Estimation from Cantilever Geometry

This method for Spring Constant Calibration is quick, but suffers from uncertainty because, typically, the specific cantilever geometry is not measured. Instead, a representative of the appropriate family of cantilevers is used, although exact geometric measurements may vary in production.

Each cantilever family is distinguished by a tip factor, b, in Newton-seconds³/meter. The spring constant for a cantilever in the family is derived from the measured resonant frequency, f in seconds^–1, of the free cantilever in air using the equation:

The assumptions of this relation are that cantilevers within a family agree in material properties and in geometry, with the exception of cantilever thickness, which varies from wafer to wafer. Typical average tip factor values by cantilever class are provided in Table 1:

Table 1: Typical Tip Factor Values

	Identify your probe type.
	Use the Cantilever Tune functionality to measure its resonant frequency.
	Use the formula above to calculate the spring constant.

See the Bruker probes website for more information about available probes.

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