21. To meet the resolution requirements of manipulating single cells, short-wavelength acoustic waves should be employed. 22. Other types of delay line include acoustic ( usually magnetostrictive, and surface acoustic wave devices. 23. We note that acoustic waves of 100 GHz to 1 THz have wavelengths in nanometre range. 24. Like capacitive screens, acoustic wave screens are robust. 25. Surface acoustic wave humidity sensors require a thermoelectric cooler in addition to a surface acoustic wave device. 26. As an acoustic wave propagates through the tissue, part of it is absorbed and converted to heat. 27. With megasonics, the acoustic wave is found only in a line of sight from the transducer surface. 28. Surface acoustic wave humidity sensors require a thermoelectric cooler in addition to a surface acoustic wave device. 29. Acoustic waves themselves are waves of mechanical motion : of air molecules or some other fluid medium.30. Surface acoustic wave devices can be used to measure changes in viscosity of a liquid placed upon it.