There is an increasing demand for sensitive, selective, fast and portable detectors for trace components in gases and liquids, e.g. due to increasing concerns about atmospheric pollutants, and a need for improved medical screening capabilities for early detection of diseases and drug abuse. In that context, the project IrSens aims at building a versatile platform based on optical spectroscopy in the near and midinfrared range. Indeed, techniques based on optical absorption offer the possibility to realize a non-invasive and highly sensitive detection platform. It allows to probe the vibrational frequencies of the targeted molecules - most of which are located in the near and mid-infrared range, and to obtain an unambiguous signature of the investigated gas or liquid. The idea is to create a photonic sensor platform with high performance and reliability which will leverage on the new source, detector and interaction cell technologies to create a new sensor element with vastly improved performance and lowered cost. These improvements will be demonstrated further by the incorporation into two pilot applications, the first one aiming at the demonstration of sensing in the gas phase, the second one in the liquid phase.

1. RTD Project IRSENS
Integrated sensing platform for gases and
liquids in the near and mid-infrared range
Y. Bonetti, J. Faist
ETH Zurich
Plenary meeting – Bern – May 12, 2011
IrSens

2. Project Synopsis: Needs
gas
fluid
Medicine
(Diagnosis, Monitoring)
Sensing of small
molecules (CO,
Environment
(Pollution, Modelling) CO2, NxOy, ...)
Sensitive Portable,
Selective Low Power
Infrared Spectroscopy Semiconductor System
IrSens

3. Approach: optical sensing
Laser detector
N O
IrSens

4. holistic approach
Gas
QCL, QCD,
Electronics
VCSEL SiGe CMOS
Liquid Yes/No
%
IrSens

5. Pilot/focus applications
Gas: CO2 isotope ratios, e.g for plant
respiration monitoring – environment
Liquid: Cocaine in saliva detection
(presence yes/no) – traffic security
Platform: develop tools and techniques
Collaboration with industry started
IrSens

6. Measurements in Gases
IrSens

7. Schematic of the VCSEL gas-
sensing demonstrator (TDLS)
Collaboration with an industry
in collaboration with IR Microsystems / Leister
IrSens

8. Cylindrical Multipath Gas Cell
20*20*5 cm3
IrSens

9. Benchmarking
Instrumentation benchmarked with different techniques:
- Direct Absorption (DA)
- Wavelength Modulation (WM) - Prototype cell
- PhotoAcoustics (PA) - wrong QC laser!
Technique DA WM PA Picarro (CRDS
(NanoTera) (NanoTera) (NanoTera) reference)
1s precision (‰) 0.47 0.75 58.8 0.67
best precision (‰) 0.06 (200s) 0.05 (3000s) 0.65 (8000s) 0.1 (300s)
see poster!
IrSens

10. Also software!!
full hardware control
data acquisition and processing:
- real-time fitting module based
- on Hitran database
measurement automation
IrSens

11. Measurements in Liquids
IrSens

12. Benchmarking with ATR-
Spectroscopy
best spectral
range for
Cocaine in H2O
around 1730/cm
→ sources and
detector design
IrSens

13. QCL 1721 cm-1 measurements
●
Strong increase in signal during drying, as expected
●
Limit of detection around 20 µg/ml
see poster!
IrSens

14. Microfluidic Cell
Source
Detector
Waveguide
Inlets and
Mixer
Outlet
IrSens

15. Transmission through
waveguide at 6µm see poster!
Waveguide
QCL
ZnSe lens
Detector total transmission
through 9mm*5µm
waveguide: 4 %
IMT
Institut de microtechnique IrSens

16. Microfluidic Sample Preparation
for IR-Detection see poster!
Problem µ-flu. requirements Answer
low-cost materials and rapid prototyping of
disposable chips
fabrication process UV-glue
transfer to IR-transparent
mid-IR absorption of water liquid-liquid extraction
solvent
IR-transp. organic solvents chemical compatibility of
compatibility tests
used for extraction chip to solvents
aqueous and organic solvents handling of multiphase adjusting wetting
on chip flows behavior of UV-glue
materials with high
absorption of analytes absorption tests
recovery rate
improvement of liquid- droplet generation &
fast sample preparation
liquid extraction separation
IMT
Institut de microtechnique IrSens

17. Microfluidic Sample Preparation
for IR-Detection
fluid mixing parameters need good control
IMT
Institut de microtechnique IrSens

18. Support workpackages:
Sources:
Vertical cavity surface emitting lasers (EPFL)
Quantum Cascade Lasers (ETHZ)
Detectors:
Quantum Cascade detectors (UNINE)
Ge/Si SPADs (EPFL)
IrSens

19. Low dissipation, cw QC lasers
2311cm-1 1730cm-1
1.2W
see poster!
IrSens

20. Detectors:
Quantum cascade detectors,
SiGe CMOS SPAD
IrSens

21. Ge on Si diode test I-V data
low voltage data for diodes with Breakdown near -40V
sizes of 1x1, 1x20, and 40x40 (criterion of 1 µA)
micrometer
good material for a detector @ 1.55µm
IrSens

22. Quantum cascade detector
Detectivity 5*108 jones (175K, 2300/cm) and
1.5*107 jones (250K, 1700/cm)
Cold aperture, NTC, black inner side
IrSens

23. Custom-made QCD preamplifier
1kHz 1MHz Footprint 4 x 4 cm2
• Observed 58 dB of gain in 100mV/nA configuration
• Roughly 25 times more gain than with commercial solution (PA-
9-70 from Judson)
• Almost identically low noise as commercial solution
IrSens

24. Achievements
Near-IR gas system (VCSEL):
– Industrialization in progress
Readiness
Novelty
Mid-IR gas
– Already reached state of the art
Mid-IR liquid
– Key building blocks are validated
– New detectors & lasers
IrSens

25. IrSens team
ETH UNINE
K.Hans, M. Sigrist D. Hofstetter
Y. Bonetti, M. Beck, R. Terazzi, J. DiFrancesco
EPFL FHNWS
E. Kapon, A. Sirbu H. Looser
E. Charbon, M.Aminian
A.Homsy, N. DeRooij, EMPA
L. Hvozdara, Y-C.Chang, H.P Herzig B. Tuzson, A. Manninen, L. Emmenegger
IrSens