High density optical pressure sensor foil based on arrays of crossing flexible waveguides Jeroen Missinne* a , Geert Van Steenberge a , Bram Van Hoe a , Erwin Bosman b , Christof Debaes c , Jürgen Van Erps c , Chunxiao Yan d , Eleonora Ferraris d , Peter Van Daele b , Jan Vanfleteren a , Hugo Thienpont c , Dominiek Reynaerts d . a Centre for Microsystems Technology, ELIS Dept., Ghent University-IMEC Technologiepark 914A, 9052 Zwijnaarde, Belgium; b Centre for Microsystems Technology, INTEC Dept., Ghent University-IMEC Technologiepark 914A, 9052 Zwijnaarde, Belgium; c Dept. of Applied Physics and Photonics (TONA-FirW), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium d Mechanical Dept., Katholieke Universiteit Leuven, Celestijnenlaan 300B, B-3001 Heverlee, Belgium. ABSTRACT To realize a high density matrix of pressure sensors, mainly electrical approaches are reported. The proposed high- density optical pressure sensor is based on a matrix of 2 stacked layers of crossing multimode waveguides. When pressure is applied on a crossing point, the distance between the waveguides from the upper and lower layer will decrease and power is transmitted between these waveguides. The sensor consists of polymer waveguides embedded in polydimethylsiloxane (PDMS) which is a very flexible material. Therefore, it is ideally suited to be applied on irregular or moving surfaces especially for applications which require covering small areas with high density pressure sensors. Keywords: array waveguide sensor, distributed pressure sensing, flexible waveguides, optical coupling, optical sensor foil, polymer waveguides. 1. INTRODUCTION Sensors are present everywhere in our daily life and provide interaction with and detailed information about our environment. A large amount of these sensors are based on electrical principles, but recently there has been a trend towards using optical sensors. These optical sensors have several advantages. They are insensitive to electromagnetic interference and potentially allow for higher sensitivities. Furthermore, the lower weight and the elimination of several electrical interconnections enhance the user comfort. Pressure sensing in particular is gaining importance in a number of domains such as tactile sensing for robotics and minimal invasive surgery. Several types of optical sensors are available and the majority is based on fibers [1], [2] or losses in waveguides [3], [4]. However, these sensors are generally limited to be used for lower densities while some applications require high-density pressure sensors. The proposed sensor principle relies on the changing coupling between 2 layers of crossing waveguides arranged in a dense matrix configuration. When applying an external force on a crossing point of 2 waveguides, light is coupled from one waveguide to another. This principle has a great potential for obtaining high-density, highly tunable and sensitive digital sensors. Furthermore, the waveguides are embedded in polydimethylsiloxane (PDMS) resulting in a very flexible sensor. *Jeroen.Missinne@UGent.be; phone +3292645512; fax +3292645374; www.cmst.be Micro-Optics 2010, edited by Hugo Thienpont, Peter Van Daele, Jürgen Mohr, Hans Zappe, Proc. of SPIE Vol. 7716, 77161G · © 2010 SPIE · CCC code: 0277-786X/10/$18 doi: 10.1117/12.854578 Proc. of SPIE Vol. 7716 77161G-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/20/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx