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New Approach to Simultaneous In Situ Measurements of the Air/Liquid/Solid Interface Using PM-IRRAS

Chathura de Alwis1, Timothy R. Leftwich2, Kathryn A. Perrine1,*

1 – Department of Chemistry, Michigan Technological University, Houghton, MI 49931

2 – Department of Material Science & Engineering, Michigan Technological University, Houghton, MI 49931

*corresponding author; kaperrin@mtu.edu

Abstract

Abstract Image

Vibrational spectroscopy techniques have evolved to measure gases, liquids, and solids at surfaces and interfaces. In the field of surface-sensitive vibrational spectroscopy, infrared spectroscopy measures the adsorption on surfaces and changes from reactions. Previous polarized modulated-infrared reflection–absorption spectroscopy (PM-IRRAS) measurements at the gas/solid interface were developed to observe catalytic reactions near reaction conditions. Other PM-IRRAS measurements use liquid cells where the sample is submerged and compressed against a prism that has traditionally been used for electrochemical reactions. This article presents a new method that is used to observe in situ adsorption of molecules using PM-IRRAS at the gas/liquid/solid interface. We demonstrate the meniscus method by measuring the adsorption of octadecanethiol on gold surfaces. Characterization of self-assembled monolayers (SAMs), the “gold standard” for PM-IRRAS calibration measurements, was measured in ethanol solutions. The condensed-phase (air/liquid) interface in addition to the liquid/solid interface was measured simultaneously in solution. These are compared with liquid attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy measurements to confirm the presence of the SAM and liquid ethanol. A model of the three-phase system is used to approximate the thickness of the liquid ethanol layer and correlate these values to signal attenuation using PM-IRRAS. This proof-of-concept study enables the measurement of reactions at the gas/liquid/solid interface that could be adapted for other reactions at the electrode and electrolyte interfaces with applications in environmental science and heterogeneous catalysis.

Au/Cr coated glass slides produced using the 6″ Sputtering system in the Microfabrication Facility

de Alwis, C., Leftwich, T.R. and Perrine, K.A., 2020. New Approach to Simultaneous In Situ Measurements of the Air/Liquid/Solid Interface Using PM-IRRAS. Langmuir, 36(13), pp.3404-3414.


Magneto-optics of subwavelength all-dielectric gratings

ANDREY A. VORONOV,1,2,* DOLENDRA KARKI,3 DARIA O. IGNATYEVA,1,2 MIKHAIL A. KOZHAEV,2,4 MIGUEL LEVY,3 AND VLADIMIR I. BELOTELOV1,2

1- Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, 1-2, Moscow 119991, Russia
2 – Russian Quantum Center, Bolshoy Boulevard 30, bld. 1, Moscow 121205, Russia
3 – Physics Department, Michigan Technological University, Houghton, MI 49931, USA
4 – Prokhorov General Physics Institute of the Russian Academy of Science, 38 Vavilov Street, Moscow 119991, Russia 

We provide the experimental research on a novel type of all-dielectric magnetic structure designed to achieve an enhanced magneto-optical response. 1D grating fabricated via etching of bismuth substituted iron garnet film supports the excitation of optical guided modes, which are highly sensitive to the external magnetic field. A unique feature of proposed structure is the synergetic combination of high transparency, tunability, high Q-factor of the resonances and superior magneto-optical response that is two orders higher in magnitude than in the non-structured smooth iron-garnet film. The considered all-dielectric magnetic garnet structures have great potential in various fields including the magneto-optical modulation of light, biosensing and magnetometry.

Voronov, A.A., Karki, D., Ignatyeva, D.O., Kozhaev, M.A., Levy, M. and Belotelov, V.I., 2020. Magneto-optics of subwavelength all-dielectric gratings. Optics Express, 28(12), pp.17988-17996.


