Millimeter wave bioeffects at 94 GHz on skeletal muscle contraction

Many reports on the use of millimeter waves in clinical applications involve non-thermal bioeffects produced by frequencies as high as 77.7 GHz. In addition, there is the well-known thermal effect of intense skin heating used in non-lethal weapon systems operating at 94 GHz. We investigated the possibility of non-thermal bioeffects at 94GHz on skeletal muscle contraction. Using a custom-designed exposure system we measured contraction of flexor digitorum brevis, a fast-twitch muscle obtained from mouse toe, during millimeter wave exposures. Electric field magnitudes in excess of 2.6 kV/m were observed to cause a reproducible decrease in force production in the absence of measurable changes in temperature.