Method and apparatus for analyzing spatial and temporal processes of interaction

#The invention generally relates to the field of chemical or biological agent detection. In particular, in one embodiment, the invention relates to a device for interpreting sensor readings to determine the concentration of an agent in a fluid environment, and the design and operation thereof.

#A chemical sensor typically includes a vibrating membrane having a polymer coating that is capable of being loaded with vapors and interferents. As the vapor loading takes place, the mass carried by the membrane increases causing a shift in its vibration frequency. The frequency shift is a function of the type and amount of vapors loaded. In general, more than one vapor can load onto each polymer coating, but some coatings have a stronger affinity for particular vapors.

#Normally, an array of sensors, each having a distinctive polymer coating, is used together; the vibration frequency of each membrane is measured and recorded. An array is usually selected to optimize a certain performance criterion of interest, such as maximizing the probability of detecting a lethal vapor of interest or minimizing the probability of false alarms. Signals representative of the vibration frequencies of an array of sensors can be interpreted to determine concentration levels of vapors present in the atmosphere.

#The following drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:

#FIG. 1 is an illustration of physical components and processes that an exemplary model may describe in various embodiments of the invention;

#FIG. 2A is a schematic representation of interacting entities-reagent molecule B at a site on a sensor plate and molecules at sites in the air surrounding the plate site;

#Embodiments of various aspects of the invention are described below. Other embodiments incorporating the concepts disclosed herein are within the spirit and scope of the invention. The described embodiments are to be considered in all respects as only illustrative and not restrictive.

#FIG. 1 depicts a sensor 100 that may be used in conjunction with, or incorporated into, the present invention. In particular, FIG. 1 depicts a flexural plate wave (FPW) sensor 100 in which the flexural plate is made of Silicon and coated with thin film piezoelectric drive and sense comb fingers on one surface. The drive comb fingers drive the plate with a sinusoidal voltage. The sense comb fingers sense the vibration frequency of the plate. An electronic circuit locks on to the resonant frequency. The opposite surface of the Silicon flexural plate is coated with a reagent. When the reagent absorbs an agent that is present in the environment, the mass of the flexural plate increases causing a shift in the vibration frequency of the plate. The concentration of an agent is estimated by interpreting the sensor readings.

#Preferably, the FPW sensor 100 of FIG. 1 is placed in a gas environment and the agent is a gas vapor. Nonetheless, the FPW sensor 100 of FIG. 1 also works under the same operating principle in a liquid environment by absorbing a liquid analyte. Thus, the invention can be implemented and used in a liquid environment.