Robust engineering
The loop between development and rigorous field-testing

Robust engineering
The loop between development and rigorous field-testing

The engineering challenges

Making bench-top chemical analysis techniques to work outside the lab is a much demanding job. Many different things can go wrong. This is especially true for chemical detectors on board UAVs.  Portability may not be enough, field robustness may be limited, communications may have shadows, operation and handling may not be ergonomic, environmental conditions may become extreme in terms of temperatures (-10 to 50oC), humidity (up to 100% relative humidity), wind speed (more than 50 Km per hour) and perhaps heavy rain. Under such conditions there is still the need to prove that the field instrument is efficient and productive, it can be incorporated in a wide range of missions and most important of all that produces reliable measurements. 

Continuous field testing is the answer; rigorous field testing in a loop with the development provides robust and rugged field instruments.

Promoting the use of field chemical detectors and analyzers: Portability,  robustness, data transmission, deployment and modularity.

Field (on-site) Chemical Analysis and technology is a rapidly developing area of science, technology and instrumentation market as one can see from what is presented in PITTCON, SPIE and other conferences and exhibitions. Field Chemical Analysis unifies the strengths of multidisciplinary expertise to create portable systems capable of detecting, identifying, and transmitting chemical data.

Field portability and robustness are quite important in field chemical analysis.

Portability can be defined as “easy to transportation” and therefore instrument size(shape?) and weight become important. From previous experiences and the operational perspective, it is possible to broadly categorize field instruments in wearable (few grams up to 100g), hand portable (up to 3kg), backpack (up to 25kg) and luggage type (up to 30kg).

Field robustness means many different things for different people such as “stability of shape and operation” or “continuous field working” in different environmental conditions (e.g., weather and dust proof or more broadly speaking MIL-STA-810G type of devices). Field robust operation means also stable and continuous power supply. This is absolutely necessary, especially, for chemical detectors on board UAVs. For pneumatic-based instruments stable and continuous power supply is quite important due, mainly, to the use of pumps even when high vacuum is not required. Use of instruments in fixed sites, in the field, has certain advantages for power supply.

Field Chemical Analysis needs to use wireless communications for a number of reasons; remote and continuous monitoring, situational awareness, providing real time information to coordinating personnel, tag and track purposes and for remote back up purposes. Communication protocols such as 802.11, 802.15.4, 802.16, GPRS, UMTS can be used for reliable, secure and cost-effective transmission.

In Field Chemical Instrumentation, field deployment is a critical parameter since deployment time is mainly consumed for stabilizing temperatures and, if exists, the vacuum. The startup time need to be, generally, in less than half an hour (field calibration included). However, in some cases it is needed to be few minutes.  Use of the chemical detector/analyzer on board UAVs is an advantage for fast deployment and screening large areas. 

In terms of modularity, front end and back-end modules of a field instrument are important for high performance and throughput (sampling, preconcentration, separation). In this case T4i engineering Sample Modulation Separation (SMS) as a front-end module has unique advantages for atmospheric and vacuum chemical detectors.  For the detection and analysis of the compounds of interest, separation of VOCs, as well as, separation of matrix interferences is proposed. However, when GC is used in the field, supply of carrier gas can become a problem especially for roving ground systems, hand-held or back pack types of devices and on-board UAVs.

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