Sensor System for Biological Tissue Mechanical Impedance
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Solution Overview
Problem
Existing sensor systems face difficulties in measuring the mechanical impedance of lightweight biological tissues, such as those found in fingers, wrists, and ears, due to limitations in mass and resonant frequency, which affect the quality of audio or haptic output delivery.
Innovation Solution
A sensor system comprising a high-bandwidth shaker, accelerometer, and transducer with a low-mass transducer and rigid stinger, capable of operating within a frequency range of 20 Hz to 20 kHz, is used to measure mechanical impedance by integrating acceleration data to generate velocity data and calculating impedance based on acceleration and force data, with calibration and modeling techniques to account for variables like temperature and hydration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional sensor system is used to measure mechanical impedance of biological tissues, then the system structure is simple, but the measurement precision is insufficient due to mass limitations and resonant frequency constraints
Solution Approach 1:
The sensor system is divided into distinct functional modules: an actuator for applying controlled forces, a transducer for measuring tissue response, and a processor for calculating mechanical impedance. This segmentation allows each component to be optimized independently for its specific function, improving overall measurement precision while managing system complexity through modular design.
Solution Approach 2:
A coupling mechanism serves as an intermediary between the actuator and the biological tissue, enabling effective force transmission while isolating the measurement system from direct tissue contact. This intermediary allows accurate measurement of tissue mechanical properties without the mass and frequency constraints that would otherwise limit traditional sensor systems.
2Reliability
If the transducer mass is increased to improve measurement stability, then the measurement reliability improves, but the ability to measure lightweight biological tissues deteriorates
Solution Approach 1:
The system compensates for the low mass of the transducer by using a rigid coupling mechanism that provides mechanical stability and force transmission capability. The coupling acts as a structural counterbalance, allowing the lightweight transducer to reliably measure tissue mechanical properties without being constrained by its own mass limitations.
Solution Approach 2:
The actuator applies preliminary controlled forces to the tissue through the coupling mechanism before the transducer makes direct contact with the tissue. This preliminary action establishes a stable measurement baseline and ensures that the lightweight transducer operates within its optimal measurement range, improving reliability without requiring increased transducer mass.
3Adaptability or versatility
If the frequency range is extended to 20 Hz to 20 kHz for comprehensive tissue characterization, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The actuator is designed as a universal component capable of operating across the entire 20 Hz to 20 kHz frequency range, eliminating the need for multiple specialized actuators for different frequency bands. This multi-functional design achieves comprehensive tissue characterization while managing complexity through a single versatile actuation system.
Solution Approach 2:
The system dynamically adjusts operating parameters including frequency, amplitude, and phase based on real-time tissue response measurements. This dynamic adaptation allows the sensor system to optimize its measurement approach for different tissue types and conditions across the full frequency range, enhancing versatility while using intelligent control to manage system complexity.
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
This system effectively measures mechanical impedance across a wide frequency range, improving the perception of audio or haptic content and enabling personalized user profiles and device operation optimization.
Implementation Method 1
an accelerometer coupled with the actuator. The accelerometer can output an acceleration signal responsive to at least the motion of the actuator
Implementation Method 2
The transducer can output force data, so that the mechanical impedance can be calculated based on the acceleration data (e.g., velocity data generated from the acceleration data) and the force data
Implementation Method 3
The high-bandwidth shaker can operate as an actuator to cause the accelerometer, stinger, and transducer to move based on how the shaker is controlled. For example, the shaker can cause oscillation of the other components in a frequency range of interest for measurement, such as 20 Hz to 20 kHz
Data Source
AI summary
A sensor system includes an actuator, an accelerometer coupled with the actuator, a rigid member, a transducer, and one or more processors. The actuator generates motion. The accelerometer outputs an acceleration signal responsive to at least the motion of the actuator. The rigid member extends from a first end coupled with the accelerometer to a second end. The transducer is coupled with the second end of the rigid member. The transducer can be configured to couple with a load, and can output a force signal responsive to at least a portion of the motion of the actuator transmitted to the transducer via the rigid member. The one or more processors determine a mechanical impedance of the load based at least on the acceleration signal and the force signal.