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Flexural mode vibrations of miniature piezoelectric tuning forks (TF) areknown to be highly sensitive to superfluid excitations and quantum turbulencein $\mathrm{^3He}$ and $\mathrm{^4He}$ quantum fluids, as well as to theelastic properties of solid $\mathrm{^4He}$, complementing studies by largescale torsional resonators. Here we explore the sensitivity of a TF, capable ofsimultaneously operating in both the flexural and torsional modes, toexcitations in the normal and superfluid $\mathrm{^4He}$. The torsional mode ispredominantly sensitive to shear forces at the sensor - fluid interface andmuch less sensitive to changes in the density of the surrounding fluid whencompared to the flexural mode. Although we did not reach the critical velocityfor quantum turbulence onset in the torsional mode, due to its order ofmagnitude higher frequency and increased acoustic damping, the torsional modewas directly sensitive to fluid excitations, linked to quantum turbulencecreated by the flexural mode. The combination of two dissimilar modes in asingle TF sensor can provide a means to study the details of elementaryexcitations in quantum liquids, and at interfaces between solids and quantumfluid.

Multimode probing of superfluid $\mathbf{^4He}$ by tuning forks