Miniature wireless concentration meter and method to determine density and concentration
Inventors
Barber, Jeffrey • Weatherall, James C. • Karns, Duane • Smith, Barry T.
Assignees
US Department of Homeland Security
Publication Number
US-12123817-B2
Publication Date
2024-10-22
Expiration Date
2042-05-27
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Abstract
A device to determine density includes a housing, a first transducer disposed in the housing at a first position, and a second transducer disposed in the housing at a second position. The second transducer is located a distance from the first transducer. The device also includes a controller that reads a first output from the first transducer, and reads a second output from the second transducer. The controller determines a density of a liquid based on the first output, the second output, and the distance.
Core Innovation
The invention is a miniature wireless device configured to determine the density of liquids using a housing with multiple transducers disposed at different positions separated by a known distance. The controller reads outputs from these transducers and determines the density based on the outputs and separation distance. Various embodiments use different configurations, such as transducer pairs, transducers with reflectors, or wedge structures, employing transmission or reflection ultrasonic measurements to determine density with high precision.
The device addresses problems identified with conventional density meters that are large, require disturbance or removal of the liquid for measurement, and often cannot distinguish materials with similar dielectric constants, limiting usability in solutions where liquids share similar dielectric properties. The miniature wireless meter enables density and concentration measurements without interrupting the liquid or its container, including under challenging conditions like rotating evaporating flasks during distillation.
The invention includes a capsule package design that can float or sink with controlled buoyancy and maintain orientation, allowing immersion or surface contact while keeping transducers submerged for accurate density measurement. The controller can perform local calculations or wirelessly transmit sensor outputs to external devices for density and concentration determination. The invention encompasses methods for correcting thermal expansion and temperature effects and supports density-based concentration determination for hazardous or sensitive liquids such as hydrogen peroxide solutions.
Claims Coverage
The patent contains multiple independent claims focusing on devices and methods for determining density using specific channel and transducer arrangements within a housing.
A device housing with an outward-facing channel admitting liquid
The housing forms a channel on its outer surface facing outward with no overlapping parts, allowing liquid to directly enter the channel when immersed.
Use of first and second transducers with direct unobstructed line of sight in the channel
Two transducers are disposed in the channel at positions separated by a distance with direct unobstructed line of sight, enabling transmission measurements along the channel.
Controller determining density via transmission measurement based on time-of-flight
The controller uses time-of-flight measurement of signals transmitted through liquid between transducers to determine density, accounting for bulk modulus and measured velocity.
Buoyancy and positioning of transducers at different depths in liquid
When placed in liquid, the device positions transducers at different depths corresponding to the known distance, facilitating pressure or ultrasonic measurements.
Activation of transducers based on electrode status indicating immersion
The device includes electrodes whose status is monitored to detect immersion in liquid and activate the transducers accordingly.
Inclusion of temperature sensing transducer for thermal compensation
A third transducer senses liquid temperature to enable the controller to adjust distance measurements and liquid property calculations, including thermal expansion and bulk modulus corrections.
Variations of transducer types including ultrasonic transceivers and pressure sensors
Claims cover configurations where the transducers are ultrasonic transceivers or pressure sensors.
Alternative device embodiments with spherical or elongated housing and buoyancy control
The device housing can be spherical to sink and roll on container floors or elongated to float while maintaining submerged transducers.
Wireless transmission of sensor outputs for external density determination
The controller includes a transceiver to wirelessly transmit transducer outputs through liquid to an external receiver for density analysis.
Device with a single transducer and reflector arrangement in the channel
A transducer and reflector housed in the channel with direct line of sight enable time-of-flight based transmission measurement to determine liquid density.
Use of transducers including refractive index sensors employing optical cavities
Claims cover devices having refractive index transducers based on Fabry-Pérot cavities, white-light interferometers, or optical microcavities to detect liquid properties.
Methods for density measurement and distillation monitoring with wireless communication
Methods involve immersing the device, reading transducer outputs related to transmission measurements, wirelessly transmitting data to external receivers, and controlling distillation processes based on concentration changes inferred from density measurements.
The independent claims encompass devices with specific outward-facing channels containing transducers or transducer-reflector pairs that perform transmission measurements within liquids, combined with controllers capable of compensating for temperature, controlling buoyancy and orientation, and wirelessly communicating data to external devices. Method claims include using such devices to measure density and monitor distillation processes, particularly for hydrogen peroxide solutions.
Stated Advantages
Enables density and temperature measurements of liquids without disturbing or removing the liquid.
Small, miniature wireless device able to fit through narrow apertures such as evaporating flask openings.
Can operate while container is stationary or in motion, including rotational movement during distillation.
Provides efficient, safe, and cost-effective monitoring for synthesis and evaluation of hazardous liquids.
Supports real-time monitoring and wireless transmission of measurements, facilitating remote control and process automation.
Accommodates liquids with similar dielectric constants unlike prior art density meters using radio frequency or microwave transducers.
Allows thermal compensation for device expansion and liquid property variations to improve measurement accuracy.
Documented Applications
Monitoring density and concentration of hydrogen peroxide solutions during synthesis and distillation processes.
Measuring concentration changes of liquids during rotary evaporator distillations without interrupting the process.
Supporting synthesis and testing of homemade explosives by monitoring hazardous chemical concentrations.
Determining concentrations of solutes such as nitric acid, urea nitrate, ethanol, and salt in various liquid mixtures.
Use in containers like evaporating flasks where the device can be immersed or float and maintain precise orientation.
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