Calibration of beam deflection produced by cellular forces in the 10−9–10−6 gram range

An experimental procedure and method of analysis are presented for calibration of a thin-beam force transducer. The beam transducer can be produced and calibrated with a minimum coefficient of 10 ng (10⁻⁵ dyne) force per micron (10⁻⁴ cm) deflection, i.e.,k _B∼0.1 dyne/cm. Since beam deflections on the order of 0.1 μm can be detected, forces of a few nanograms can be resolved. Such forces are common in mechanical experiments on microscopic bodies, e.g., biological cells, artificial membrane capsules, droplets, etc.