This data set contains the data collected during the FNS project Green Piezo (Grant no. 179064) in association with the recent publication entitled “Low-temperature processing of screen-printed piezoelectric KNbO3 with integration onto biodegradable paper substrates”. Associated Manuscript Abstract: "The development of fully solution-processed, biodegradable piezoelectrics is a critical step in the development of green electronics towards the worldwide reduction of harmful electronic waste. However, recent printing processes for piezoelectrics are hindered by the high sintering temperatures required for conventional perovskite fabrication techniques. Thus, a process was developed to manufacture lead-free printed piezoelectric devices at low temperatures to enable integration with eco-friendly substrates and electrodes. A printable ink was developed for screen printing potassium niobate (KNbO₃) piezoelectric layers in microns of thickness at a maximum processing temperature of 120 °C with high reproducibility. Characteristic parallel plate capacitor and cantilever devices were designed and manufactured to assess the quality of this ink and evaluate its physical, dielectric, and piezoelectric characteristics; including a comparison of behaviour between conventional silicon and biodegradable paper substrates. The printed layers were 10.7–11.2 μm thick, with acceptable surface roughness values in the range of 0.4–1.1 μm. The relative permittivity of the piezoelectric layer was 29.3. The poling parameters were optimised for the piezoelectric response, with an average longitudinal piezoelectric coefficient for samples printed on paper substrates measured as d_{33, eff, paper} = 13.57 ± 2.84 pC/N; the largest measured value was 18.37 pC/N on paper substrates. This approach to printable biodegradable piezoelectrics opens the way forward for fully solution-processed green piezoelectric devices." The data set consists of the following folders: Device design files Contains data associated with the design and fabrication of printed devices. Includes CAD designs of fabricated devices and py files of computational models Physical characterization data Contains data associated with characterizing the physical properties of the piezoelectric devices Includes particle size analysis data (SEM images of printed layers, collected dimensional data), Profilometry scans, Layer adhesion, ink density, and rheology data. Dielectric characterization data Contains data associated with characterizing the dielectric properties of the piezoelectric devices Includes py analysis script as well as raw data collected for capacitor devices of varying surface area and substrate material Piezoelectric characterization data Contains data associated with characterizing the piezoelectric properties of the devices Includes raw data collected from Berlincourt measurements of samples, matlab scripts for analysis of cantilever samples from Laser Doppler Vibrometry, and raw data collected for cantilever samples of device deflection from LDV measurements Please refer to the included readme files for a detailed description of the contents.