Device for detecting interaction with an object
A device and method for the detection of the interaction between two or more objects is disclosed. The device utilizes electrical impedance spectra measured from a piezoelectric element attached to one such object. Comparison of such spectra along a range of traverse allows precise estimates of distance to be made. One useful application is the topographical mapping of a surface.
1. 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; and
measuring the electrical properties of said piezoelectric element while said contact object is interacting with said target object and recording those properties.
2. The method of claim 1 , wherein said physical interaction is physical contact between said contact object and said target object.
3. The method of claim 1 , wherein said physical interaction is a liquid bridge between said contact object and said target object.
4. 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; and
comparing the electrical properties with previously calibrated values to determine when interaction between said contact object and target object has occurred.
5. The method of claim 4 , wherein said physical interaction is physical contact between said contact object and said target object.
6. The method of claim 4 , wherein said physical interaction is a liquid bridge between said contact object and said target object.
7. The method of claim 4 wherein the steps thereof are carried out a plurality of times at different locations on a substrate, whereby to topologically map surface imperfections and determine cant of the substrate.
8. The method of claim 4 , further comprising the steps of:
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.