Browsing by Author "Volkmann, Ulrich Georg"
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- ItemAFM Study of Elastic Module of Physical-Vapor-Deposited Phospholipid Membranes(2018) Volkmann, Ulrich Georg; Catalán López, Rodrigo Esteban; Retamal Ponce, María José; Cisternas Fruns, Marcelo Andrés; Moraga Vent, Nicolás Andrés; Díaz Díaz, Diego Ignacio; Corrales, Tomás P.; Pérez-Acle, Tomás; Soto Arriaza, Marco Antonio; Huber, PatrickThe physical study of artificial phospholipid membranes on solid substrates has become a relevant way to gain insights into the physical behavior of cell membranes. The study of mechanical properties of artificial membranes (lab-made) has become possible with the use of atomic force microscopy. Here, we analyze the Young's modulus and adhesion force of several phospholipidic membranes as a function of temperature using Scanning Force Spectroscopy (SFS). Phospholipids were deposited onto double-polished silicon substrates by physical vapor deposition (PVD), as we have recently reported [1, 2]. We have used Raman spectroscopy to show that the chemical structure of our deposited phospholipid remains unaltered after PVD. After PVD we performed AFM and SFS measurements on the following phospholipids: DPPC, DMPC and DSPC. Measurements using AFM in liquid confirm the self-assembly of the phospholipid bilayer. By using SFS of the deposited membrane in liquid, we observe 2 phase transitions, both in Younǵs Modulus, as well as adhesion channels. The measured phase transitions are consistent with the ripple-gel transition and the gel-liquid crystalline phases. Furthermore, we have studied the frequency dependence of these phase transitions by changing the tip velocity in SFS experiments. Supported by FONDECYT grant # 1141105 (UGV), FONDECYT INICIACION grant # 11160664 (TPC), CONICYT Fellowships (RC and MC), Postdoctoral Fellowship FONDECYT 3160803 (MJR) and CONICYT-PIA ACT 1409. [1] María J. Retamal, Marcelo A. Cisternas, Sebastian E. Gutierrez-Maldonado, Tomas Perez-Acle, Birger Seifert, Mark Busch, Patrick Huber and Ulrich G. Volkmann, J. Chem. Phys. 141, 104201 (2014). [2] María Jose Retamal, Tomas P. Corrales, Marcelo A. Cisternas, Nicolas H. Moraga, Diego I. Diaz, Rodrigo E. Catalan, Birger Seifert, Patrick Huber, and Ulrich G. Volkmann. Biomacromolecules 17 (3), 1142 (2016).
- ItemWrinkled TiNAgNW Nanocomposites for High-Performance Flexible Electrodes on TEMPO-Oxidized Nanocellulose(2024) Gence Loik, Herve Patrick; Quero, Franck; Escalona Álvarez, Miguel Benito; Wheatley, Robert; Seifert, Birger; Díaz Droguett, Donovan Enrique; Retamal, María José; Wallentowitz, Sascha; Volkmann, Ulrich Georg; Bhuyan, HemanFlexible electrodes are essential for the development of future wearable such as implantable medicaldevices. While silver nanowire (AgNW) networks are promising candidates for transparent conductive electrodes (TCEs), they suffer from issues such as high roughness, low adhesion, and atmospheric corrosion sensitivity. Many flexible electrodes are made of a wrinkled conductive layer on top of a compliant s ubstrates. Wrinkles provide a way to maintain the integrity and conductivity of the electrode while it is being stretched or bent. In this study, we report on the characterization ofFE-SEMi-transparent electrodes produced by a novel plasma-enhanced pulsed laser deposition (PE-PLD) technique compatible with cellulose nanopaper (CNP) substrates. We combined AgNW with titanium nitride (TiN) layers to form wrinkled conducting nano-composite coatings with excellent electro-mechanical properties. Our results show that the incorporation of AgNW into TiN coatings improves the electrode’s electro-mechanical robustness. Additionally, our data show that CNP/TiNAgNW electrodesexhibit improved stability in air compared to bare AgNW coatings with improved adhesion. These findings have important implications for the development of bio-compatible flexible electronics and could pave the way for the creation of new wearable and implantable medical devices.