title: Joule heating monitoring in a microfluidic channel by observing the Brownian motion of an optically trapped microsphere.
abstract: Electric fields offer a variety of functionalities to Lab-on-a-Chip devices. The use of these fields often results in significant Joule heating, affecting the overall performance of the system. Precise knowledge of the temperature profile inside a microfluidic device is necessary to evaluate the implications of heat dissipation. This article demonstrates how an optically trapped microsphere can be used as a temperature probe to monitor Joule heating in these devices. The Brownian motion of the bead at room temperature is compared with the motion when power is dissipated in the system. This gives an estimate of the temperature increase at a specific location in a microfluidic channel. We demonstrate this method with solutions of different ionic strengths, and establish a precision of 0.9 K and an accuracy of 15%. Furthermore, it is demonstrated that transient heating processes can be monitored with this technique, albeit with a limited time resolution.
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Toon
authors.initials: T
authors.lastname: Brans
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Strubbe
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Caspar
authors.initials: C
authors.lastname: Schreuer
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: Vandewiele
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Kristiaan
authors.initials: K
authors.lastname: Neyts
authors.affiliation: Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.|Center for Nano and Biophotonics (NB-photonics), Ghent University, Ghent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Beunis
mesh_terms: D004867:Equipment Design; D006358:Hot Temperature; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D008863:Microspheres; D009038:Motion; D052898:Optical Tweezers
keywords: Brownian motion; Joule heating; Microfluidics; Optical tweezers; Temperature