$A_1$	area of the microneedle bottom (m2)
$B_0$	relaxed force (Equation (10)) (N)
$B_i, i=1, 2, \cdots$	proportional constants (Equation (10)) (N)
$c$	compliance of the force transducer (m/N)
$C_0$	$\mathrm{is}\mathrm{related}\mathrm{to}{B}_0$
$C_i, i=1,2, \cdots$	proportional constants (Equation (9)) (N)
$CoD$	coefficient of determination
$E$	Young’s modulus (Pa)
$E_0$	instantaneous Young’s modulus (Pa)
$E_{\infty }$	long-term Young’s modulus (Pa)
${\widehat{F}}_i$	predicted force from models (N)
$F_i$	the ith force (N)
$F\left(t\right)$	time-dependent force (N)
$G$	shear modulus (Pa)
$G_0$	instantaneous shear modulus (Pa)
$G_{\infty }$	long-term shear modulus (Pa)
$G\left(t\right)$	time-dependent shear modulus (Pa)
$h_0$	height of the microneedle (m)
$h^{\prime }$	height of the missing tip assuming the microneedle is perfectly sharp (m)
$n$	degree number in the viscoelastic analysis
$N$	number of data points during the holding
$r_1$, $r_2$	half side length of a quadrangular microneedle base and tip (m)
$t$	time (s)
$t_R$	rising time (time taken to compress a microneedle) (s)
$t_s$	acquisition time (sampling time) (s)
$V$	compression speed (m/s)
Greek Symbols
$\delta$	displacement (m)
${\delta }_0$	maximum displacement before relaxation (m)
${\tau }_i, i=1, 2, \cdots$	relaxation times (s)
${\mathsf{\Phi }}_{\mathrm{i}}, i=1, 2, \cdots$	ramp correction factors (Equation (13))
$\nu$	Poisson’s ratio