Indium Phosphide MEMS Cantilever Resonator Sensors Utilizing a Pentacene Absorption Layer

We report a microelectromechanical system cantilever waveguide resonator sensing platform utilizing a novel optical readout scheme and the organic semiconductor pentacene as a surface absorbing layer. In this paper, the measurement of isopropyl alcohol and ethanol vapors by way of mass induced frequency shift using a cantilever microbalance is demonstrated. Vapor was introduced to the system through a custom built environmental chamber. A frequency shift due to a mass absorption of 65 Hz was measured, corresponding to a measurement of 6.92 ±1.1 ×10
^-14
g with a minimum detectable mass of 5.09 ×10
^-15
g for the devices presented. The pentacene absorbing layer in this paper shows it for the first time, functioning as a mass absorbing layer. These results are also the first demonstration of repeatable mass sensing performed using the integrated indium phosphide cantilever waveguide sensor platform.