advances in miniature spectrometer and sensor … · ultra-compact chip spectrometer mir/tir fpi uv...

Advances in miniaturespectrometer and sensordevelopment

Jouko Malinen

VTT Technical Research Centre of Finland

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Co-authors

Dr. Anna Rissanen MEMS FPI technoloyDr. Heikki Saari Piezo-actuated FPI and hyperspectral

technologyDr. Mikko Karppinen Spectrometer integrationDr. Pentti Karioja R2R printed sensorsDr. Timo Aalto Silicon photonicsMr. Kari Tukkiniemi ASIC design

SPIE Next Generation Spectroscopic Technologies 2014




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Outline

Why miniatureFabry-Perot tunable filterMEMS spectral enginesSpectrometer integrationPiezo-actuated FPIEmerging sensor developments





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Motivation for miniaturization

• Miniaturizing spectrometers into hand held-mobile-connected sensorscreates opportunity for novel applications:

Cost critical process on-line measurementsEnvironmental sensing (Internet of Things)Gas sensingHealth and wellness, diagnostics

From benchtop to handheld





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Introduction – Fabry Perot interferometer


Basic equation for transmitted wavelengths:= 2d/m

Passband = 430 nm




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PIEZO-ACTUATED

Large aperture sizes, ~20 mmAccurate gap control through integratedcapacitance measurement

Easily customizedFor low to medium annual volumes

MEMS

Optical apertures up to ~2 mmSuperior mirror flatnessInsensitive to vibrations or positioningLow operational voltagesFor medium to high annual volumes

The two filter platforms - summary


MEMS spectral engines




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MEMS spectrometer development andcommercialization at VTT

20 year development effort, 15M€+ investment, 100 man yearsMEMS-FPI solutions covering UV-VIS-NIR-IR-TIR, 350nm – 12 µmSupporting patent portfolioPartners: Vaisala, VTT Memsfab, Spectral Engines …


1997 - 2003

VaisalaCarboCap

2009

Fuel qualitysensorEthylene

sensor forESA

20122006

GasSensor

2014

ImagerPen

spectrometerImaging

platform dvlpt

memsNIR

2013




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MEMS FPI process platforms & wavelengths

NIR/MIR FPIUV/visible FPI

Ultra-compact chip spectrometer

MIR/TIR FPI

UV200 – 350 nm

Visible350 – 800 nm

Low NIR0.8 – 1.1µm

Near IR1,1 – 2,5 µm

Mid IR3 – 7 µm

Thermal IR7 – 12 µm

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Moisture in paper (0.1, 3.5 and 10.1%)

Wavelength ranges1.3 - 1.7 µm1.6 - 2.0 µm1.7 - 2.2 µm

Resolution(% of wavelength)1 0.7-1.4 %

Wavelength settling time < 0.8 ms

SNR (typical) 3000

Power consumption < 1 W

Optical interface SMA 905

Input fiber core diameter Max. 400 µm diam.

Numerical aperture 0.22

Wavelength stability < 0.1 nm / C

Dynamic range > 15 bits

Size 50 x 35 x 20 mm3

Weight < 50 g

Operating temperature range +10..+35 C

memsNIR prototype


NIR spectrometer engine




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MEMS hydrocarbon gas sensor

Main characteristicsWavelength range 3000-3500 nm

Spectral resolution 50-60 nm

Optical path length 17 mm

Spectrum acquisitiontime

2 s (10 spectralpoints)

Power consumption(continuous mode) < 2 W

Size 77 x 38 x25 mm

Weight 95 g

Mannila R., Tuohiniemi , M., Mäkynen, J., Näkki, I., Antila, J., "Hydrocarbon gas detection withmicroelectromechanical Fabry-Perot interferometer ", Proc. SPIE 8726, 872608 (2013).





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Wavelength range from 7.5 µm to 9.5 µmControl voltage from 0-30VFWHM of 140nmAperture size 1.2 mm/4 layers of polysilicon-air-polysilicon

Mirrorstructure

Thermal IR MEMS Fabry-PerotInterferometer

MEMS FPI cross sectionTuohiniemi, M., Blomberg, M., Akujärvi, A., Antila, J., Saari, H., “Optical transmission performance of a surface-micromachinedFabry-Pérot interferometer for thermal infrared” J. Micromech. Microeng. Vol. 22(11), 115004, (2012).

Tuohiniemi, M., Näsilä, A., Mäkynen, J., “Characterization of the tuning performance of a micro-machined Fabry-Pérotinterferometer for thermal infrared”, J. Micromech. Microeng. Vol. 23 (7), 075011, (2013).

MEMS FPI characterization





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Spectrometer performanceat sensor price point

Spin-off starting from VTT

www.spectralengines.comSPIE Next Generation Spectroscopic Technologies 2014




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Spectrometer integration




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Competences and challenges for miniaturization

High-precisionalignment(passive or active;e.g. fiber pigtailing)

Encapsulation(hermetic sealing,windows)

3D integration andpackaging(electronics,bare die mountinggas/liquid channels,…)

Thermal management(CTE matching,temperature control,minimized dissipation)


Electronicsintegration(performance, EMIissues)

Silicon photonics(propagation losses,optical throughput,polarization)




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System-on-package: mid-IR gas analyzer


10 cm

Test setup

Protosensor head




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Piezo-actuated FPI -spectrometers andhyperspectral cameras




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Piezo-FPI platform

Piezo-actuator tuneable FPI assembled from MEMS-based reflectorsSmall- to medium volume productionEasy customization and fast device prototypingcompared to MEMSLarge optical aperture provides excellent sensitivityLarge tuning range with single elementRobust construction (tested for space requirements)Wavelengths from UV to thermal IR

UV200 – 350 nm

Visible350 – 800 nm

Low NIR0.8 – 1.1µm

Near IR1,1 – 2,5 µm

Mid IR3 – 7 µm

Thermal IR7 – 12 µm

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VIS-VNIR hyperspectral camera

Light-weight (~0.5 kg): can beoperated with low-cost UAVsWavelength range 500 - 900 nmWavelength resolution 10 nmCMOS image sensor 1 – 5 Mpix

Publications:Saari, H et al, “Unmanned Aerial Vehicle(UAV) operated spectral camera system forforest and agriculture applications”, Proc.SPIE 8174 (2011).

