Abstract
Whispering-gallery mode (WGM) microdisk lasers show great potential for highly sensitive label-free detection in large-scale sensor arrays. However, when used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. Here we demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching. The technique relies on reference structures protected by locally dispensed passivation materials, and can be scaled to extended arrays of hundreds of devices. We prove the viability of the concept in a series of experiments, demonstrating robust and sensitive label-free detection over a wide range of constant or continuously varying temperatures. To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift.
Highlights
Whispering-gallery mode (WGM) resonators show great potential for label-free molecular detection [1,2,3], combining high sensitivity [4] and micrometer-scale footprint [2] with the potential for cost-efficient mass production [5] and highly multiplexed sensing [6]
When used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. We demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching
To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift
Summary
Whispering-gallery mode (WGM) resonators show great potential for label-free molecular detection [1,2,3], combining high sensitivity [4] and micrometer-scale footprint [2] with the potential for cost-efficient mass production [5] and highly multiplexed sensing [6]. While WGM-based biosensors are intended to measure surface attachment of biomolecules, the resonance position is sensitive to all effects that lead to a refractive-index change of the resonator core and of the surrounding comprising, e.g., photobleaching of the gain medium or temperature fluctuations. Another aspect that impairs the output signal of WGM-based biosensors is their sensitivity to temperature changes, caused by the thermo-optic effect of the core material and the physical expansion of the device.
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