Fabrication of fully suspended pyrolytic carbon string resonators for characterization of drug nano- and microparticles

Pyrolytic carbon is a promising material for fabrication of micro- and nanomechanical sensors due to thepossibility to control both structural parameters and properties such as resonance frequency, residualstress and electrical conductivity. Here, we present a novel fabrication process for pyrolytic carbon stringresonators suspended over a through-wafer-orifice. The pyrolytic carbon string resonators had a length of400 μm, a width of 30 μm and a thickness of 700 nm. The string resonators were applied for characterization of nano- and microparticulate drug formulations using two different modes of operation. First, mass-sensing on nanograms of nebulized or spray coated paracetamol micro- and nanoparticles was demon-strated. Then, absorption spectra of the drug were obtained by nanomechanical infrared spectroscopy(NAM-IR). Finally, an efficient method for in situ regeneration of the sensor was demonstrated.