Fano resonances from plasmon-exciton coupling in hetero-bilayer WSe2-WS2 on Au nanorod arrays

Jinlin Zhang1, Manpreet Boora1, Taylor Kaminski1, Chito Kendrick2, Yoke Khin Yap1, and Jae Yong Suh1*

1 – Department of Physics, Michigan Technological University, MI, 49931, USA

2 – Department of Electrical and Computer Engineering, Michigan Technological University, MI, 49931, USA

*Corresponding author: jsuh@mtu.edu

Plasmon-exciton coupling in hetero-bilayer of WSe2 and WS2 transferred onto Au nanorod arrays is studied. Dark-field scattering measurements reveal that the in-plain dipole moment of excitons in monolayer WS2 allows only the narrow spectral range of 30 nm for the resonant coupling between the localized particle plasmons from Au nanorods and the bright excitons from WS2. We demonstrate that the q-parameter that represents the asymmetry of Fano resonances from plasmon-exciton coupling can be controlled by the polarization states of incident light. Surface lattice resonances in between individual Au nanorods play a role to diminish the damping factor of plasmon-exciton coupling in the arrays

WSe2 and WS2 layer transfer process optimized and completed in Microfabrication Facility

WS2 and WSe2 monolayers for this publication were provided by The Pennsylvania State University Two-Dimensional Crystal Consortium–Materials Innovation Platform (2DCC-MIP) which is supported by NSF co-operative agreement DMR-1539916.

Zhang, Jinlin, Manpreet Boora, Taylor Kaminski, Chito Kendrick, Yoke Khin Yap, and Jae Yong Suh. “Fano resonances from plasmon-exciton coupling in hetero-bilayer WSe2-WS2 on Au nanorod arrays.” Photonics and Nanostructures-Fundamentals and Applications (2020): 100783.


Virus Isoelectric Point Determination Using Single-Particle Chemical Force Microscopy

Xue Mi1, Emily K. Bromley1, Pratik U. Joshi1, Fei Long2, and Caryn L. Heldt1*

1 – Department of Chemical Engineering, Michigan Technological University, USA

2 – Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, USA

*Corresponding author: heldt@mtu.edu

Virus colloidal behavior is governed by the interaction of the viral surface and the surrounding environment. One method to characterize the virus surface charge is the isoelectric point (pI). Traditional determination of virus pI has focused on the bulk characterization of a viral solution. However, virus capsids are extremely heterogeneous, and a single-particle method may give more information on the range of surface charge observed across a population. One method to measure the virus pI is chemical force microscopy (CFM). CFM is a single-particle technique that measures the adhesion force of a functionalized atomic force microscope (AFM) probe and, in this case, a virus covalently bound to a surface. Non-enveloped porcine parvovirus (PPV) and enveloped bovine viral diarrhea virus (BVDV) were used to demonstrate the use of CFM for viral particles with different surface properties. We have validated the CFM to determine the pI of PPV to be 4.8–5.1, which has a known pI value of 5.0 in the literature, and to predict the unknown pI of BVDV to be 4.3–4.5. Bulk measurements, ζ-potential, and aqueous two-phase system (ATPS) cross-partitioning methods were also used to validate the new CFM method for the virus pI. Most methods were in good agreement. CFM can detect the surface charge of viral capsids at a single-particle level and enable the comparison of surface charge between different types of viruses.

Cr/Au coated glass slides produced in the Microfabrication Facility using the Perkin-Elmer 2400 Sputter Tool 6″

Mi, Xue, Emily Bromley, Pratik Umesh Joshi, Fei Long, and Caryn L. Heldt. “Virus isoelectric point determination using single-particle chemical force microscopy.” Langmuir 2020, 36, 1, 370-378


Broadband Bias-Magnet-Free On-Chip Optical Isolators with Integrated Thin Film Polarizers

Dolendra Karki1, Vincent Stenger2, Andrea Pollick2, and Miguel Levy1*

1 – Physics Department, Michigan Technological University, Houghton, MI 49931 USA

2 – R and D, SRICO, Inc., Columbus, Ohio United States

*Corresponding author: mlevy@mtu.edu

Most on-chip optical isolators utilize nonreciprocal magneto-optic (MO) garnet-materials that require an external bias magnetic field to operate. The magnetic field is applied though incorporation of either a permanent magnet or an active electromagnet. Permanent magnets add significantly to device bulk and electromagnets increase fabrication complexity and power consumption. Hence, it is highly desirable to reduce or eliminate the magnetizing component in these devices. Here, we experimentally demonstrate a first of its kind bias-magnet-free (BMF) on-chip waveguide optical isolator with integrated Polarcor™ UltraThin™ polarizers. The BMF isolator device obviates the need for magnetizing components while possessing superior performance, relative to other on-chip isolators, with ≥ 25 dB of isolation ratio (IR), and le 3.5 dB of insertion loss (IL) across the entire infrared optical C-band.

