PFFD Scaling Operation Tool (Shiny app) for microdroplet parallelisation

This record provides the source code for the PFFD Scaling Operation Tool, a Shiny application that recommends whole-chip operating flow rates (Qc, Qd; µL/min) for Lateral-PFFD and Vertical-PFFD devices based on the fitted scaling relations reported in Section 3.5 of the associated manuscript. The app evaluates the frequency model in SI units (Hz; Q in m³/s; d in m; µ in Pa·s; γ in N/m) with user-facing inputs/outputs in practical laboratory units (µL/min, µm, mPa·s, mN/m). Capillary number is computed as Ca_c = µ_c·U_c/γ with U_c = Q_c/(3A) and A = 50 µm × 100 µm (converted to m²), where Q_c is the whole-chip total flow and division by 3 is applied internally for per-channel velocity. The tool is intended as an operational guide within the scope of the fitted models and should not be interpreted as a guarantee of droplet quality or stability outside the experimental parameter space.