Force sensing strains in soft materials for millisecond-scale blast and impact characterization
Inventors
Assignees
Publication Number
US-12031954-B2
Publication Date
2024-07-09
Expiration Date
2041-02-24
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Abstract
A method of measuring millisecond-scale blast and impact characterization in soft materials includes embedding one or more sensors in soft material, wherein the one or more sensors have mechanical properties approximately matching the soft material; applying a constant current to the one or more sensors; subjecting the soft material to a shock or impact event; measuring a response as a change in voltage; and converting the measured voltage to strain or pressure.
Core Innovation
The invention describes a method to measure millisecond-scale blast and impact characterization in soft materials using embedded sensors with mechanical properties that approximately match the soft material. The method involves applying a constant current to these sensors, subjecting the soft material to a shock or impact event, measuring a response as a change in voltage, and converting that measured voltage to strain or pressure. This method uniquely enables accurate strain measurements within visually-obscured soft materials through impedance matching and dynamic response capability.
The patent addresses the problem that current bio-surrogate model testing lacks commercially available methods to measure strains within surrogate tissue. Existing approaches either use pressure sensors and accelerometers placed only on surrogate surfaces or highly experimental, expensive methods such as metal bead dispersion with high-speed x-ray, which are not suitable for field testing. There is a recognized need for implantable strain sensors able to measure deformation in soft materials to establish direct metrics linked to brain injury and trauma.
The invention utilizes elastomer-encased liquid metal sensors embedded in biofidelic soft materials, thereby creating an impedance match to biological tissue for accurate and unimpeded measurement. The sensors can measure strains ranging from small to moderately large (>20%) under complex deformations, including those occurring at dynamic rates typical of millisecond-scale blast and impact events. Multiple sensor configurations allow for quantifying strain in two or three dimensions, and the system allows for the analysis of wave speeds and pressure changes through soft material using time of flight calculations between distributed sensors.
Claims Coverage
The patent includes multiple independent claims covering methods for measuring strain and pressure in biofidelic human tissue using elastomer-encased sensors with liquid metal channels, applying constant current, and converting voltage changes to strain or pressure, including calculation of pressure wave speed.
Pressure measurement with distributed sensors in biofidelic tissue
Providing at least one elastomer-encased sensor with channels and test leads, embedding multiple pressure sensors distributed along an axis at known distances in biofidelic human tissue mechanically impedance-matched to the elastomer, applying constant current, measuring voltage changes from impact or blast, converting voltage change to pressure, and calculating pressure wave speed using time of flight between sensors.
Strain conversion from voltage changes
Using elastomer-encased strain sensors in biofidelic human tissue and converting measured voltage changes due to impact or blast into strain values on the tissue.
Channel geometry variation
Utilizing channels in the sensors having rectilinear or spiral shapes to tailor sensing capabilities for strain or pressure measurements.
Three-dimensional sensor configuration for volumetric measurements
Embedding a plurality of sensors in a cubic orientation within biofidelic human tissue mechanically impedance-matched to the elastomer, applying constant current, measuring voltage changes under impact or blast, converting voltage to pressure and volumetric strain, and calculating three-dimensional pressure wave speed using time of flight between sensors.
The independent claims collectively cover methods for embedding elastomeric sensors with liquid metal channels in biofidelic tissue to measure and quantify strain and pressure responses during blast or impact events through voltage measurement, sensor configuration variations, and wave speed calculation.
Stated Advantages
Impedance-matching of sensors to biofidelic human tissue for accuracy and unimpeded movement.
Capability to measure small to moderately large (>20%) strains under complex, high-rate dynamic deformations such as millisecond blast and impact events.
Ability to measure deformations within visually obscured gel materials and soft tissues.
Orientation-dependent sensor response improves measurement accuracy by isolating desired strain signals and removing off-axis reflections.
Customizability of sensor size and design to suit a wide range of strain scales and deformation dynamics.
Use of liquid metal sensors provides low stiffness, large strain capability, and long-term stability compared to existing sensor materials.
Potential to improve bio-surrogate testing metrics directly linked to brain injury and trauma, enhancing protection capability quantification.
Documented Applications
Measuring millisecond-scale blast and impact characterization in biofidelic human tissue models, particularly for brain tissue.
Quantifying wave speeds and pressure changes during wave propagation through soft bio-surrogate materials.
Bio-surrogate ballistic impact and helmet testing to improve protective equipment efficacy.
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