Multiple-frequency acoustic wave devices for chemical sensing and materials characterization in both gas and liquid phase

An acoustic wave chemical or physical sensor, comprising:

• (a) a substrate of material suitable for supporting an acoustic wave having a specific frequency therein;
• and
• (b) a plurality of input electrodes and a plurality of output electrodes disposed upon a surface of said substrate, where an input electrode comprising one electrode of said plurality of input electrodes corresponds to an output electrode comprising one electrode of said plurality of output electrodes to form an interdigitated pair, each component of said pair of interdigitated electrodes, said input electrode and said output electrode being responsive to generating and receiving respectively an acoustic wave having a distinct frequency range and a measurable amplitude for coupling a response of an acoustic wave to changes introduced in an interactive region:
• (c) an interaction region defined by all of said paired electrodes where said interaction region is bounded on one side by said plurality of input interdigitated electrodes and on the other side by a plurality of said output interdigitated electrodes said input and said output interdigitated electrodes being spaced apart from one another upon the surface of said substrate;
• (d) a plurality of oscillator circuit means for generating and receiving signals where a distinct oscillator means of said plurality generates and receives signals which fall within said distinct frequency range and where said distinct oscillator means couples said input electrode to said output electrode of a distinct pair of electrodes where said input interdigitated electrode is responsive to a generating signal from said oscillator means and where said output interdigitated electrode of said pair produces a receiving signal in response to a perturbed acoustic wave, said interaction region being a region where the presence of a chemical species or changes in the intrinsic physical properties of a thin film causes a detectable change in said frequency of said acoustic wave and/or an attenuation of said acoustic wave coupled between a pair of said interdigitated electrodes.

An acoustic wave chemical or intrinsic physical property sensor comprising:

• (a) a substrate suitable for supporting acoustic waves therein;
• (b) a thin film sensitive to the presence of a chemical or a physical stimulus disposed on said substrate;
• (c) an interaction region encompassing said thin film on said substrate where the presence of said stimulus changes properties of said thin film which causes a detectable change in the velocity and/or an attenuation of an acoustic wave which transverses the film;
• and
• (d) a plurality of paired input and output means disposed upon said substrate where each of said paired input and output means comprising said plurality has a distinct periodicity different from each of said other paired input and output means, where an input means of said pair is responsive to a means for generating acoustic waves where said generating means transmits a signal having a distinct frequency based on the periodicity of said input means to said input means, wherein said plurality of input means provides acoustic waves having multiple distinct frequencies to said interactive region, and said plurality of output means receives acoustic waves which have undergone a phase shift and/or a change in amplitude due to the presence of said stimulus in said interaction region and provides a response which is indicative of said shift or change an output measuring means, whereby each individual one of said paired input means has a corresponding output means, where each of said pairs is responsive to acoustic waves having distinct and different acoustic frequencies and where said output measuring means is coupled to said acoustic wave generating means and to a computing means for detecting a perturbation in acoustic wave velocity and an attenuation of said acoustic wave as a function of frequency to determine chemical or intrinsic physical properties of said stimulus.

A method of operating a multiple frequency chemical or intrinsic physical property sensing means, comprising the steps of:

• (a) applying, from a multiple frequency source having multiple distinct frequency signals, a distinct frequency signal to each of a plurality of individual input means of the sensor;
• (b) generating an acoustic wave having a distinct frequency specific to each input means comprising said plurality, said sensor having an individual output means corresponding to each individual input means wherein there is a one to one correspondence from each said individual input means to said individual output means forming a paired input and output means wherein an interaction region is defined between said input and output means;
• (c) exposing said interaction region of said sensor to a chemical or physical stimulus that will change said specific frequency and/or said specific amplitude of said generated acoustic wave;
• and
• (d) receiving said generated acoustic wave at said paired output means, wherein each of said output means is at least responsive to the distinct frequency signal applied to its corresponding input means;
• (e) determining a velocity and a amplitude perturbation for said acoustic wave between said generation and said reception as a function of frequency;
• (e) analyzing said perturbations over a plurality of frequencies to determine chemical or intrinsic physical properties associated with said exposure of said interactive region to said chemical or physical stimulus.