A novel concept for low drift chemical sensing at micro and nano-scale

It is the purpose of this paper to present a novel generic concept for low drift chemical sensing which is applicable at micro and nanometer scale, based on a new, all-differential approach. At micrometer level, our principle is explained by means of surface acoustic wave (SAW) chemical sensing, while at nano level, we are using the resonant sensing principle to develop our genuine differential concept. Unlike the traditional differential approaches based on functionalized sensing layer in the sensing loop, and on a uncoated surface in the reference loop, our all differential concept provides a better response subtraction between the two paths, as the sensing loop consists of a functionalized sensing layer, as before, but, the reference loop consists of a functionalized non-sensing layer, with the same ageing and humidity behavior as the sensing layer. Twinned electronic reading is used for both loops, and thus all the common mode signals are subtracted in the differential reading, assuring the minimum base line drift of the sensor. Preliminary results of all differential sensor response to humidity and temperature variations are shown for the SAW sensors, with the sensor signal kept independent of their changes.