Micro Analytical Instruments - A System Approach. Jörg Müller Institut für Mikrosystemtechnik

Transcription

1 Micro Analytical Instruments - A System Approach Jörg Müller Institut für Mikrosystemtechnik Technische h Universität i Hamburg-Harburg H b

2 Outline Motivation Political Political Issues Design Principles Fabrication Processes Our Family of Micro Analysis Systems Electronic Hard- and Software Outlook

3 Standard Analysis Systems: well established technique high analysis power selectivity sensitivity multiple applications large systems Motivation significant energy and media consumption immobile significant analyte volume requirement of good vacuum (<10-2 Pa) rather expensive to buy and use hardly applicable in field and in-line-applications

4 Advantages of Micro Analytical Instruments operation at high pressure simple pumping system mobile small dimensions mass production by micro machining low power consumption easy to integrate high field strength at low voltage specially suited analysis principles complex signals with IC s in situ online measurement

5 Possible shortcomings of microsystems mangement of macro micro interface particle sensitive high capillary forces hard to clean low analyte consumption dead volumes on time supply of analyte selection of representative ti samples

6 Political obstacles conservative users (e.g. chemical industry) new price - man power - performance - relation direct comparison with sophisticated t lab equipment new, yet to be defined applications not appropriate macro micro interface critical overall promised performance too optimistic and too early small is not reliable small samples are not representative

7 Political pressures fast results (application and publication) performance comparable to lab equipment or better competition with system, developed in decades compatible to introduced d periphery identical application procedure. mostly only miniaturized subsystems are developed which are integrated into a macro system advantage of miniaturization is rather limited

8 Complex analytical micro systems may use other or new principles of operation may need application of different principles of operation will need adjusted macro-micro-interfaces will need compatible subsystem stem interfaces may offer new functions may be restricted in performance Only a full micro system approach guarantees optimum performance and full impact of miniaturization

9 applications fast In-situ-Monitoring of industrial processes mobile environmental analysis real-time analysis of exhaust gases Harsh-Environment -analysis Homeland Security space missions

10 Micro Analysis Systems Members of our micro system family Optical spectrometer Paramagnetic oxygen sensor Gas chromatograph (GC) Temperature conductance Detector (TCD) Mass flow controller (MFC) commercialized Analyte concentrator Planar integrated micro mass spectrometer Flame Ionisation Detector t FID Vacuum pump with Pirani pressure sensor gas injector IR-gas detectors Periphery: valves, channels, membranes etc.

11 System approach Design of complete system with compatible subsystems system simulation with multi physics and mathematical tools development of process steps development of appropriate materials mask design fabrication with standard MEMS technologies development of appropriate electronics development of adjusted software characterization of subsystems and systems

12 Family Identity: anodically bonded glas - silicon - glass sandwich Technologies: Photolithography Thin film deposition (CVD, PVD) Advanced d Silicon Etch (ASE, Bosch) process Wet chemical and plasma etching

13 Fabrication in MEMS-Technology

14 Optical spectrometer nm 450 nm 350 nm 550 nm 500 nm 600 nm 650 nm 350 nm 1E-3 1E-4 1E-5 1E µm

15 SiO2-SiON-waveguides on silicon SiO 2 -SiON-SiO < n < 2.0 Process development: LPCVD process: SiH 2 Cl 2 -O 2 - NH 3 T = 930 C PECVD process: Si-wafer thermal oxidation LPCVD-SiO 2 SiON deposition SiO 2 deposition SiH 4 - O 2 - N 2 T = 350 C photolithography plasma etching p g Optical loss: < db/cm 1986 ridge waveguide

16 eff ficiency 0,6 05 0,5 0,4 0,3 0,2 0, wavelength / nm Spectral grating efficiency inten nsity & wavelength / nm Spectrum of a high pressure Hg-vapour bulb 16

17 Paramagnetic oxygen sensor

18 µ Gas Chromatograph GC-column integrated TCDs injector 10 C 1 8 [mv] TC CD bridge signal C 2 C 3 GC2001 SNG C 4 C 5 Mass flow sensor Time [sec]

19

20 2 Column µ-gc 160 mm 100mm

21 Micro mass spectrometer (PIMMS) small dimensions reduced vacuum requirements (1Pa) reduced energy consumption small analyte volume (pl) fast analysis a s (< 1s) mobile system low cost mass production field and in-line spectroscopy available

22 small dimensions Objectives high frequencies low capacitive loading (low power) low media consumption (gas, electrical power, analyte) chemically stable materials combination of electrically conductive and isolating materials established process technology reproducible batch fabrication on wafer scale use of standard electronics (voltages, currents, frequencies)

23 PIMMS Planar-Integrated Micro Mass Spectrometer Dimensions 7x10mm²

24 Realization Batch process for 100 devices on a 4 wafer Pressure in plasma and p ionization chamber installed via capillaries dimensions

25 Electron Source Dark-space reduction by variation of area ratio of electrodes previous new Electron extraction increased 40 from 2.5µA to ~37µA 30 µwave power ~200mW 20 Current [μa A] Chamber Pressure [Pa]

26 Synchronous Ion Shield Mass Separator path path-time-field-diagram electrical field orthogonal to ion flight path = field free = strong field only ions in field free region pass Ion cu urrent time mass

