On-Chip, Dynamic, and Cryogenic Temperature Monitoring via PDMS Micro-Bead Coatings

Polydimethylsiloxane (PDMS) microshells/beads coated onto an electrical current-carrying wire are demonstrated for on-chip, dynamic, cryogenic temperature measurement via monitoring optical whispering-gallery mode (WGM) frequency shifts. PDMS is found to be capable of supporting WGM resonance at cryogenic temperatures down to 95 K, limited by the present lab-built cryogenic working environment. The effect of the polymeric sensor diameter on temperature sensitivity is explored and discussed. The sensors are tested for their realtime temperature monitoring capabilities and accuracy in the cryogenic temperature regime of 95-140 K, and a comparison to a theoretical model, where the electrical resistivity of nichrome wire at cryogenic temperature is also experimentally determined, is examined. (C) 2016 Wiley Periodicals, Inc.