Smallbiomass

Largebiomass

Commerciallyavailable:

www.rikola.fi




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VIS-VNIR hyperspectral camera in medicalapplication studies

VTT’s camera can detect skin cancer within secondsEasy-to-use hand held instrumentFast screening and early detection of skin cancerApplication being studied at the University of Jyväskylä

Wavelength range:500-900 nm

Wavelength resolution:Ca. 10-30 nm

Spatial resolution:2 Mpix

Development status:• 1st generation

prototype done• Application studies

ongoing

Neittaanmäki-Perttu, N., Grönroos, M., Tani, T., Pölönen, I., Ranki, A., Saksela, O.and Snellman, E., “Detecting Field Cancerization using Hyperspectral ImagingSystem”, accepted for publication in Lasers in Surgery & Medicine Journal in June2013.





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Wavelength ranges of Piezo-FPIand image sensors


Available, dielectric mirrors

Available, metallic mirrors

Customizable, dielectric mirrors

Wavelength (µm)

1 10.2 .3 .4 .6 .8 2 3 4 6 8 11 12 141 10

Wavelength (µm)

1 10.2 .3 .4 .6 .8 2 3 4 6 8 11 12 141 10

Metallic FPImirrors

Dielectric FPImirrors

Dielectric FPImirrors

CMOS&CCD

InGaAsExt-InGaAs

InSbMCT




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Stand-off Raman spectroscopy at FOI withUV-FPI

Precise selection of Raman shiftsin combination with high out-of-band blockingWorks in the UV range where nocomparable filtering systems arecommercially availableCompact, high resolution (~0.2 nm@ FWHM) UV-FPIModule operation stable undervarying environmental conditions

Glimtoft, M., Bååth, P., Östmark , H., Saari, H., Mäkynen, J., Näsilä, A.,“Towards eye-safe standoff Raman imaging systems”, SPIE Proceedings 9072,(2014).





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Large aperture piezo-FPI gas sensors

Separately assembled Mid-IR FPI tunable filter platforms forMulti-gas measurementsCorrelation spectroscopy

Large apertures provide high optical throughputApplication testing with an industrial gas analysis systemQuantitative multi-gas analysis possible





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Single-Band Tunable FPI Filter Platform

Replacement for filter wheelBragg mirrors fabricated onsilicon wafersCapacitive air gapmeasurement and off-the-shelf piezos for actuationDedicated assembly andcalibration procedureTunability: 4-5 µmSpectral resolution (wideband due to applicationneed): ~70 nm (FWHM)

Air gap

Piezoactuation

Electrodes

n=1..2air gap=2..3 µm





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Correlation Spectroscopy FPI Platform

Correlation spectroscopy forhigh sensitivityAir gap in millimeters (highdiffraction order)Spacers provide small gap foraccurate capacitivemeasurementTransmission pattern mimicsabsorption of COTunability for correlation andanti-correlation with CO

Air gap

Spacers

Piezoactuation

Electrodes

n=~550air gap=~1.2 mm





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Emerging sensordevelopments




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Printed and Hybrid Functionalities research at VTTResearch Focus

From printed components to printed and hybrid systemsSolutions

Technology (material development and tuning, process planning and design,device and systems designs and modelling) and business development services,examples:

Printed solar cells, lighting solutions (ILEDs, OLEDs), printed transistors,printed sensors and indicators, printed power sources, nanoparticles andfunctional inks

Scaling up services using printing and hybrid pilot lines

Benefit to CustomersNew thin flexible product concepts made possibleHelp in finding new business opportunities availableLow risk for scaling up production





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Nanoimprint lithography NIL


UV nanoimprint process Roll to roll UV-imprinting process

Sheet level R2R UV-replication

Current status 3 … 5 1.5 … 2

R&D status 4 … 7 2 … 3

Best results in the field 6 … 10 3

Aspect ratios for differentprocesses at present day

29

R2R waveguide sensors

Sensor roll Sensor chip Sensor waveguide

Sensor roll length is some hundreds of metersSensor chip dimensions are in centimeters mostly due to robust samplehandling-> one roll can contain tens of thousands of sensor chipsTypical waveguide width is 1…3 µmSensor elements are functionalized/passivated in post-process

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R2R SERS sensor chip development inPhotosens consortium project

Nanoimprinted roll of substrateshowing continuous SERS array

Nanoimprinted roll of substrateshowing and cut out 96 wellplate (gold coated)


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Enabling technology: Silicon photonics

Photonic integrated circuits on SOI wafersVTT has developed a unique µm-scale SOI waveguide platformDense integration and low-cost volume productionLow propagation losses (0.1 dB/cm)Small polarisation dependencySingle-mode operation over an ultra-wide wavelength range




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Microspectrometers with silicon photonics ?

Emerging technology for microspectrometers in the futureMultiple wavelength filters in a single circuitWideband & narrowband filtering combinedFilter tunability, switching and modulationLight sources and detectors can be hybridintegrated on SOI chips


Thank you for your attention !

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advances in miniature spectrometer and sensor … · ultra-compact chip spectrometer mir/tir fpi uv...

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