Patent ID: 7555952

Claim:
A sensing device for sensing objects in a medium, comprising: resonator elements each having an adsorbing surface configured to adsorb an object to be measured from said medium, and a natural frequency determined by absence or presence of an object adsorbed on said adsorbing surface; oscillation circuits, each of said oscillation circuits having an oscillation output, and an input connected to a respective one of said resonator elements so as to produce an oscillation signal having an oscillation frequency determined at least in part by said natural frequency of said connected one of said resonator elements and loading at said oscillation output; a measuring unit having a signal measurement input and a measurement output, said measuring unit being configured to measure an oscillation frequency of an oscillation signal of said oscillation signals applied to said signal measurement input; a signal switching unit connected to said oscillation circuits, said signal switching unit being configured to selectively connect said oscillation outputs to said measuring unit such that individual ones of said oscillation signals produced by said oscillation circuits are successively applied to said signal measurement input; load switching units and terminals loads, each of said oscillation circuits having said oscillation output connected to a respective one of said load switching units, said load switching units being configured to selectively connect said oscillation output to a respective one of said terminal loads; said terminal loads having a sufficient loading value such that, when applied to said oscillation outputs of said oscillation circuits by said load switching units, said terminal loads shift said oscillation frequencies an amount sufficient to prevent spectrum overlap with said oscillation frequencies of other ones of said oscillation circuits without said terminal loads applied to said oscillation outputs; and a switching controller configured to control said signal switching unit and said load switching units such that: said signal switching unit successively connects said oscillation outputs one output at a time to said measuring unit to effect one connection at a time; said load switching units do not apply an associated one of said terminal loads to said one output of said oscillation outputs when said one output of said oscillation outputs is connected to said measuring unit; and said load switching units apply an associated one of said terminal loads to at least one of said oscillation outputs when said at least one of said oscillation outputs is not connected to said measuring unit.