Piezoelectric Indentation Probe with Fiber Bragg Grating
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Solution Overview
Problem
Current methods for determining elastic or viscoelastic properties of substrates, particularly in minimally invasive settings like cartilage tissue, face challenges in precision and early detection of degenerative changes, such as in arthrosis, due to limitations in indentation depth and interference from electromagnetic fields.
Innovation Solution
An identification device equipped with a piezoelectric actuator and fiber Bragg gratings allows for precise control and measurement of indentation depth and force with sub-micrometer accuracy, enabling minimally invasive detection of elastic properties without electromagnetic interference, suitable for early arthrosis diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromagnetic-based actuators and sensors are used for indentation measurements, then the device structure can be simpler, but electromagnetic interference impairs measurement precision and reliability
Solution Approach 1:
The patent replaces electromagnetic-based actuators with a piezoelectric actuator that converts electrical energy to mechanical displacement through the piezoelectric effect, and replaces electromagnetic sensors with fiber Bragg grating-based optical sensors that detect force through wavelength shifts. This substitution eliminates electromagnetic interference while maintaining actuation and sensing functions, directly resolving the contradiction between measurement precision and electromagnetic interference.
Solution Approach 2:
The patent introduces optical fibers with fiber Bragg gratings as intermediary elements between the mechanical indentation system and the measurement system. These optical intermediaries convert mechanical force into optical wavelength shifts, providing immune measurement against electromagnetic interference and thereby improving measurement precision without susceptibility to electromagnetic harmful factors.
2Measurement precision
If standard indentation devices with larger probes are used, then the device can handle larger indentation depths, but it cannot achieve high-resolution measurements in thin tissue layers
Solution Approach 1:
The patent applies local quality by using an optical fiber probe with a tip diameter of less than 1 mm, concentrating the measurement function into a highly localized region. This small probe diameter enables high spatial resolution for measuring thin tissue layers (10-100 μm) while the piezoelectric actuator provides the mechanical capability to achieve required indentation depths, thus resolving the contradiction between spatial resolution and indentation depth capability.
3Ease of operation
If a tube with outer diameter less than 1 mm is used for the optical fiber, then minimally invasive measurement is enabled, but the structural stability and force transmission may be compromised
Solution Approach 1:
The patent employs composite material design by combining the optical fiber (glass material) with a protective tube structure. The optical fiber core provides the measurement function while the outer tube (with diameter less than 1 mm) provides mechanical protection and structural stability. This composite approach maintains minimally invasive capability through the small outer diameter while ensuring sufficient structural stability for force transmission during indentation measurements.
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 device achieves high-resolution measurements of elastic properties in thin tissue layers, facilitating early detection of arthrosis and delaying disease progression with minimal invasive stress on the patient.
Implementation Method 1
a piezoelectric actuator for positioning the measuring probe, which is mechanically connected to the measuring probe and which is designed to move the measuring probe towards the substrate to be measured
Implementation Method 2
at least one fiber Bragg grating inscribed in the optical fiber, which is intended to detect a force acting on the tip of the optical fiber
Data Source
AI summary
The invention relates to an indentation device for determining elastic or viscoelastic properties of a substrate, in particular of cartilage tissue in vivo, having a measurement probe for indenting the substrate, which measurement probe comprises a tube and an optical fiber fastened within the tube, wherein the tube has an outside diameter of less than 1 millimeter. Furthermore, the indentation device comprises at least one fiber Bragg grating, which is written into the optical fiber and which is provided for detecting a force acting on the tip of the optical fiber, and a piezoelectric control element for positioning the measurement probe, which is mechanically connected to the measurement probe and which is designed to move the measurement probe onto the substrate to be measured and to press the measurement probe into the substrate. The indentation device is designed to sense the advancement of the measurement probe and the force acting on the tip of the optical fiber.