Microweights

Microweights are miniature calibration masses used for precision metrology at micro- to milligram scales. They are designed to calibrate and characterize micro-scale weighing devices such as microbalances, quartz crystal microbalances, AFM cantilevers, and MEMS force sensors. The term covers a range of discrete masses and shot-type weights intended to provide traceable mass references for small-scale instrumentation.

Manufacture and calibration: microweights are manufactured from stable, dense materials with low thermal expansion, such as tungsten alloys, platinum, or nickel-iron, and often finished with a corrosion-resistant surface. Each weight is individually calibrated against a national or international standard mass, and delivered with a documentation that lists the nominal mass, the uncertainty, surface geometry, and environmental coefficients. Weights are typically enclosed in protective packaging and supplied with traceability certificates.

Applications and measurement considerations: in practice, microweights are used to calibrate microbalances and micro-scale sensors by placing the weight on the sensor and recording the output. Readings must account for buoyancy effects, air currents, and temperature drift. Handling requires specialized tools to avoid contamination or mass exchange, and weights should be used within specified environmental conditions to maintain accuracy.

Limitations and variations: while microweights enable precise calibration, their small mass makes them sensitive to surface contamination and electrostatic effects. Some producers offer standardized sets covering multiple masses and tolerances, while others provide custom weights for specific instruments. The concept of microweights overlaps with calibration weights in metrology but is specialized for micro-scale devices.