The PI 95 TEM PicoIndenter from Hysitron, Inc. is the first full-fledged depth-sensing indenter capable of direct-observation nanomechanical testing in a transmission electron microscope (TEM). This pioneering in-situ instrument is specifically designed to overcome the numerous configurational and environmental challenges presented by transmission electron microscopes, and its primary function is to output a quantitative force-displacement curve to be time correlated to the corresponding transmission electron microscope movie of the stress-induced deformation process. This coupling of high-resolution techniques enables a researcher to witness, for example, the microscopic origin of a measured force or displacement transient. 

The key enabling technology of the PI 95 TEM PicoIndenter instrument is its novel miniature transducer. With this newly-developed transducer, in-situ force-displacement curves can be acquired in a highly accurate depth-sensing manner, instead of relying on an inherently troublesome series-loading, spring-deflection-force scheme. Furthermore, substantially larger forces can be realized on account of the electrostatic actuation aspect of the transducer, without suffering a force sensitivity penalty. Control of the transducer, and of the piezoelectric actuator, is governed by a newly-developed advanced digital controller operating at a high loop rate. 

• Patent-pending miniature transducer providing electrostatic actuation and capacitive displacement sensing
• Tranmission electron microscope holder equipped with a three-axis coarse positioner and a 3D piezoelectric actuator for fine positioning
• Advanced digital controller utilizing a digital signal processor (DSP)
• Multiple operating modes including closed-loop displacement control, open-loop load control, and closed-loop force-balance control
• Actively damped transducer when operating under closed-loop control
• Easily interchangeable conductive probes and explicit means for preventing probe charging

PI 95 PicoIndenter in-situ video of CdS nanosphere indentation