The recent redefinition of the kilogram provides encouragement for widespread adoption of primary methods to realise the kilogram. To support this, NPL is building a "next generation" Kibble balance which, by eliminating the need for careful alignment of the coil and magnet, will be simpler in construction and operation than its predecessors. Work is currently concentrated on validating the operating principles of a prototype balance and ensuring its sensitivity and stability.

Kibble balance experiments have allowed the kilogram to be redefined in terms of the Planck constant. Now that the redefinition is in place, the Kibble balance will allow SI traceable mass (or force) to be realised at any value and at any location. A feasibility study for a novel, scalable electrostatic ‘µKibble balance’, based on the National Physical Laboratory (NPL) next-generation Kibble balance system is presented and its expected performance calculated. A µKibble will allowin-situ, dynamic, small-scale (< g) mass measurements without the current precision limitation caused by subdivision of the kilogram. The measurements will be traceable through electrical calibration rather than transferable mass standards. The instrument will have a wide range of applications in both industry and research.

NPL is building a next generation Kibble balance to encourage more widespread primary realisations of the kilogram following the expected revision of the SI in 2019. The new balance does not require careful alignment of the coil and magnet and is aimed at a relative standard uncertainty of 2×10 -8 . This paper describes progress on the development of the two technology demonstrator instruments which will guide the design of the next generation of Kibble balances at NPL.