# US 7,849,738 B2 · Device for detecting interaction with an object

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- Number: US 7,849,738 B2
- Document ID: US7849738B2
- Status: Granted
- Kind: B2
- Application number: 11/716,097
- Filed: 2007-03-09
- Published: 2007-09-13
- Granted: 2010-12-14
- Earliest claimed: 2006-03-13
- Assignees: Sonoplot, Inc.
- Inventors: Bradley James Larson; Joerg Werner Baier
- Web page: https://patentgrep.com/patent/US7849738B2

## CPC

- B01L 3/0268: {using pulse dispensing or spraying, eg. inkjet type, piezo actuated ejection of droplets from capillaries}
- G01N 35/1011: {Control of the position or alignment of the transfer device}
- B01L 2200/143: Quality control, feedback systems
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

The method of claim 1, wherein said physical interaction is physical contact between said contact object and said target object.

### Claim 3 (depends on 1)

The method of claim 1, wherein said physical interaction is a liquid bridge between said contact object and said target object.

### Claim 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.

### Claim 5 (depends on 4)

The method of claim 4, wherein said physical interaction is physical contact between said contact object and said target object.

### Claim 6 (depends on 4)

The method of claim 4, wherein said physical interaction is a liquid bridge between said contact object and said target object.

### Claim 7 (depends on 4)

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.

### Claim 8 (depends on 4)

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.