Chemical Sensor Systems for Automotive Applications Udo Weimar - PowerPoint PPT Presentation

Chemical Sensor Systems for Automotive Applications Udo Weimar & Nicolae Barsan University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 2 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 3 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: why? • For n-type MOX one needs porous sensing layers for better performance • The presence of noble metal dopants/sensitizers is needed to decrease response time and operation temperature • One can obtain such layers by using powders, „dope“ them, make them into an ink and deposit them (screen-printing, drop coating, etc..) • Micromachined substrates allow for decreasing the power consumption and simplify packaging 4 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 5 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Microhotplate Institute of Microengineering (IMT), Samlab, Neuchâtel, Switzerland 6 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Microhotplate Institute of Microengineering (IMT), Samlab, Neuchâtel, Switzerland 7 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Microsensor: drop coated microhotplate 8 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Performance evaluation 100 200°C 30% r.h. 50% r.h. 250°C Sensor response G(CO)/G 0 300°C 70% r.h. 350°C 10 400°C 1 1 10 100 CO concentration (ppm) 9 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Simultaneous chemoresistive and thermal effects measurement of the sensor signal sensor type a) U ref R gai n + - U senso r sensitive Si N 3 4 membrane layer Au electrodes membrane sensor type a b dimensions thickness 0.5  m 0.85  m area 1x3 mm 2 1x1 mm 2 Pt heater silicon wafer b) +12 V U heat er U~ I heat er heater and measurement of sensor temperature 10 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Simultaneous chemoresistive and thermal effects 7 10 15 R sensor [  ] 30 100 60 10k 200 100 200 500 Pt doped / 50% r.h. 400 200 600 1000 1000 2000 2000 CO [ppm] CH 4 [ppm] C 2 H 5 OH [ppm] 1k 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 406 T sensor [°C] 404 402 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 time [min] 11 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Gas discrimination T heater = 400°C / Pt doped / 50% r.h. sensor signal R air / R gas CO CH 4 10 C 2 H 5 OH 1 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 -  T [°C] 12 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Application exploration a) sensor system CO, NO 2 13 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Test drive: prototype chemical sensor system 14 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: how? Test drive: comparison with EC 40 Electrochemical Cell signal 40 Microsensor signal 35 Log (sensor conductance) 35 CO concentration (ppm) 30 30 25 25 20 20 15 15 10 10 5 0 5 -500 0 500 1000150020002500300035004000 Time (seconds) 15 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 16 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: industrialization 17 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: industrialization Commercial microsensor electrodes heater sensing layer Si 3 N 4 – membrane 1 mm 0.45 mm Si 2 mm sensing layer R heater = 100 Ω R sensing ~ 100 Ω – 100M Ω 18 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: industrialization Application solution a) sensor system CO, NO 2 19 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: industrialization From prototype to commercial chemical sensor system 20 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 21 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: applications a) sensor system CO, NO 2 sensor system b) smoke, flatulence fast food 22 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: applications odor event test panel sensor data algorithm AQL test panel similarity AQL sensor module citation 23 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: applications 60 CO NO 2 50 Butanol 40 concentration [ppm] 30 20 10 0 0 50 100 150 200 250 300 350 400 450 500 time [min] -2 10 Pd3 Pt02 U -3 10 log conductivity [S] -4 10 -5 10 -6 10 0 50 100 150 200 250 300 350 400 450 500 time [min] 24 University of Tübingen Institute of Physical Chemistry

Thick films/microhotplates: applications AQL 5 Fast Food Manure 4 Flatulence Cigarette Smoke 3 AQL D Exhaust Gas 2 1 0 500 1000 1500 2000 2500 3000 time [s] 5 Enter freeway Start Eating Order Hamburger Eating finished Light Cigarette U-Turn Oil fogg Open bag Open/Close door Stop and Go Food in the car 4 Extinguish Cigarette Open/Close window Parking Continue Marker 3 2 1 0 500 1000 1500 2000 2500 3000 time[s] Fast Food Smell 25 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 26 University of Tübingen Institute of Physical Chemistry

Plastic sensors: why? • Decrease of cost by using processes compatible with large scale fabrication on foils (roll to roll, printed electronics) • Possibility to integrate on the same substrate additional functionalities (sensing and driving electronics, networking, etc) • Possibility to integrate them into a wide range of materials (textiles, packaging materials, etc ) • Possibility to address novel application fields • Low-cost smart sensing systems 27 University of Tübingen Institute of Physical Chemistry

Outline • Thick films/microhotplates combination – Why? – How? – Industrialization – Applications • Plastic sensors – Why? – How? – Current state of the art – Outlook 28 University of Tübingen Institute of Physical Chemistry

Plastic sensors: how? By combining of different sensing principles – Measurement of a wider range of gas concentrations – Higher selectivity – Differential measurements At no additional processing steps for the transducers Development partner: Institute of Microengineering (IMT), Samlab, Neuchâtel, Switzerland 29 University of Tübingen Institute of Physical Chemistry

Plastic sensors: how? A • Capacitive humidity and VOCs sensor [1] – Area: 1.4 x 1.4 mm 2 ε r2 A – Gap and finger width: 10 μ m   1  C r d , 2 0 d ε r1 – Ultra-low power consumption • Resistive metal oxide (MOX) gas sensor [2,3] – 100 μ m wide – Drop-coated Heater Gas sensitive layer – 10–28 mW (200-300°C) Electrodes Dielectric Pt temperature sensor: T   R  layer • 100 µm Substrate – Area: 1.4 x 1.2 mm 2 [1] A. Oprea, et al., Sensors and Actuators B, 140(2009)227-232. [2] D. Briand et al., Sensors and Actuators B, 130(2008)430-435. [3] J. Courbat et al., Proc. Transducers 2009, pp.584-587. Development partner: Institute of Microengineering (IMT), Samlab, Neuchâtel, Switzerland 30 University of Tübingen Institute of Physical Chemistry

Plastic sensors: how? • All processes on polyimide foil • Ti/Pt deposition (20/130 nm) and patterning • MOX layers – SnO 2 /Pd – WO 3 • Polymer layers – Cellulose acetate butyrate (CAB) – Polyetherurethane (PEUT) Technological platform: J. Courbat et al., Proc. of IEEE Sensors 2008 Conference, Lecce, Italy, pp.74-77. Development partner: Institute of Microengineering (IMT), Samlab, Neuchâtel, Switzerland 31 University of Tübingen Institute of Physical Chemistry