ISO 28600:2011 – Surface Chemical Analysis — Data Transfer Format for Scanning-Probe Microscopy

Introduction to SPM Data Standardization

ISO 28600:2011 addresses a fundamental challenge in scanning-probe microscopy (SPM): the lack of interoperability between data formats from different instrument manufacturers. Before this standard, SPM data generated on a Bruker/Digital Instruments system could not be read by Asylum Research or Park Systems software without proprietary format conversion. ISO 28600 establishes a vendor-neutral, XML-based data transfer format that preserves all essential measurement metadata, image data, and spectroscopy information.

File Format Structure and Data Elements

The ISO 28600 format is based on Hierarchical Data Format 5 (HDF5) as the container, with an XML metadata block describing the measurement context. The structure includes four mandatory groups: /Measurement (instrument settings, scan parameters, environment), /ImageData (2D or 3D arrays of topographic and auxiliary channels), /Spectroscopy (force-distance curves, current-voltage spectra), and /ProcessingHistory (filtering, flattening, and analysis steps applied). All spatial coordinates use SI units (meters with appropriate prefixes).

Calibration and Uncertainty Requirements

ISO 28600 mandates that all quantitative data include calibration traceability information. For lateral (x,y) calibration, the standard requires reporting of calibration grating pitch (nm), calibration date, and calibration uncertainty (nm). For vertical (z) calibration, the piezoelectric sensor linearity data and calibration curve must be included. The format supports storage of multiple calibration files and allows the data user to apply alternative calibrations if the original is found to be inaccurate.

Engineering Applications and Data Sharing Benefits

The adoption of ISO 28600 has significant practical benefits in industrial SPM laboratories. Multi-site organizations can share data between facilities without format conversion. Academic collaborations benefit from the ability to apply different analysis software to the same dataset. For quality control applications, the standardized format enables automated analysis pipelines that process SPM data from multiple instruments using consistent algorithms, reducing inter-instrument variability in reported metrics such as surface roughness (Ra, Rq, Rz) and particle dimensions.

Metadata Requirements for Reproducible Measurements

A key contribution of ISO 28600 is the comprehensive metadata schema that accompanies the raw SPM data, enabling full traceability and reproducibility of measurements. The /Measurement group must include: instrument manufacturer and model, software version, probe type and nominal parameters (resonant frequency, spring constant, tip radius), scan mode (contact, tapping, non-contact), scan size in meters (precise to nanometer resolution), pixel count, scan rate in Hz, setpoint in volts, feedback gains (proportional and integral), environmental conditions including temperature (K), relative humidity (%), and any vibration isolation specifications. For quantitative measurements (step height, surface roughness, critical dimensions), the calibration traceability data must include: calibration standard identification (e.g., “NIST traceable 180 nm step height standard, S/N 12345”), calibration date, calibration uncertainty at 95% confidence, and the date of last calibration verification. This level of metadata detail is essential for forensic examination of SPM data in quality control and research contexts, where questions about measurement validity often arise months or years after the original data acquisition.