan; Boyajian, Nicolas; Lin, Zexu; Yin, Rose T.; Obaid, Sofian N.; Tian, Jinbi; Brennan, Jaclyn A.; Chen, Sheena W.; Miniovich, Alana N.; Lin, Leqi; et al (June 2021, Advanced Materials Technologies)

   Abstract Transparent microelectrodes have recently emerged as a promising approach for crosstalk‐free multifunctional electrical and optical biointerfacing. High‐performance flexible platforms that allow seamless integration with soft tissue systems for such applications are urgently needed. Here, silver nanowires (Ag NWs)‐based transparent microelectrode arrays (MEAs) and interconnects are designed to meet this demand. The nanowire networks exhibit a high optical transparency >90.0% at 550 nm, and superior mechanical stability up to 100,000 bending cycles at 5 mm radius. The Ag NWs microelectrodes preserve low normalized electrochemical impedance of 3.4–15 Ω cm²at 1 kHz, and the interconnects demonstrate excellent sheet resistance (R_sh) of 4.1–25 Ω sq⁻¹. In vivo histological analysis reveals that the Ag NWs structures are biocompatible. Studies on Langendorff‐perfused mouse and rat hearts demonstrate that the Ag NWs MEAs enable high‐fidelity real‐time monitoring of heart rhythm during co‐localized optogenetic pacing and optical mapping. This proof‐of‐concept work illustrates that the solution‐processed, transparent, and flexible Ag NWs structures are a promising candidate for the next‐generation of large‐area multifunctional biointerfaces for interrogating complex biological systems in basic and translational research. 

   more » « less
2. Effect of Thickness of a Dye-doped Polymeric Film on the Concentration Quenching of Luminescence

   Sangeeta Rout, S. Koutsares (January 2021, CLEO Conference (virtual), May 9 – May 14, 2021, paper JW1A.96.)

   null (Ed.)

   We have studied the dependence of concentration quenching of luminescence on the thickness d of dye-doped polymeric films (HITC:PMMA) and found a strong inhibition of the donor-acceptor energy transfer (concentration quenching) at small values of d. 

   more » « less
3. Synthesis and optoelectronic properties of ultrathin Ga ₂ O ₃ nanowires

   https://doi.org/10.1039/D0TC02040K  

   Sutter, Eli; Idrobo, Juan Carlos; Sutter, Peter (August 2020, Journal of Materials Chemistry C)

   null (Ed.)

   Gallium oxide (Ga 2 O 3 ) and its most stable modification, monoclinic β-Ga 2 O 3 , is emerging as a primary material for power electronic devices, gas sensors and optical devices due to a high breakdown voltage, large bandgap, and optical transparency combined with electrical conductivity. Growth of β-Ga 2 O 3 is challenging and most methods require very high temperatures. Nanowires of β-Ga 2 O 3 have been investigated extensively as they might be advantageous for devices such as nanowire field effect transistors, and gas sensors benefiting from a large surface to volume ratio, among others. Here, we report a synthesis approach using a sulfide precursor (Ga 2 S 3 ), which requires relatively low substrate temperatures and short growth times to produce high-quality single crystalline β-Ga 2 O 3 nanowires in high yields. Even though Au- or Ag-rich nanoparticles are invariably observed at the nanowire tips, they merely serve as nucleation seeds while the nanowire growth proceeds via supply and local oxidation of gallium at the substrate interface. Absorption and cathodoluminescence spectroscopy on individual nanowires confirms a wide bandgap of 4.63 eV and strong luminescence with a maximum ∼2.7 eV. Determining the growth process, morphology, composition and optoelectronic properties on the single nanowire level is key to further application of the β-Ga 2 O 3 nanowires in electronic devices. 

   more » « less
4. Effect of Random Nanostructured Metallic Environments on Spontaneous Emission of HITC Dye

   https://doi.org/10.3390/nano10112135  

   Rout, Sangeeta; Qi, Zhen; Petrosyan, Ludvig S.; Shahbazyan, Tigran V.; Biener, Monika M.; Bonner, Carl E.; Noginov, Mikhail A. (November 2020, Nanomaterials)

   null (Ed.)

   We have studied emission kinetics of HITC laser dye on top of glass, smooth Au films, and randomly structured porous Au nanofoams. The observed concentration quenching of luminescence of highly concentrated dye on top of glass (energy transfer to acceptors) and the inhibition of the concentration quenching in vicinity of smooth Au films were in accord with our recent findings. Intriguingly, the emission kinetics recorded in different local spots of the Au nanofoam samples had a spread of the decay rates, which was large at low dye concentrations and became narrower with increase of the dye concentration. We infer that in different subvolumes of Au nanofoams, HITC molecules are coupled to the nanofoams weaker or stronger. The inhibition of the concentration quenching in Au nanofoams was stronger than on top of smooth Au films. This was true for all weakly and strongly coupled subvolumes contributing to the spread of the emission kinetics. The experimental observations were explained using theoretical model accounting for change in the Förster radius caused by the strong energy transfer to metal. 

   more » « less
5. CdSe/Ag Hybrid Aerogels: Integration of Plasmonic and Excitonic Properties of Metal–Semiconductor Nanostructures via Sol–Gel Assembly

   https://doi.org/10.1002/adpr.202100084  

   Liyanage, Dilhara; Spera, Drew Z.; Sarkar, Rajib; Troesch, Brendan P.; Arachchige, Indika U. (July 2021, Advanced Photonics Research)

   Metal–semiconductor hybrid nanomaterials (HNMs) exhibit unique properties that are distinct from individual nanostructures, leading to promising applications in optical technologies. The interfacial linkage of semiconductor and metal nanoparticles (NPs) via cogelation is an effective strategy to produce HNMs that show strong plasmon‐exciton coupling and improved physical properties. However, optical properties of these hybrids show little to no tunability. Herein, CdSe/Ag hybrid aerogels that show tunable absorption and photoluminescence (PL) are produced by cogelation of CdSe nanorods (NRs) or NPs with Ag hollow NPs. Hybrid electronic states are created by overlapping the excitonic absorption of CdSe NRs or NPs with the plasmonic absorption of Ag NPs. Physical characterization of the hybrids reveals an interconnected network of hexagonal CdSe and cubic Ag NPs, linked by Ag⁺and Se²⁻surface species, without intervening ligands. PL spectra exhibit maxima at 640 and 720 nm for the CdSe NPs/Ag and CdSe NRs/Ag hybrids, respectively, corresponding to new radiative decay mechanisms. Time‐resolved PL data support the emergence of new radiative pathways, kinetically and energetically distinct from the excitonic and plasmonic properties of primary NPs. This new approach of metal–semiconductor hybrid formation through cogelation is intriguing for the design of high‐efficiency HNMs without detrimental PL quenching. 

   more » « less