Remember, the x,y, and z actuators are piezoelectric actuators (Δ pressure by Δ electric field or Δ electric field by Δ pressure).A response curve of one of these actuators sold by Newport optics company is seen in the graph at right.

Assume we are talking about the x-piezo:

Approximately what range of voltage is necessary to achieve a 20 micron scan range?

Piezoelecticity

These may be naturally occuring piezoelectric crystals such as quartz (SiO2).

These appear to be manufactured piezoelectric crystals such as lead zirconate titanate (PZT).

piezoelectric crystal drawings drawings by W.T. Neff

This is z height plotted as colors or shades of grey. It could also be plotted as voltage sent to the z piezo.

Approximately how much higher is this dna molecule than the background it is on?

3D rendering of same type of topography data seen at top right.

Above is a view of an AFM tip as if you were looking up from the sample (from MikroMasch company). The z-resolution in AFM is defined by the feedback loop and the z-piezoelectric actuator. The x/y resolution is defined by x/y actuators (not in the feedback loop) and the shape and size of the tip (see above middle). x/y detail is less reliable than z for this reason.

Which of these 3 image points is highest in the object ?

To make AFM probes, start with a large (4 inch maybe) Si wafer and use photolithographic techniques to remove selected material. Essentially ‘sculpting’ our probe from a piece of bulk silicon (with other materials). This is the same technology that makes transistors on computer chips. The more computer chips or afm tips we can get from one wafer of Si, the cheaper they become (top drawing of alternate method that still involves lithography and silicon is from ThermoMicroscopes company).

From PNI manual

http://www.sensortech.ca/

Piezoelectricity (from: pressure electricity) is a property of certain classes of crystalline materials including natural crystals of Quartz, Rochelle Salt and Tourmaline plus manufactured ceramics such as Barium Titanate and Lead Zirconate Titanates (PZT).When mechanical pressure is applied to one of these materials, the crystalline structure produces a voltage proportional to the pressure. Conversely, when an electric field is applied, the structure changes shape producing dimensional changes in the material.The piezoelectric materials from Morgan Electro Ceramics use polycrystalline ceramics instead of natural piezoelectric crystals. These are more versatile with physical, chemical and piezoelectric characteristics able to be tailored to specific applications. The hard, dense ceramics can be manufactured in almost any given shape or size. They are chemically inert, and immune to moisture and other atmospheric conditions.Morgan Electroceramic, as part of a group which is a world leader in Advanced Ceramics, has piezoelectric R&D and manufacturing facilities in Southampton, England; Ruabon, Wales and Bedford, Ohio.Historical Note:The Piezoelectric effect was discovered byPierre Curie (1859-1906) in the early 1880's.

Silicon AFM probe x

y

z

xy

z

Final tip radius can be <1nm. Often tip damage and contamination make this tip radius much larger than 1nm (see below)

www.ipht-jena.de/typo3temp/pics/8a3180fa14.jpg

From Mikromasch http://www.spmtips.com/dgp/150/gp

Specialized C nanotube tipswww.xintek.com