Fabrication of a paraffin actuator using hot embossing of polycarbonate

Lena Klintberg*, Malin Svedberg, Fredrik Nikolajeff, Greger Thornell

*Corresponding author for this work

Research output: Contribution to journalArticle

51 Citations (Scopus)


In this paper a fabrication process for integrating paraffin-actuated structures in polycarbonate is outlined. A paraffin-actuated membrane with a diameter of 2.5 mm, where the volume expansion of 10-15% associated with the solid-to-liquid phase transition of paraffin is utilized, has been fabricated and evaluated. Microstructures fabricated in silicon have via an electroplated nickel mould been replicated in polycarbonate by hot embossing and the resulting structures have been sealed by thermal bonding. The bonding strength was measured by a pressurizing test, and the polycarbonate surfaces were characterized with electron spectroscopy for chemical analysis (ESCA). It was found that the bond strength, increased when an oxygen plasma treatment was used prior to bonding. ESCA measurements showed a corresponding increase in oxygen content on the plasma treated surfaces. This procedure also improved the wetting properties. The contact angle between paraffin and polycarbonate decreased from 10° after embossing to about 5° after plasma treatment. The fabricated actuator had a total thickness of 1 mm and the membrane deflected about 140 μm when heating the actuator above the melting point of paraffin. Paraffin wax actuators are possible to integrate in plastic structures making them promising candidates in applications such as disposable microfluidic systems where inexpensive and robust valves and pumps are needed.

Original languageEnglish
Pages (from-to)307-316
Number of pages10
JournalSensors and Actuators, A: Physical
Issue number3
Publication statusPublished - 15 Feb 2003


  • Actuator
  • Bond strength
  • Contact angle
  • ESCA
  • Hot embossing
  • Paraffin
  • Plasma treatment
  • Polycarbonate
  • Polymer microfabrication
  • Thermal bonding

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