Localized heat processing of soft materials using a low-power microwave applicator

We report a microwave applicator operating at a few watts input power and used for selective heating of soft materials. The probe has a high efficiency in transmitting microwave radiation to well-localized regions without necessarily making contact with the irradiated medium. Our probe radiates microwave energy through a very narrow slot, with the width ranging from 500 μm down to 1 μm, microfabricated at the apex of a metal coated dielectric resonator. A temperature of ∼100°C is achieved in a spot size as small as 0.25×0.5 mm². Our microwave applicator may be useful for localized heating of biological tissues and polymer processing.