Better solutions for air quality awareness

GPI is offering major advance in gas detection technology by offering complete monitoring solutions based on sensitive next-generation instruments that deliver superior measurements for sensing, identifying, analyzing, quantifying and mapping fugitive emissions from natural gas production sites and pipelines. This is the initial market targeted by GPI. Though not the only one, it is the largest, most immediate, and most accessible, with known interested parties. Initial focus will be on methane (CH4), but the technology can be applied to many gases, as presented below.



A guard or soldier who controls the security at borders, whose job is to stand and keep watch.

PIGC zoom

Conceptual view of PIGC™Sentinel sensor in operation.


GPI has conceived and patented a breakthrough sensor technology, the Pupil Imaging Gas Correlation, PIGC™ (pronounced “pigzy”), which provides exceptional resolution, and coverage for various gas sensing applications. The PIGC technology uses a variation of the well-known gas-correlation technique[1] implemented for the HALOE and MOPITT satellite instruments that were flown on successful NASA missions in the early 2000s. Simply put, it uses an internal tube filled with a reference gas to compare the incoming light with a specific spectral signature to match, much like a fingerprint. Detection is done along a line of sight between the sensor and a light source, using the Sun for vertical total atmospheric monitoring, or a bright incandescent light bulb for horizontal fence line monitoring applications.

GPI will implement this technology in the form of its “PIGC™Sentinel” commercial line of product, a remote sensor providing continuous atmospheric column measurements with high precision, sensitivity, and accuracy. The instrument is designed to quantify the origin, concentration, and fluxes of specific gases over a series of ground locations, allowing better tracking of plumes and identification of sources. This spectrometer takes the form of a shoebox-sized optical instrument that combines several proven technologies. For example, the PIGC™Sentinel benefits from advances in uncooled detector arrays, GPS, solar cell panels, cheap miniature processors, wireless communication, small inexpensive pointing systems and novel spectrometric techniques combined to produce a compact trace gas sensor capable of remote connection and autonomous operation.

Built with low-cost, off-the-shelf components, this < $5 k targeted price instrument can outperform $100 k to $400 k instruments, thus rivaling the most complex, expensive laboratory spectrometers.

PIGC™Sentinel can provide quasi-continuous detection of greenhouse gases (GHGs)[2], among which methane being of immediate concern. The PIGC approach is readily extendable to many other pollutants and toxic gases (see HYPERLINK) where dangerous plumes of poisonous or explosive emanations can be instantly detected when they pass between a PIGC sensor and the observed light source. Moreover, the design can simultaneously accommodate many of such gases. For more details, consult document "Product overview".

The sensitivity of a similar sensor has already been verified in a NASA laboratory SBIR program (NNX10CB45C). Moreover, GPI has recently built an Alpha Prototype for functionality demonstration that is showing excellent performance through initial testing over a limited range of operating conditions (see HYPERLINK), thus validating the concept and its implementation into a small form factor.

The PIGC™Sentinel instrument is designed to quantify the concentration and fluxes of specific gases over a series of ground locations, allowing better tracking of plumes and identification of sources. A network of ground sensors could provide full atmosphere monitoring for broad outdoor measurements and total gas fluxes over an enclosed perimeter. Moreover, it would potentially be able to provide all day measurements, through moderately cloudy skies, and even in moonlit nights.

With the availability of this low-cost instrument, it is now possible to deploy a series of sensors to monitor air quality around almost any site (see HYPERLINK). For example, it can be determined, for any area encircled with solar-pointed PIGCs, the amount of targeted gas (gas for which the PIGCs are configured to measure), or fluxes being released from the area or getting into the area from outside sources. A grid of these instruments therefore provides the comprehensive observations necessary to frequently and accurately quantify the atmospheric abundance of key greenhouse and pollutant gases. See HYPERLINK for more details about operational scenarios.

PIGC™Sentinel can be implemented for only a small fraction of the cost of existing solutions. Because of its affordability, a network of ground based PIGC™Sentinel sensors can be implemented at any scale: for example monitoring a single compressor, an industry plant, an entire city, a whole gas production field, a country, or even a continent. For remote sensing of greenhouse gases, such a network would surpass satellite accuracy, resolution, and source specificity, at far lower costs.


[1] Gas Filter Correlation Radiometry (GFCR);;

[2] The three principal greenhouse gases are Methane (CH4), Carbon dioxide (CO2), and Nitrous oxide (N2O)