Poly(Dimethylsiloxane) Waveguide Cantilevers for Optomechanical Sensing

The optical and structural properties of poly(dimethylsiloxane) (PDMS) are considered to define disposable cantilever-based micooptoelectromechanical systems (MOEMS) by ways of soft lithography and with a high degree of monolithic integration. The very low Young's modulus of this material relaxes the dimensions' requirements, being then possible to define thick PDMS structures with a sensitivity comparable to nanometer scale silicon counterparts. Experimental results using a light-emitting diode working at 670 nm have determined the resonant frequencies of the proposed MOEMS and are in agreement with the numerical simulations done. Finally, when a 2-$\mu$ L droplet of ethanol (1.58 mg) is dispensed on the cantilever, relative losses rise to 25 dB, returning to its initial value when the droplet evaporates.