27 Redesigns Signal Generator for SIS four signals rise time < 1ns frequency range DC-50 MHz resolution < 0.1 Hz pulse height 5V linear scan of frequency or mass standard ICs used

28 Ion current amplifier High input impedance current to voltage converter Rise time < 3ms low noise < 0,2pA Directly adjacing PIMMS

29 Measurement set-up

30 Electronic boards µcontroller Current measurement I/O-interface spark ignition high voltage ± 230V voltage supply power connect Expected to be reduced to 3 to 5 ASICs

31 Software manual control of system components: HV-, RF-, DC-sources, SIS generator, etc. display of operating parameters and measurand automated booting of optimum operating parameters storage and booting of operating parameters recording, display, storage, and booting of spectra control of periphery: p pumps, p flow controllers, etc.

32 Software data recording linear in frequeny linear in mass display of spectra vs frequency vs mass Coice of resolution and measuring cycle time data storage individual multiple storage of comments with respect to indiviudal measurements Data format for storage: XML (EXtensible Markup Language)

33 Measurements

34 Micro Channel Plate Integration of a Micro Channel Plate (MCP) amplification >1.000 supply voltage <1,2 kv Pore- diameter 10µm aspect ratio 1:40 (Pore length 400µm)

35 Hybrid Integration of Micro Channel Plate

36 results Time for measurement: 4s Mass resolution: 32 (half peak width) air: N 2 28u 78% O 2 32u 21% Ar 40u 0,9% CO 2 44u 0,04% Xenon as plasma gas: Xe 131u Sensitivity ~ 100 ppm

37 results Variation of SIS-signal 2eU m = ( ) 2 d f d = 800µmµ d = 1600µm

38 results spectrum of Helium: width of finger electrodes increase by factor 2 Mass range shifted by factor 4 i.e. from 12u to 1200u to 3u to 300u

39 hydrogen

40 Methane resolution (FWHM) : 32 range: 0,5 m/z 50 m/z noise after averaging: 0,02 pa

41 Summary PIMMS MEMS approach allows for: cost efficient mass production portability new fields of application reduced requirements for base pressure may allows to use micro pumps resolution in the range of 3 bis >200 amu demonstrated sensitivity better than per mille mass resolution > 35 time response of electronics τ = 3 ms spectrum from 3 to 150 amu recorded in 4s

42 FID Quantitative measurement of organic compounds Measurement principle: Hydrogen flame ionization Electrical field (200 to 600V) generates ion current Applications: Gas Chromatography (GC) Total Hydrocarbon Analysis (THA) Disadvantages: Hydrogen High synthetic air consumption High voltage Ignition Anode Cathode Flame Air ~ 300 sccm H 2 ~ 30 sccm 2 Sample gas

43 cc-µfid Design Advantages: Encapsulated flame pure oxygen instead of synthetic air Thermally isolating glass substrates Stable counter-current flame with stagnation point: Minimal heat loss due to forced convection Long residence time of the sample in the flame Ion current saturation at low voltages

44 cc-µfid Design H2 + sample inlet H2 + sample nozzle Ignition Bond pad Si electrode Temp. sensor O2 inlet O2 nozzle Cr Guard SiO2 isolation Pt measurementt electrode l t d

45 cc-µfid Ignition

46 cc-µfid Temperature sensing Temperature at H 2 = O 2 = 7.5 ml/min measures 210 C

47 cc-µfid I vs. U H 2 = O 2 = ml/min, CH 4 in N 2.0ml/min Saturation below 10V for small concentrations

48 cc-µfid Performance ml/min H 2, 1%CH 4 in 2.0ml/min N 2 O 2 brightness, sensitivity

49 cc-µfid Performance ml/min H 2, 1%CH 4 in 2.0ml/min N 2 O 2 brightness, sensitivity

50 cc-µfid Performance H 2 = 7.5ml/min, 1%CH 4 in N 2 = 2.0ml/min H 2 =O 2 = 7.5ml/min, N 2 = 2.0ml/min FID type H 2 (ml/min) O 2 (ml/min) Sensitivity (mc/gc) P-P Noise (pa) MDL (gc/s) Planar cc-µfid cc-fid FID conv AIR

51 Micro pump concept objectives: pump power > 1 ml/min starting from normal pressure base pressure: < 1 Pa electrically driven no additional media necessary energy and volume requirements similar to MEMS vapour jet pump

52 Micro vapour jet pump liquid vapourized by heater (platinum) nozzles generate vapour jet vapour condenses fluid assembles in reservoir porous membrane delivers liquid to heater ( sponge -principle) [channels connect reservoir to membrane]

53 Micro vapour jet pump liquid vapourized by heater (platinum) nozzles generate vapour jet vapour condenses fluid assembles in reservoir porous membrane delivers liquid to heater ( sponge -principle) [channels connect reservoir to membrane] Pirani pressure sensor

54 MEMS Vapor-Jet Vacuum Pump Ultimate Pre essure / mba ar μm 90 μm 125 μmμ Supply Pressure / bar p min = 500 mbar put / ml/min Through (working fluid: water vapor) Supply pressure e / bar

55 Funded by

56 Thank You for Thank You for your attention