Double Layer Potential Electric Impedance Tomography Helmholtz Equation Shift of scattering resonances Single Layer Potential Absorption Enhancement Asymptotic Expansion Background Solution Bernhard Riemann Bio-sensing Boundary Measurement Boundary perturbations Complete Asymptotic Expansion Conductivity Distribution Consciousness Critical Radius Diffraction Limit Dirichlet Boundary Condition Elastic Inclusion Elastic cloaking Elastic crack Elastic scattering Exceptional scattering resonances Expansion formula Exterior Domain Fredholm Type Generalized polarization tensors Green Function Harmonic Conjugate Harmonic Function