Abstract: This document presents an original experimental proposal conceived by Moisés Corrêa da Silva (Lavras, MG, Brazil, June 2026) for measuring the magnetic vector potential A in a toroidal device with a topological knot winding — here called the double-entanglement caduceus toroid. The device combines two types of 90° crossings in series: external crossings at the outer waist and internal crossings at the inner edge of the toroid hole, creating two concentric rings of axial vector potential A_z not present in conventional toroidal coils. Numerical analysis shows a gain of 3.5x in the Aharonov-Bohm phase relative to a single external ring. The proposed measurement uses a Mach-Zehnder interferometer with one arm passing through the toroid hole, detecting the topological Aharonov-Bohm effect (B ≈ 0, A ≠ 0). The device is proposed as a laboratory analogue of the event horizon boundary layer described by the Ϡ (Sampi) Operator in the author's Unified Theory of Fields. A conventional toroidal coil serves as control. Falsification criterion is explicit. **Keywords:**vector potential, Aharonov-Bohm effect, toroidal coil, topological knot, caduceus winding, Mach-Zehnder interferometer, electromagnetic potential, Sampi operator, unified field theory, experimental proposal --- Resumo Este documento apresenta uma proposta experimental original de Moisés Corrêa da Silva para medição do potencial vetor A em toroide com enrolamento de nó topológico caduceus de duplo entrelaçamento. O dispositivo cria componente axial A_z com ganho de 3,5x sobre anel único. A medição usa interferômetro Mach-Zehnder. O dispositivo é proposto como análogo laboratorial do horizonte de eventos descrito pelo Operador Ϡ. **Palavras-chave:**potencial vetor, efeito Aharonov-Bohm, toroide, nó topológico, enrolamento caduceus, interferômetro Mach-Zehnder, Operador Sampi, teoria unificada dos campos, proposta experimental --- Pode copiar direto no Zenodo. O abstract em inglês vai no campo Description, keywords no campo Keywords.