Polymer Absorption (PA) Sensor Technology

Developed in close cooperation with the petroleum industry

About PA Sensors

Overview

Typically, a PA sensor is composed of an elastomeric polymer matrix that is embedded with micro- and nano-sized conducting particles. The resulting composite material is deposited between two electrodes on a printed circuit board (PCB) and has a characteristic baseline resistance. The PA sensor operates via absorption and subsequent matrix expansion (swelling) resulting from contact with target hydrocarbons. Upon swelling, the interparticle distance of the embedded conducting micro- and nanoparticles increases, resulting in a PA sensor baseline resistance change. If the detected resistance change is greater than an applied threshold, it can be used by an external system to trigger an alert.

Historical Challenges

Commercially available PA sensor technologies have not changed considerably since they were first developed in the mid-1950s. Two main factors contributed to the developmental stagnation:

material degradation from thermal and hydrolytic weathering, and
cross-sensitivity to thermal fluctuations and water absorption (submersion/humidity).

Highlights

Syscor has designed and produced a new generation of hydrocarbon leak detection PA sensor that overcomes historical challenges. The PA sensor is thoroughly tested and systematically qualified to detect hydrocarbons (butane and heavier) in air, underground, and within water bodies (including ice). Furthermore, it is designed to operate in a wide range of environments (icy, wet, humid, or dry) and temperatures.

Detects butane (C₄) and heavier hydrocarbons such as synthetic blends, dilbit, synbit, crude oil, gasoline, and diesel fuel
Methane immunity (no false alarms triggered by methane)
High signal-to-noise ratio
Moisture resistance
Minimal power usage
Possible to reuse after hydrocarbon contact (reversible)
Operating temperature:-40°C to +60°C (-40°F to +140°F)

PA Sensor Application within Syscor Devices

Syscor’s HCD Hydrocarbon Detector Probe and HCDW Hydrocarbon Detector Probe with Water Level are equipped with two PA sensors within perforated stainless steel enclosures. Up to two sensor probes may be wired to Syscor’s PCU-X01 Sensor Hub or PCU-X11 Inclinometer when deployed.

Syscor’s Rapid Deployment External Leak Detection System (ELDS) utilizes two PA sensors within each HCD-P Hydrocarbon Detector Probe, which have perforated high density polyethylene (HDPE) enclosures. Up to two HCD-Ps may wired to the Rapid Deployment ELDS when deployed.

PA sensor surface topology images - what they show us

Figure A shows surface topology 3D rendering produced by an optical microscope used for surface roughness calculations; lighter colors represent higher surface amplitudes than dark colors (scale left of A).
Figure B shows a 2D rendering of Syscor's PA sensor surface topology; dark regions are lower in amplitude than light regions. Inset in Figure B presents contact angle measurements that show high surface hydrophobicity, rendering the polymer absorption sensors highly resistant to degradation from extended exposure to water and ice.
Figures C and D present cross-sectional scanning electron microscopy (SEM) scans of Syscor's PA sensor. The dark regions are voids within the sensor’s composite material; these voids help increase the PA sensor surface area for faster hydrocarbon detection kinetics. All scale bars = 100 μm

Documents

PDF HCD Hydrocarbon Detector Spec Sheet
PDF HCDW Hydrocarbon Detector with Water Level Spec Sheet
PDF HCD-P Hydrocarbon Detector with HDPE Enclosure Spec Sheet