Handheld Force Controlled Ultrasound Probe

An actuated handheld force-feedback controlled ultrasound probe has been developed. The controller maintains a prescribed contact force between the probe and a patient’s body. The device will enhance the diagnostic capability of free-hand elastography, swept-force compound imaging and make it easier for a technician to acquire repeatable (i.e., directly comparable) images over time. The mechanical system consists of an ultrasound probe, a ball-screw-driven linear actuator, and a force/torque sensor. The feedback controller commands the motor to rotate the ball screw to translate the ultrasound probe in order to maintain a desired contact force. In preliminary user studies, it was found that the control system maintained a constant contact force with 1.7 times less variation than human subjects provided with a visual force display. Users without a visual force display were only able to maintain a constant force with 20 times worse variation than the automatic controller. The system was also used to determine the viscoelastic properties of soft tissues.