2228 Microsc. Microanal. 26 (Suppl 2), 2020
doi:10.1017/S1431927620020875 © Microscopy Society of America 2020
Graphene Membrane Encapsulation Platform for Multi-technique
Spectromicroscopy of Wet Objects
Christopher Arble
1
, Hongxuan Guo
2
, Alessia Matruglio
3,4
, Lisa Vaccari
4
and Andrei Kolmakov
1
1
Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg,
Maryland, United States,
2
SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of
Education Southeast University, Nanjing, Jiangsu, China (People's Republic),
3
Electrochemical
Innovation Lab, Department of Chemical Engineering, University College London, London, England,
United Kingdom,
4
Elettra Sincrotrone, Trieste, Piemonte, Italy
* Corresponding author: Andrei.Kolmakov@nist.gov
Many important biological, physical, and chemical processes take place in aqueous environments and thus
warrants the investigation of these systems under realistic conditions. Accessing in-vivo conditions is the
next generation of biological optical, electron and X-ray imaging that will provide valuable insight into
structure-activity relationships of biomolecules within cellular operations [1]. However, the
incompatibility of cells, which subsist in aqueous conditions, with the vacuum environments soft x-rays
and electron spectrometers as well as low dose thresholds for beam damage, impedes the capability of
imaging and spectroscopic studies under physiological conditions. Recent advances in applications of two
dimensional (2D) materials, i.e. graphene, to separate the sample environment from UHV conditions in
the analysis chamber have been made by employing 2D materials as molecularly impermeable, electron
transparent membranes [2]. This approach to examine samples under operational conditions using various
types of microscopies is an attractive method to investigate cellular functions.
Herein we report on development and tests of the multicompartment graphene encapsulated sample
platform designed to be suitable for in-situ studies of biological samples with an array of analytical
methods such as optical/fluorescence/Raman as well as scanning electron and X-ray microscopies. (Figure
1). Low-stress Si3N4 coated silicon wafers were wet etched to form 100 x 100 μm membranes which
comprises the base of the platform. The platform lid was composed of an SU-8 film which was
photolithography patterned with corresponding windows over which graphene layers were transferred.
Samples can be deposited on the Si3N4 window and become encapsulated by the graphene membrane
once the lid is placed on the platform. The conformability of single and multilayer graphene sheets over
the shape of a specimen allows it to be intimately confined and have its environment preserved while
becoming suitable to be studied with conventional analytical techniques [3]. The encapsulation by
graphene minimizes the volume of water retained platforming the probing volume, reducing the
adsorption and scattering cross-section of the sample matrix while still providing cells a hydrating
environment. Implementation of sample immobilization with a biocompatible patternable gel media
allows for an extended cellular lifetime under measurement. Preliminary feasibility tests of graphene
encapsulation of wet samples have been conducted with optical, SEM, TEM, Raman and FTIR
microscopies.
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