Device for detecting interaction with an object

A method of detecting fluid in a hollow vessel comprising

• providing a hollow substantially round tubular structure adapted to contain a liquid having an inner and an outer wall, said structure having a piezoelectric element attached to said outer wall, and an operable electrical connection to means for measuring the electrical properties of said element
• filling or draining incremental fluid volumes from said tubular structure
• measuring the electrical properties of said piezoelectric element at more than one applied alternating current frequency at each increment, and
• correlating the electrical properties with the fluid volumes so filled or drained.

A method of calibrating the detection of the physical interaction of two or more objects comprising

• attaching a piezoelectric element to a contact object having an operable electrical connection to means for measuring the electrical properties of said element
• mounting said contact object on a positioning device whereby the position of said contact object can be directed incrementally in at least one dimension along a substantially rectilinear path of traverse
• placing a target object in the path of traverse of said contact object
• measuring the electrical properties of said piezoelectric element at more than one applied alternating current frequency without interacting said contact object with said target object and recording those properties
• advancing said contact object along the path of traverse until interaction occurs between said contact object and said target object
• measuring the electrical properties of said piezoelectric element while said contact object is interacting with said target object and recording those properties.

A method of detecting the physical interaction physical interaction of two or more objects comprising

• attaching a piezoelectric element to a contact object having an operable electrical connection to means for measuring the electrical properties of said element
• mounting said contact object on a positioning device whereby the position of said contact object can be directed incrementally in at least one dimension along a substantially rectilinear path of traverse
• advancing said contact object incrementally along the path of traverse in the direction towards said target object
• measuring the electrical properties of said piezoelectric element at each such incremental position
• comparing the electrical properties with previously calibrated values to determine when interaction between said contact object and target object has occurred
• on interaction of the contact object and target object, reversing the direction of path traverse of said contact object
• retreating from the point of interaction incrementally in smaller increments than the advancing increment, and
• comparing the electrical properties with previously calibrated values to determine when interaction between said contact object and target object is no longer occurring.