Analytical instruments based on InfraRed Absorption Spectroscopy (IRAS) and Gas Chromatography (GC) are today
available only as bench-top instrumentation for forensic labs and bulk analysis. Within the 'DIRAC' project funded by
the European Commission, we are developing an advanced portable sensor, that combines miniaturized GC as its key
chemical separation tool, and IRAS in a Hollow Fiber (HF) as its key analytical tool, to detect and recognize illicit drugs
and key precursors, as bulk and as traces. The HF-IRAS module essentially consists of a broadly tunable External Cavity
(EC) Quantum Cascade Laser (QCL), thermo-electrically cooled MCT detectors, and an infrared hollow fiber at
controlled temperature. The hollow fiber works as a miniaturized gas cell, that can be connected to the output of the GC
column with minimal dead volumes. Indeed, the module has been coupled to GC columns of different internal diameter
and stationary phase, and with a Vapour Phase Pre-concentrator (VPC) that selectively traps target chemicals from the
air. The presentation will report the results of tests made with amphetamines and precursors, as pure substances,
mixtures, and solutions. It will show that the sensor is capable of analyzing all the chemicals of interest, with limits of
detection ranging from a few nanograms to about 100-200 ng. Furthermore, it is suitable to deal with vapours directly
trapped from the headspace of a vessel, and with salts treated in a basic solution. When coupled to FAST GC columns,
the module can analyze multi-components mixes in less than 5 minutes.
The reliable and low-cost quantitative detection of ethylene for food/fruit applications remains an unsolved problem.
Existing commercial systems are able to quantify ethylene (at sub ppm levels) but either they are off-line: require
periodic sample collection and use of reagents or high-cost. We will report on the development of an RFID reader with
onboard micro-machined metal oxide gas sensors aimed at monitoring climacteric fruit during transport and vending.
The developed platform integrates a commercial off the shelf inductive coupling RF transceiver in the 13.56MHz band,
fully compliant with the ISO15693 standard, micro-hotplate gas sensors, driving and readout electronics. If the sensors
are operated at a fixed temperature, the reader could work as an alarm level monitor able to assess the conservation stage
of apples. On the other hand, when the sensors are operated under an optimised temperature-modulation mode, accurate
calibration models for the species that are relevant to assess the conservation stage of apples (i.e., ethylene, acetaldehyde
and ethanol) can be built. Finally, different feature extraction techniques such as the FFT and the Energy Vector will be
used in combination with pattern recognition tools like PLS and PLS-DA to show that our system is able to identify and
quantify the species that are relevant for the application considered.
A multisensing flexible Tag microlab (FTM) with RFID communication capabilities and integrated physical and
chemical sensors for logistic datalogging applications is being developed. For this very specific scenario, several
constraints must be considered: power consumption must be limited for long-term operation, reliable ISO compliant
RFID communication must be implemented, and special encapsulation issues must be faced for reliable sensor
integration. In this work, the developments on application specific electronic interfaces and on ultra-low-power MOX
gas sensors in the framework of the GoodFood FP6 Integrated Project will be reported.
The electronics for sensor control and readout as well as for RFID communication are based on an ultra-low-power
MSP430 microcontroller from Texas Instruments together with a custom RFID front-end based on analog circuitry and
a CPLD digital device, and are designed to guarantee a passive ISO15693 compliant RFID communication in a range up
to 6 cm. A thin film battery for sensor operation is included, allowing data acquisition and storage when no reader field
is present. This design allows the user to access both the traceability and sensor information even when the on-board
battery is exhausted.
The physical sensors for light, temperature and humidity are commercially available devices, while for chemical gas
sensing innovative MOX sensors are developed, based on ultra-low-power micromachined hotplate arrays specifically
designed for flexible Tag integration purposes. A single MOX sensor requires only 8.9 mW for continuous operation,
while temperature modulation and discontinuous sensor operation modes are implemented to further reduce the overall
The development of the custom control and RFID electronics, together with innovative ultra-low-power MOX sensor
arrays with flexible circuit encapsulation techniques will be reported in this work.