title: Infrared microspectroscopy combined with conventional atomic force microscopy.
abstract: This paper reports nanotopography and mid infrared (IR) microspectroscopic imaging coupled within the same atomic force microscope (AFM). The reported advances are enabled by using a bimaterial microcantilever, conventionally used for standard AFM imaging, as a detector of monochromatic IR light. IR light intensity is recorded as thermomechanical bending of the cantilever measured upon illumination with intensity-modulated, narrowband radiation. The cantilever bending is then correlated with the sample's IR absorption. Spatial resolution was characterized by imaging a USAF 1951 optical resolution target made of SU-8 photoresist. The spatial resolution of the AFM topography measurement was a few nanometers as expected, while the spatial resolution of the IR measurement was 24.4 μm using relatively coarse spectral resolution (25-125 cm(-1)). In addition to well-controlled samples demonstrating the spatial and spectral properties of the setup, we used the method to map engineered skin and three-dimensional cell culture samples. This research combines modest IR imaging capabilities with the exceptional topographical imaging of conventional AFM to provide advantages of both in a facile manner.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: B
authors.initials: B
authors.lastname: Kwon
authors.forename: M V
authors.initials: MV
authors.lastname: Schulmerich
authors.forename: L J
authors.initials: LJ
authors.lastname: Elgass
authors.forename: R
authors.initials: R
authors.lastname: Kong
authors.forename: S E
authors.initials: SE
authors.lastname: Holton
authors.forename: R
authors.initials: R
authors.lastname: Bhargava
authors.forename: W P
authors.initials: WP
authors.lastname: King
mesh_terms: D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015603:Keratinocytes / Q000166:cytology; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods*; D012867:Skin / Q000033:anatomy & histology; D013055:Spectrophotometry, Infrared / Q000295:instrumentation / Q000379:methods*; D023822:Tissue Engineering