This paper describes the use of Metal RubberTM, which is an electrically-conductive, low modulus, highly-flexible, and optically transparent free-standing or conformal coating nanocomposite material that is fabricated via Electrostatic Self-Assembly (ESA), as a polymer MEMS sensor for actuator materials. ESA is an environmentally-friendly layer-by-layer fabrication technique in which Metal RubberTM can be tailor designed at the molecular level to function as a sensor and/or electrode for active polymer devices. With its controllable and tailorable properties (such as mechanical modulus [from less than 0.1 MPa to greater than 500 MPa], electrical conductivity, sensitivity to flex and strain (tension and compression), thickness, transmission, glass transition, and more), Metal RubberTM exhibits massive improvements over traditional stiff electrodes and sensors (with bulky/heavy wire components) that physically constrain the actuator device motion and thus limit productivity. Metal RubberTM shows exceptional potential for use as flexible sensors, electrodes, and interconnect components for many active polymer applications. One example of such is NanoSonic's Metal RubberTM-Polymer MEMS (MRTM-PMEMS) nanocluster-based corrosion sensor for aircraft coatings that was developed for an Air Force SBIR program. MRTM-PMEMS was tailored via ESA for use as an in-situ sensor of chemical modifications and the breakdown of surface coatings via micro-strain measurements.