Photothermal analysis of individual nanoparticulate samples using micromechanical resonators

Tom Larsen, Silvan Schmid, Luis Guillermo Villanueva Torrijo, Anja Boisen

    Research output: Contribution to journalJournal articleResearchpeer-review


    The ability to detect and analyze single sample entities such as single nanoparticles, viruses, spores, or molecules is of fundamental interest. This can provide insight into the individual specific properties which may differ from the statistical sample average. Here we introduce resonant photothermal spectroscopy, a novel method that enables the analysis of individual nanoparticulate samples. Absorption of light by an individual sample placed on a microstring resonator results in local heating of the string, which is reflected in its resonance frequency. The working principle of the spectrometer is demonstrated by analyzing the optical absorption of different micro- and nanoparticles on a microstring. We present the measurement of a simple absorption spectrum of multiple polystyrene microparticles illuminated with an unfocused LED light source. Using a diode laser, single 170 nm polystyrene nanoparticles are detected. With the current setup, nanoparticulate samples with a mass of ∼40 ag are detectable. By using nanostrings, visible and infrared photothermal spectroscopy in the subattogram mass regime is possible and single molecule detection is within reach. © 2013 American Chemical Society.
    Original languageEnglish
    JournalACS Nano
    Issue number7
    Pages (from-to)6188-6193
    Publication statusPublished - 2013


    • Absorption spectroscopy
    • Laser spectroscopy
    • Light absorption
    • Light sources
    • Micromechanical resonators
    • Molecules
    • Nanoparticles
    • Polystyrenes
    • Resonators
    • Viruses
    • Light emitting diodes


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