All Publications

  • Combinatorial Polyacrylamide Hydrogels for Preventing Biofouling on Implantable Biosensors. Advanced materials (Deerfield Beach, Fla.) Chan, D., Chien, J., Axpe, E., Blankemeier, L., Baker, S. W., Swaminathan, S., Piunova, V. A., Zubarev, D. Y., Maikawa, C. L., Grosskopf, A. K., Mann, J. L., Soh, H. T., Appel, E. A. 2022: e2109764


    Biofouling on the surface of implanted medical devices and biosensors severely hinders device functionality and drastically shortens device lifetime. Poly(ethylene glycol) and zwitterionic polymers are currently considered "gold standard" device coatings to reduce biofouling. To discover novel anti-biofouling materials, we created a combinatorial library of polyacrylamide-based copolymer hydrogels and screened their ability to prevent fouling from serum and platelet-rich plasma in a high-throughput parallel assay. We found certain non-intuitive copolymer compositions exhibit superior anti-biofoulingproperties over current gold standard materials, and employed machine learning to identify key molecular features underpinning their performance. For validation, we coated the surfaces of electrochemical biosensors with our hydrogels and evaluated their anti-biofouling performance in vitro and in vivo in rodent models. Our copolymer hydrogels preserved device function and enabled continuous measurements of a small-molecule drug in vivo better than gold standard coatings. The novel methodology we describe enables the discovery of anti-biofouling materials that can extend the lifetime of real-time in vivo sensing devices. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202109764

    View details for PubMedID 35390209

  • Integrated photonics for low transverse emittance, ultrafast negative electron affinity GaAs photoemitters JOURNAL OF APPLIED PHYSICS Blankemeier, L., Rezaeifar, F., Garg, A., Kapadia, R. 2019; 126 (3)

    View details for DOI 10.1063/1.5093938

    View details for Web of Science ID 000476587700013

  • Confined Liquid-Phase Growth of Crystalline Compound Semiconductors on Any Substrate ACS NANO Sarkar, D., Wang, W., Mecklenburg, M., Clough, A. J., Yeung, M., Ren, C., Lin, Q., Blankemeier, L., Niu, S., Zhao, H., Shi, H., Wang, H., Cronin, S. B., Ravichandran, J., Luhar, M., Kapadia, R. 2018; 12 (6): 5158-5167


    The growth of crystalline compound semiconductors on amorphous and non-epitaxial substrates is a fundamental challenge for state-of-the-art thin-film epitaxial growth techniques. Direct growth of materials on technologically relevant amorphous surfaces, such as nitrides or oxides results in nanocrystalline thin films or nanowire-type structures, preventing growth and integration of high-performance devices and circuits on these surfaces. Here, we show crystalline compound semiconductors grown directly on technologically relevant amorphous and non-epitaxial substrates in geometries compatible with standard microfabrication technology. Furthermore, by removing the traditional epitaxial constraint, we demonstrate an atomically sharp lateral heterojunction between indium phosphide and tin phosphide, two materials with vastly different crystal structures, a structure that cannot be grown with standard vapor-phase growth approaches. Critically, this approach enables the growth and manufacturing of crystalline materials without requiring a nearly lattice-matched substrate, potentially impacting a wide range of fields, including electronics, photonics, and energy devices.

    View details for DOI 10.1021/acsnano.8b01819

    View details for Web of Science ID 000436910200010

    View details for PubMedID 29775282

  • Independent tuning of work function and field enhancement factor in hybrid lanthanum hexaboride-graphene-silicon field emitters JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B Rezaeifar, F., Lin, Q., Chen, X., Mattox, T. M., Garg, A., Clough, A., Poudel, N., Blankemeier, L., Sarkar, D., Cronin, S. B., Kapadia, R. 2017; 35 (6)

    View details for DOI 10.1116/1.5001324

    View details for Web of Science ID 000416602700058

  • Scalable Indium Phosphide Thin-Film Nanophotonics Platform for Photovoltaic and Photoelectrochemical Devices ACS NANO Lin, Q., Sarkar, D., Lin, Y., Yeung, M., Blankemeier, L., Hazra, J., Wang, W., Niu, S., Ravichandran, J., Fan, Z., Kapadia, R. 2017; 11 (5): 5113-5119


    Recent developments in nanophotonics have provided a clear roadmap for improving the efficiency of photonic devices through control over absorption and emission of devices. These advances could prove transformative for a wide variety of devices, such as photovoltaics, photoelectrochemical devices, photodetectors, and light-emitting diodes. However, it is often challenging to physically create the nanophotonic designs required to engineer the optical properties of devices. Here, we present a platform based on crystalline indium phosphide that enables thin-film nanophotonic structures with physical morphologies that are impossible to achieve through conventional state-of-the-art material growth techniques. Here, nanostructured InP thin films have been demonstrated on non-epitaxial alumina inverted nanocone (i-cone) substrates via a low-cost and scalable thin-film vapor-liquid-solid growth technique. In this process, indium films are first evaporated onto the i-cone structures in the desired morphology, followed by a high-temperature step that causes a phase transformation of the indium into indium phosphide, preserving the original morphology of the deposited indium. Through this approach, a wide variety of nanostructured film morphologies are accessible using only control over evaporation process variables. Critically, the as-grown nanotextured InP thin films demonstrate excellent optoelectronic properties, suggesting this platform is promising for future high-performance nanophotonic devices.

    View details for DOI 10.1021/acsnano.7b02124

    View details for Web of Science ID 000402498400082

    View details for PubMedID 28463486

  • Bandgap Control via Structural and Chemical Tuning of Transition Metal Perovskite Chalcogenides ADVANCED MATERIALS Niu, S., Huyan, H., Liu, Y., Yeung, M., Ye, K., Blankemeier, L., Orvis, T., Sarkar, D., Singh, D. J., Kapadia, R., Ravichandran, J. 2017; 29 (9)


    Transition metal perovskite chalcogenides are a new class of versatile semiconductors with high absorption coefficient and luminescence efficiency. Polycrystalline materials synthesized by an iodine-catalyzed solid-state reaction show distinctive optical colors and tunable bandgaps across the visible range in photoluminescence, with one of the materials' external efficiency approaching the level of single-crystal InP and CdSe.

    View details for DOI 10.1002/adma.201604733

    View details for Web of Science ID 000396149800011

    View details for PubMedID 28004864