Charge–Capacitance Channel Decomposition Reveals Fabrication-Tolerant Design Windows for Disk Triboelectric Nanogenerators

Disk triboelectric nanogenerator (TENG) design pursues high structural figure of merit (FOMS), yet nominal peak designs often sit in regions with steep geometric gradients; under a controlled ±10% symmetric perturbation proxy, worst-case FOMS retention near the peak frontier falls to 2.7%. We decompose FOMS into a charge-transfer channel (Qsc,MACRS) and a capacitance channel (Csum−1), and train a multi-output surrogate with a physics consistency constraint on 1944 COMSOL simulations to jointly predict Qsc,MACRS, Csum−1, and FOMS across electrode-pair number, dielectric-thickness-to-radius ratio (h/R), air-gap-to-radius ratio (d/R), and dielectric constant. Evaluating 7776 design points reveals that 58.6% of the explored space is charge-dominant, 36.1% mixed, and 5.3% capacitance-dominant; raising dielectric constant shifts the mechanism toward capacitance-limited behavior, while a larger air gap reinforces charge-limited behavior. Mixed-regime windows tolerate the same perturbation proxy far better than peak-FOMS candidates, supplying candidate design windows for pre-fabrication screening within the validated simulation domain. The surrogate reaches pooled out-of-distribution FOMSRlog102=0.914 on 43 unseen structural and dielectric combinations. Delivered through an open-source Streamlit interface, the channel decomposition, mechanism mapping, and tolerance screening let designers identify the limiting mechanism and select candidate designs that are expected to tolerate geometric variation within the validated simulation domain, prior to fabrication.