Tunable liquid lens for three-photon excitation microscopy

Samuel D Gilinsky; Diane N Jung; Greg L Futia; Mo Zohrabi; Tarah A Welton; Omkar D Supekar; Emily A Gibson; Diego Restrepo; Victor M Bright; Juliet T Gopinath

doi:10.1364/BOE.516956

Tunable liquid lens for three-photon excitation microscopy

Biomed Opt Express. 2024 Apr 24;15(5):3285-3300. doi: 10.1364/BOE.516956. eCollection 2024 May 1.

Authors

Affiliations

¹ Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA.
² Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA.
³ Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA.
⁴ Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA.
⁵ Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA.
⁶ Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, USA.

Abstract

We demonstrate a novel electrowetting liquid combination using a room temperature ionic liquid (RTIL) and a nonpolar liquid, 1-phenyl-1-cyclohexene (PCH) suitable for focus-tunable 3-photon microscopy. We show that both liquids have over 90% transmission at 1300 nm over a 1.1 mm pathlength and an index of refraction contrast of 0.123. A lens using these liquids can be tuned from a contact angle of 133 to 48° with applied voltages of 0 and 60 V, respectively. Finally, a three-photon imaging system including an RTIL electrowetting lens was used to image a mouse brain slice. Axial scans taken with an electrowetting lens show excellent agreement with images acquired using a mechanically scanned objective.