Dual-response resonant chemical sensors for multianalyte analysis

We developed an approach to increase the information content from resonant, thickness-shear mode (TSM) sensors. These sensors are intended for integration into a microanalytical system that will periodically collect and precondition a predetermined volume of sample and will further present it to the sensor for analysis. Each side of the TSM resonator is coated with a different sensor film. During measurements, only one side at a time is exposed to an analyzed vapor while another side is exposed to a blank gas from a scrubber. Thus, analyte-related signals are generated independently from each side of the TSM sensor. Such dual-response sensing approach reduces the number of sensing elements by a factor of two, leading to further system miniaturization and improved power budget in sensor operation. We demonstrated our dual-response sensor concept with a high-performance, low noise TSM resonator (f0 = 107 Hz, RMS noise <0.05 Hz) arranged in a low volume (<200 μL) dual flow cell. With a single resonator, we successfully discriminated and quantified toxic industrial and environmental concern vapors such as toluene and trichloroethylene and two isomers of dichloroethylene (DCE) such as cis-1,2-DCE and trans-1,2-DCE.