Milliwatt mixer for small fluid samples

Mixing without excessive heating is sometimes needed for temperature-sensitive fluids. An inexpensive low-frequency electronic filter based on a mechanical resonator to produce a compact (16 mm) and low-power (1-3 mW) mixer for low viscosity fluids is developed. Tests made in air and methanol at room temperature and in fluoroform near its critical point are compared against the predictions of an electromechanical model.