Hydrocarbon Sensor With Swelling Silicone Actuator
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Solution Overview
Problem
Existing hydrocarbon sensors face limitations such as inability to reset after exposure to non-volatile fuels, finite exposure cycles leading to sensor degradation, fragility when saturated with hydrocarbon liquids, and damage from long-term water exposure, resulting in reduced lifespan and increased maintenance needs.
Innovation Solution
A fluid sensor design featuring stacked silicone wafers within a housing with mesh screens, which disperse hydrocarbons and cause the wafers to swell, physically moving a mechanical actuator to trigger a switch, allowing for faster response and reset capabilities, and incorporating a sealing mechanism to prevent water damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone matrix sensors are used to detect hydrocarbons, then hydrocarbon detection capability is improved, but the sensor cannot be reset after exposure to non-volatile fuels and has limited exposure cycles
Solution Approach 1:
The sensor is divided into separate functional components: a rigid substrate, a adhesive layer, and a silicone sensing element. This segmentation allows the silicone element to be replaced or reset independently without damaging the substrate, enabling multiple exposure cycles and improving sensor lifespan.
Solution Approach 2:
The silicone sensing element can be discarded after saturation with non-volatile fuels and replaced with a fresh element. The rigid substrate and adhesive layer are recovered and reused, allowing the sensor to be reset and extended its operational life while maintaining detection capability.
2Speed
If thin silicone matrix film is used for sensor operation, then response speed is improved, but the bond between matrix and substrate loosens after finite expansion/contraction cycles
Solution Approach 1:
The sensor structure is segmented into a rigid substrate, adhesive layer, and silicone element. The rigid substrate provides a stable bonding surface that does not deform during expansion/contraction cycles, while the adhesive layer accommodates the silicone's dimensional changes, preventing bond loosening and maintaining response speed.
Solution Approach 2:
The adhesive layer's properties are optimized to accommodate the silicone element's expansion and contraction without compromising the bond to the substrate. This allows the thin silicone film to maintain fast response while the adhesive absorbs the mechanical stress of repeated cycling.
3Measurement precision
If silicone sensor elements are saturated with hydrocarbon liquid, then detection sensitivity is improved, but the sensor becomes fragile and prone to delamination
Solution Approach 1:
The sensor is segmented into a rigid substrate and a removable silicone element. When the silicone becomes saturated and fragile, only the element needs to be replaced, not the entire sensor assembly. This maintains detection sensitivity while restoring structural integrity.
Solution Approach 2:
The fragile silicone element saturated with hydrocarbon is discarded and replaced with a fresh element, while the rigid substrate and other components are recovered and reused. This eliminates the fragility issue while maintaining the detection capability achieved through saturation.
4Reliability
If traditional hydrocarbon sensor design is used, then hydrocarbon detection is achieved, but water exposure damages the sensor element or substrate
Solution Approach 1:
A hydrophobic coating is applied as an intermediary layer between the environment and the sensor components. This coating repels water while allowing hydrocarbon detection to proceed, protecting both the silicone element and substrate from water damage without interfering with hydrocarbon sensing capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sensor effectively detects hydrocarbons, resets easily after exposure to volatile and non-volatile fuels, and withstands water immersion, reducing false alarms and extending sensor lifespan by preventing delamination and degradation.
Implementation Method 1
the silicone wafers are capable of absorbing and swelling in the presence of a liquid hydrocarbon
Implementation Method 2
the silicone wafers swell or expand
Data Source
AI summary
A fluid sensor comprises a sensor housing, a sensor package, an actuator and a switch. The sensor package is disposed within the sensor housing and includes first and second screens and at least one sensing membrane. The sensing membrane is disposed between the first and second screens and is adapted to expand when exposed to a predetermined quantity of a first predetermined fluid. The actuator is disposed proximate the sensor package within the sensor housing and moveable between a first position and a second position through an intermediate position. The switch is disposed proximate the actuator and is operable between closed and open positions. When the actuator is in the second position at least a portion of the actuator depresses the switch to control an electrical circuit connected therewith.