a	half of the width of the microchannel, μm
$A_{tr}$	total effective convective heat transfer area, ${\mathrm{m}}^2$
b	half of the height of the microchannel, μm
$c_f$	fluid specific heat capacity, J/kg$·$°C
$D_c$	distance of two adjacent cavities, μm
$D_{ch}$	hydraulic diameter of microchannel, μm
fapp	apparent friction coefficient
$f_{\mathrm{app},0}$	friction factor of the straight microchannel
$F\left(a/b\right)$	function depended on a/b
h	local convective heat transfer coefficient, $\mathrm{W}/({\mathrm{m}}^2·$°C)
$h_{fin}$	fin surface heat transfer coefficient, $\mathrm{W}/({\mathrm{m}}^2·$°C)
$H_{ch}$	height of microchannel, μm
$K_{90}$	pressure loss coefficient for a 90° bend
$K_c$	sudden contraction coefficient
$K_e$	sudden expansion coefficient
$K_{im}$	inlet manifold loss coefficient
$K_{om}$	outlet manifold loss coefficient
$L_{ch}$	length of microchannel, mm
N	number of parallel microchannels
Nu	Nusselt number
${Nu}_0$	Nu number of the straight microchannel
m	fin parameter
${\dot{m}}_f$	fluid mass flux, $\mathrm{kg}/\mathrm{s}$
q	heat flux, $\mathrm{W}/{\mathrm{m}}^2$
$\Delta P_c$	pressure drop caused by sudden contraction, Pa
$\Delta P_{ch}$	pressure drop in the microchannel, Pa
$\Delta P_e$	pressure drop caused by sudden expansion, Pa
$\Delta P_{im}$	pressure drop in the inlet manifold, Pa
$\Delta P_{loss}$	pressure loss, Pa
$\Delta P_{om}$	pressure drop in the outlet manifold, Pa
$\Delta P_{total}$	total pressure drop between inlet/outlet manifold, Pa
R	radius of reentrant cavities, μm
Re	Reynolds number
$T_{ave}$	average of the temperature measured by the four thermocouples, °C
$T_f$	fluid characteristic temperature, °C
$T_{f,in}$	fluid inlet temperature, °C
$T_{f,out}$	fluid outlet temperature, °C
$T_w$	Wall temperature, °C
V	total fluid volumetric flow rate
$V_{ch}$	average velocity in the microchannel, m/s
$V_{im}$	velocity in the inlet manifold, m/s
$V_{om}$	velocity in the outlet manifold, m/s
$W_{ch}$	width of microchannel, μm
Greek letters
$\alpha$	dimensionless parameter, (=R/$D_{ch}$)
$\beta$	dimensionless parameter, (=R/$D_c$)
${\rho }_f$	fluid density, $\mathrm{kg}/{\mathrm{m}}^3$
${\mu }_f$	fluid dynamic viscosity, Pa$·$s
${\lambda }_f$	fluid thermal conductivity coefficient, W/m$·$°C
${\lambda }_{Si}$	thermal conductivity coefficient of silicon, W/m$·$°C
$\eta$	overall performance factor
${\eta }_{fin}$	fin efficiency
$\sigma$	area ratio