The responses of smooth- and textured-surface thickness-shear mode (TS
M) resonators in liquid are examined. Smooth devices, which viscously
entrain a layer of contacting liquid, exhibit a response that depends
on the product of liquid density and viscosity. Textured-surface devic
es, which also trap liquid in surface crevices, pores, etc., exhibit a
n additional response that depends on liquid density alone. Combining
smooth- and textured-surface resonators in a monolithic sensor enables
the liquid density and viscosity to be extracted simultaneously.