The complex Helmholtz operator is a ubiquitous operator that arises in multiple fields, ranging from thermal conductivity measurement to electrochemical impedance spectroscopy. Motivated by the absence of analytical tools used to solve the complex Helmholtz equation in non-separable domains, we present a new transform approach to solve the complex Helmholtz equation in convex polygonal domains. We use the approach to obtain new analytical solutions related to electrochemical impedance spectroscopy, and the 3\omega method. [Joint work with Prof. Darren Crowdy]