Please cite this article in press as: P. Urwyler, et al., Surface patterned polymer micro-cantilever arrays for sensing, Sens. Actuators A: Phys. (2011), doi:10.1016/j.sna.2010.12.007 ARTICLE IN PRESS G Model SNA-7165; No. of Pages 7 Sensors and Actuators A xxx (2011) xxx–xxx Contents lists available at ScienceDirect Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna Surface patterned polymer micro-cantilever arrays for sensing Prabitha Urwyler a,b,∗ , Helmut Schift a , Jens Gobrecht a , Oskar Häfeli c , Mirco Altana d , Felice Battiston e , Bert Müller b a Paul Scherrer Institut, Laboratory for Micro- and Nanotechnology, 5232 Villigen PSI, Switzerland b University of Basel, Biomaterials Science Center, c/o University Hospital, 4031 Basel, Switzerland c University of Applied Sciences Northwestern Switzerland, Institute of Polymer Engineering, 5210 Windisch, Switzerland d University of Applied Sciences Northwestern Switzerland, Institute of Polymer Nanotechnology, 5210 Windisch, Switzerland e Concentris GmbH, Davidsbodenstrasse 63, 4012 Basel, Switzerland article info Article history: Received 29 September 2010 Received in revised form 7 December 2010 Accepted 9 December 2010 Available online xxx PACS: 81.16.Nd (nanolithography) 81.20.Hy (molding) 87.19.lt (sensory systems) 87.80.Ek (micromechanical techniques) 87.85.Rs (nanotechnology-applications) 87.85.dh (cells on a chip) Keywords: Micro-cantilever Polymer Sensor Injection molding Nanoimprint lithography Stamps Mold abstract Microinjection molding was employed to fabricate low-cost polymer cantilever arrays for sensor appli- cations. Cantilevers with micrometer dimensions and aspect ratios as large as 10 were successfully manufactured from polymers, including polypropylene and polyvinylidenfluoride. The cantilevers per- form similar to the established silicon cantilevers, with Q-factors in the range of 10–20. Static deflection of gold coated polymer cantilevers was characterized with heat cycling and self-assembled monolayer for- mation of mercaptohexanols. A hybrid mold concept allows easy modification of the surface topography, enabling customized mechanical properties of individual cantilevers. Combined with functionalization and surface patterning, the cantilever arrays are qualified for biomedical applications. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Micro-cantilevers (Cs), similar to those used in scanning force microscopes (SFM), have become increasingly popular as transduc- ers in chemical and biological sensors [1–8]. They convert physical, chemical, and biological stimuli into measurable signals. Various detection methods have been introduced to measure the bending of the Cs in the range of few nanometers with extremely high accuracy. A compelling feature of C sensors is that they operate in air, vacuum, or liquid environment [7]. Like many micro-machined ∗ Corresponding author at: Paul Scherrer Institut, Laboratory for Micro- and Nan- otechnology, ODRA 117, 5232 Villigen PSI, Switzerland. Tel.: +41 56 3102430. E-mail addresses: prabitha.urwyler@psi.ch (P. Urwyler), helmut.schift@psi.ch (H. Schift), jens.gobrecht@psi.ch (J. Gobrecht), oskar.haefeli@fhnw.ch (O. Häfeli), mirco.altana@fhnw.ch (M. Altana), battiston@concentris.ch (F. Battiston), bert.mueller@unibas.ch (B. Müller). devices, Cs are typically made from glass, silicon or other rigid materials. In the field of biomedicine, silicon-based Cs have to be cleaned or even sterilized for repetitive use. For single usage they are often too expensive. The fabrication is based upon single crystalline silicon wafers to be processed in cleanroom facilities. The high costs compromise many applications and calls for low- cost, disposable sensing elements. Polymer materials offer tailored physical and chemical properties to be combined with low-cost mass production. Therefore, compared to silicon-based Cs the polymeric Cs can exhibit better biocompatibility and much better adaptability of rapid prototyping along with mechanical proper- ties, which make them particularly sensitive [7]. Despite these advantages polymeric C arrays are not yet commercially avail- able. Polymer Cs can be prepared in a variety of ways, whereas the type of polymer often determines the fabrication method [7,9]. So far, polymer Cs were realized using photolithography. It is limited to the suitable materials and the Cs fabrication is rather expensive [10]. Molding of microcomponents from thermoplastic 0924-4247/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2010.12.007