Selective deposition of dielectric thin films on an optofluidic biosensor provides the means for low loss in hollow-core waveguides and increased solid- to hollow-core coupling. Polymethylglutarimide (PMGI) is used over nonplanar topographies to provide liftoff patterning of dielectric films deposited at temperatures up to 250°C . This fabrication method provides throughput improvement in devices with hollow-cores longer than 2 mm.