Sample dicing done in the Microfabrication Facility

Karki, Dolendra, Vincent Stenger, Andrea Pollick, and Miguel Levy. “Broadband Bias-Magnet-Free On-Chip Optical Isolators With Integrated Thin Film Polarizers.” Journal of Lightwave Technology 38, no. 4 (2019): 827-833.


Award Winning Adhesives Researcher Credits Microfabrication Facility

The Bhakta Rath Research Award honors a graduate student and faculty mentor for in-depth work with social impact. The 2019 winners are two biomedical engineers with a sticky past.

A smart adhesive doesn’t adhere all the time. In 2015, when Ameya Narkar started his doctoral research with Bruce Lee, associate professor of biomedical engineering at Michigan Technological University, the two turned to biological sources for a glue that could be turned on and off.

Q: How have your methods helped make the project successful?

Ameya Narkar: Our biomedical engineering department is full of approachable experts. It’s a small team and an effective one. I could walk down to a faculty member’s office and ask for advice when our project branched into areas beyond our lab’s expertise. Plus, I was able to work closely with the people in the Applied Chemical and Morphological Analysis Laboratory and the microfabrication facility. Collaboration is essential to successful research.

Read more at Michigan Tech News, by Allison Mills.


Firstnano chemical vapor deposition system

A firstnano chemical vapor deposition (CVD) system has been installed in the Michigan Technological University Microfabrication Shared facility (MFF). This system allows for the growth of carbon nanotubes (CNTs) using hydrogen and ethylene and an iron catalyst. This capability was brought into the MFF by Dr. Parisa Abadi through her start up package and has generously allowed other faculty and researchers at MTU access to this system. If you would like to use the system, or would like like more information please contact Dr. Parisa Abadi (pabadi at mtu dot edu) or Chito Kendrick (cekendri@mtu.edu).

 

 

 

 

 

 

 

First CNT growth using the nanofirst system – Images taken using the FE-4700 SEM in ACMAL


MFF Internal Use Fee Rates

Dear Users,
The Microfab just went through it’s biyearly review of use rates. This has lead to changes to all three rates:
  • D98077 (baseline) – $19.50 ($1.00 decrease)
  • D98081 (EV620 Mask aligner) – $71 ($0.50 increase)
  • D98095 (thin film deposition and etching) – $43 ($0.50 increase)
I am doing my best to keep these rates as low as possible to allow for more usage at the lowest cost possible.

Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices

Many biological lab-on-a-chip applications require electrical and optical manipulation as well as detection of cells and biomolecules. This provides an intriguing challenge to design robust microdevices that resist adverse electrochemical side reactions yet achieve optical transparency. Physical isolation of biological samples from microelectrodes can prevent contamination, electrode fouling, and electrochemical byproducts; thus this manuscript explores hafnium oxide (HfO2) films – originating from traditional transistor applications – for suitability in electrokinetic microfluidic devices for biological applications. HfO2 films with deposition times of 6.5, 13, and 20 min were sputter deposited onto silicon and glass substrates. The structural, optical, and electrical properties of the HfO2 films were investigated using atomic force microscopy (AFM), X-ray diffractionenergy dispersive X-ray spectroscopyFourier transform infrared spectroscopy, ellipsometry, and capacitance voltage. Electric potential simulations of the HfO2 films and a biocompatibility study provided additional insights. Film grain size after corrosive Piranha treatment was observed via AFM. The crystalline structure investigated via X-ray diffraction revealed all films exhibited the (111) characteristic peak with thicker films exhibiting multiple peaks indicative of anisotropic structures. Energy dispersive X-ray spectroscopy via field emission scanning electron microscopy and Fourier transform infrared spectroscopy both corroborated the atomic ratio of the films as HfO2. Ellipsometry data from Si yielded thicknesses of 58, 127, and 239 nm and confirmed refractive index and extinction coefficients within the normal range for HfO2; glass data yielded unreliable thickness verifications due to film and substrate transparency. Capacitance-voltage results produced an average dielectric constant of 20.32, and the simulations showed that HfO2 dielectric characteristics were sufficient to electrically passivate planar microelectrodes. HfO2 biocompatibility was determined with human red blood cells by quantifying the hemolytic potential of the HfO2 films. Overall results support hafnium oxide as a viable passivation material for biological lab-on-a-chip applications.

Collins, J.L., Hernandez, H.M., Habibi, S., Kendrick, C.E., Wang, Z., Bihari, N., Bergstrom, P.L. and Minerick, A.R., 2018. Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices. Thin Solid Films662, pp.60-69.