Illuminated ultra-thin chemical sensors, and systems and methods comprising same
Inventors
Ménard, Jean-Michel • Luican-Mayer, Adina Anamaria • Rautela, Ranjana
Assignees
Publication Number
US-12013364-B2
Publication Date
2024-06-18
Expiration Date
2040-10-15
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Abstract
Described are various embodiments of a system and method for selectively identifying the presence of a designated chemical species within a chemical sample using a two-dimensional sensor, which, when exposed to illumination, provides a differentiable adsorption sensor response signal for chemical identification.
Core Innovation
The invention relates to illuminated ultra-thin chemical sensors, specifically two-dimensional (2D) sensors such as graphene-based sensors, that when exposed to designated illumination produce a differentiable adsorption sensor response signal enabling selective identification of designated chemical species within a chemical sample. The system and method involve exposing a 2D sensor to a chemical sample, illuminating the sensor to induce a differentiable adsorption response, acquiring sensor signals under illumination and optionally in absence of illumination, and identifying the presence of particular chemical species based on the distinctive responses.
The problem addressed is the need for enhanced sensitivity and selectivity in chemical sensing using ultra-thin materials such as graphene, which is typically challenged by imperfections like surface polymer residues and doping variations. Existing methods lacked the ability to distinguish different chemicals robustly, particularly under ambient conditions, due to overlapping sensor signals and limited differentiation. By employing illumination, including ultraviolet light, and controlling surface properties such as polymethylmethacrylate (PMMA) residues, the disclosed embodiments improve response amplitude and generate distinguishable signals enabling selective chemical identification.
The invention additionally addresses the impact of surface treatment such as baking to modify or reduce sensor surface residues, thereby tuning electrical properties and sensor responsiveness. The overall system comprises not only the 2D sensor and illumination source but also signal acquisition and processing devices to compare response signals with and without illumination. This approach leads to inversion or sign reversal in resistance changes for certain chemicals under illumination, producing an asymmetric dispersion in sensor responses, which serves as a basis for enhanced chemical selectivity.
Claims Coverage
The patent claims disclose one independent system claim encompassing the main inventive features related to employing a two-dimensional sensor with surface residue responsive to illumination, a source of illumination generating differentiable adsorption responses, and signal acquisition for chemical identification.
Two-dimensional sensor with surface residue providing unique electrical sensing properties
The system uses a two-dimensional sensor comprising sensor surface residue that yields designated electrical sensing properties leading to respective differentiable adsorption sensor responses to different chemical species as a function of illumination.
Illumination inducing differentiable adsorption sensor responses
The system incorporates a source of illumination that induces, according to the sensor's electrical properties, respective differentiable adsorption sensor responses characterized by a sign reversal in resistance change for one chemical under illumination compared to absence of illumination, while responses to another chemical lack this reversal, enabling differentiation.
Signal acquisition and comparison for differential chemical identification
The system includes a signal acquisition device with a digital processor configured to acquire sensor signals under illumination and without, compare the signals, and upon detecting the sign reversal of resistance change, differentially identify the presence of corresponding designated chemical species.
Utilization of graphene and polymethylmethacrylate (PMMA) residue
The two-dimensional sensor may comprise a graphene sheet with polymethylmethacrylate residue defined by a molecular weight of about 950,000 g/mol prepared in an anisole solution of about 6% concentration.
Use of ultraviolet wavelength illumination
The system employs illumination with a wavelength corresponding to ultraviolet light, specifically between 300 nm and 400 nm.
Pre-baking of the two-dimensional sensor to produce annealed surface residue
Prior to use, the two-dimensional sensor undergoes a baking process modifying area, density, thickness, or electrical properties of the sensor surface residue to optimize sensing performance.
Characterization of asymmetric dispersion in sensor response
Only one of the respective designated differentiable adsorption sensor responses exhibits an asymmetric dispersion, facilitating chemical species differentiation.
The claims cover a system that integrates a 2D sensor with surface residue, controlled illumination inducing differentiated sensor responses including sign reversals of resistance changes, and signal acquisition with processing to selectively identify distinct chemical species, employing embodiments of graphene sensors, PMMA residues, ultraviolet illumination, and surface conditioning via baking.
Stated Advantages
Enhanced chemical detection sensitivity through illumination-induced increase in sensor response magnitude.
Improved chemical selectivity by generating differentiable sensor responses, including polarity reversals and asymmetric dispersion, to distinguish between chemical species.
Increased signal-to-noise ratio enabled by illumination, enabling more reliable detection.
Controllable sensor performance through baking to modify surface residue properties, thereby tuning sensitivity and selectivity.
Capability to detect multiple chemicals such as ethanol and water vapor with distinguishable response signatures.
Documented Applications
Quality control applications requiring sensitive and selective chemical detection.
Military applications involving detection of trace chemicals.
Environmental monitoring and public safety through precise identification of gaseous chemical species.
Chemical sensing systems incorporating graphene-based sensors illuminated by ultraviolet light for selective detection of ethanol and water vapor.
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