Patent ID: 7874211

Claim:
A method where property of a substance contacting to a quartz oscillator equipped with electrodes on both sides of a quartz plate is measured on the basis of the changes in frequency of the above quartz oscillator, characterized in that, the property of the above substance is measured using at least two mode frequencies among the n-th overtone mode frequencies of the quartz oscillator, wherein n=1, 3, 5, . . . , when voltage is applied between the above electrodes and using F 1@N1 , F 2@N1 which are a set of frequencies F 1 , F 2 measured by one n-th overtone mode frequency N1s, wherein F 1 <F 2 , giving one half of the maximum value of conductance near the resonant point by each frequency, and F 1@N1 , F 2@N2 which are a set of frequencies F 1 , F 2 measured by other n-th overtone mode frequencies, N2, wherein F 1 <F 2 giving one half of the maximum value of conductance near the resonant point by each frequency, wherein the values of ω 2 ρ 2 η 2 h 1 /μ 1 and C are determined from the measured value: (ΔF 2@N1 /N1−ΔF 2@N2 /N2)/(Δ(F 1@N1 −F 2@N1 )/2N 1 1/2 −Δ(F 1@N2 −F 2@N2 )/2N 2 1/2 ) wherein ΔF 2@N1 /N1−ΔF 2@N2 is expressed by the expression 9′, and Δ(F 1@N1 −F 2@N1 )/2N 1 1/2 −Δ(F 1@N2 −F 2@N2 )/2N 2 1/2 ) is expressed by the expression 10′: (N1·(1+N1·C)/(1+(N 1 ·C) 2 )−N2·(1+N 2 ·C)/(1+(N 2 ·C) 2 ))·ω 2 ρ 2 η 2 h 1 /μ 1 [Expression 9′] wherein ω is angular frequency, η n is viscosity of the liquid, ρ n is density of the liquid, h n is film thickness and n is n-th layer, (−(N1) 3/2 /(1+(N1·C) 2 )−(N2) 3/2 /(1+(N2·C) 2 ))·ω 2 Σ 2 η 2 h 1 /μ 1 [Expression 10′] wherein ω is angular frequency, η n is viscosity of the liquid, ρ n is density of the liquid, h n is film thickness and n is n-th layer, and after the values of ω 2 ρ 2 η 2 h 1 /μ 1 and C are determined, the mass load, the viscoelasticity term 1, the viscous load and the viscoelasticity term 2 are obtained from the formula 7′, formula 7″, formula 8′ and formula 8″, respectively: the mass load=Δ F 2N /N −(1 +C·N )· Nω 2 ρ 2 η 2 h 1 /μ 1 (1 +C 2 N 2 ) [Formula 7′] wherein ω is angular frequency, η n is viscosity of the liquid, ρ n is density of the liquid, h n is film thickness and n is n-th layer, the viscoelasticity term 1 =ΔF 2N /N 2 +(the mass load)/ N, [Formula 7″] the viscous load=Δ( F 1N −F 2N )/2 ·N 1 1/2 +N 3/2 ω 2 ρ 2 η 2 h 1 /μ 1 ·(1 +C 2 N 2 ) [Formula 8′] wherein ω is angular frequency, η n is viscosity of the liquid, ρ n is density of the liquid, h n is film thickness and n is n-th layer, the viscoelasticity term 2=Δ( F 1N −F 2N )/2 ·N 2 +(the viscous load)· N. [Formula 8″]