All-silica microfluidic optical stretcher with acoustophoretic prefocusing

Giovanni Nava, Francesca Bragheri, Tie Yang, Paolo Minzioni, Roberto Osellame, Ilaria Cristiani, Kirstine Berg-Sørensen

Research output: Contribution to journalJournal articleResearchpeer-review


Acoustophoresis is a widely reported and used technique for microparticle manipulation and separation. In the study described here, acustophoresis is employed to prefocus the flow (i.e., focusing occurring upstream of the analysis region) in a microfluidic chip intended for optical trapping and stretching. The whole microchip is made of silica with optical waveguides integrated by femtosecond laser writing. The acoustic force is produced by driving an external piezoelectric ceramic attached underneath the microchip at the chip resonance frequency. Thanks to an efficient excitation of acoustic waves in both water and glass, acoustophoretic focusing is observed along the channel length (>40 mm) and it is successfully demonstrated both with polystyrene beads, swollen red blood cell, and cells from mouse fibroblast cellular lines (L929).
Original languageEnglish
JournalMicrofluidics and Nanofluidics
Issue number4
Pages (from-to)837-844
Publication statusPublished - 2015


  • Optical stretcher
  • Acoustic prefocusing
  • Femtosecond laser micromachining


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