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. 2021 May 17;21(10):3490. doi: 10.3390/s21103490
Variable Definition
~ Tilde: a complex parameter
^ Hat: a complex amplitude
Aeff Effective area of the resonator Aeff=nπ32Zqd262f0 2GmaxQ (A1)
C0 Resonator’s electrical capacitance (parallel capacitance) C0=εqε0Aelectrodedq (A2)
C1 Motional capacitance C1 = 8ϕ2nπAeffZq12πnf0     with     ϕ = Aeffd26dq
C1 = 8kt,eff2(nπ)2C0     with     kt,eff2  0.8%
(A3)
D Dissipation factor D=1Q=2Γfres (A4)
G˜ Shear modulus G˜=G+iG=1/J˜=(JiJ)1 = iωη˜G˜=|G|(cos(δL)+isin(δL))
tan(δL) = G/G = J/J
(A5)
Gq Shear modulus of AT-cut quartz Gq ≈ 29 × 109 Pa
J˜ Shear compliance J˜=1/G˜=(JiJ) (A6)
L1 Motional inductance L1=14ϕ2Aeffmq2      ϕ=Aeffe26dq (A7)
Q Quality factor Q=fres2Γ (A8)
R 1 Motional resistance,
the inverse of Gmax (Equation (13))
Z˜ Shear-wave impedance Z˜=ρc˜=ρG˜=iωρη˜=iη˜k˜ω (A9)
Z˜L Load impedance Z˜L=σ^Sv^S (A10)
Zq Shear-wave impedance of AT-cut quartz Zq = 8.8 × 106 kg m−2 s−1
c˜f, cq, c˜bulk Speed of shear sound c˜=G˜/ρ
d26 Piezoelectric strain coefficient of AT-cut quartz d26 = 3.1 × 10−12 m/V
e26 Piezoelectric stress coefficient of AT-cut quartz e26= d26Gq = 9.65 × 10−2 C/m2
df, dq Thickness of film and resonator
k˜f, kq, k˜bulk Wave vector in the film, the resonator plate, and the bulk k˜bulk=ωc˜bulk=ωρbulkiηbulk=2i1δ=(1i)ωρbulk2ηbulk (A11)
kt Electromechanical coupling
coefficient
kt,ideal2= e26εqε0Gq
kt,eff2=C1C0(nπ)28
(A12)
fcen A frequency in the center of the QCM’s frequency range (Section 4.7)
fref Resonance frequency in reference state
fres Resonance frequency fres=nf0
f0 Fundamental frequency f0=Zq2mq
mf , mq Mass per unit area of the film and the resonator plate mq=ρqdq=Zqλ2=12Zqcqf0=Zq2f0 (A13)
mR Effective mass of a resonator parallel plate: mR=Aeffmq2 (A14)
n Overtone order
nP Number of particles in contact with the resonator
nr Refractive index
u, u^
 uS, u^S
Displacement,
amplitude of displacement (^)
subscript S: at the surface
u^=v^iω      v^S=dq2e26AeffI^ (A15)
 v, v^, vS, v^S Velocity, amplitude of velocity (^) v^=iωu^ (A16)
β, β
γ, γ
Power law exponents,
Section 4.7
Jf(f)  Jf(fcen)(ffcen)β
Gf(f)  Gf(fcen)(ffcen)γ
Jf(f)  Jf(fcen)(ffcen)β
Gf(f)  Gf(fcen)(ffcen)γ
(A17)
η˜ Viscosity η˜=G˜iω=ηiη (A18)
Γ Imaginary part of resonance
frequency, half-band half width
ΔR+iΔX Load impedance in electrical units
(in older publications)
ΔR+iΔX=Aeff4ϕ2Z˜L=iπ16Zq3Aeffe262εq2f03(Δf+iΔΓ) (A19)
εq Dielectric constant of AT-cut quartz εq = 4.54
κR Effective spring constant κR=AeffGqdq(nπ)22=(nπ)22κq,stat (A20)
ρq Density of α-quartz ρq = 2.65 × 103 kg/m3
σ, σ^, σS, σ^S Tangential stress, amplitude thereof
ξR Effective drag coefficient