1. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Integrated Optical Microsensors Based On Porous Silicon Technology For Vapours And Liquids Identification L. Rotiroti, I. Rea, D. Alfieri, I. Rendina and L. De Stefano Institute for Microelectronic and Microsystem – Dept. of Naples, National Council of Research, Naples, Italy L. Moretti, F.G. Della Corte DIMET – Mediterranea University of Reggio Calabria, Reggio Calabria, Italy

2. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 …is a low-cost material and fabrication process; …has a large specific surface area (~ 200 m 2 /cm 3 ); …rapidly and effectively interacts with chemical species; …shows evident changes in several physical properties usable for sensing (reflectivity, photoluminescence, electrical conductivity, optical waveguiding...); …easy to integrate in hybrid systems (MEMS, MOEMS, TAS, Labo-on-Chip etc...);...compatible with microelectronic technologies; …its surface can be chemically modified to enhance analyte selectivity. The transducer element: PSi Si p+ type DBR # 1 DBR # 2 8.3 m

3. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 PSi Layer Carrier out Carrier in Analyte Pneumatic actuator A step further

4. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Silicon-glass anodic bonding Anodic Bonding is a bonding process of a silicon wafer to glass under the influence of high temperature and an externally applied electric field @ 200°C Electric Field 2500 V Planar Electrode Bonding time 5 min

5. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Flow Injection Analysis

6. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Experimental results-1 -chamber volume: 4 l -chamber volume: 4 l PSi layer thickness: 2 m -chamber volume: 12 l -chamber volume: 12 l PSi layer thickness: 6 m

7. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 VOC IsopropanolEthanolMethanol Response time 156 ms104 ms64 ms Recovery time 24 ms55 ms48 ms Experimental results-2 Comparison between response times due to different substances. All the measurements have been made in saturated atmosphere

8. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 The second device scheme The planar waveguide is realised by thermal oxidation of a SOI wafer, in a dry atmosphere at 1050 °C: a thin silicon oxide layer of 100 nm confines the light into a 3 μm thick crystalline silicon layer. The transduction element of this sensing device is fabricated by a two-step electrochemical etching process of a silicon wafer, p+ type, with a resistivity of 8-12 mΩcm, using an HF/EtOH (50:50) solution. The elements are joined together by AB technique.

9. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Experimental set-up and results An infrared laser ( =1550nm) is coupled into the SOI waveguide through an optical fiber. The trasmission beam is collected by another optical fiber and directed in a photodiode.

10. Ischia, 21-23 giugno 2006Riunione Annuale GE 2006 Thank you for your attention!