Acoustic Sensor Assembly with Faraday Cage Shielding
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Solution Overview
Problem
There is a need for a reliable acoustic sensor suited for measuring bodily sounds in noisy environments, which can withstand stress, strain, and movement while maintaining accurate measurements.
Innovation Solution
The acoustic sensor incorporates an electrical shielding barrier to reduce external noise, an acoustic coupler for improved signal coupling and electrical isolation, and an attachment element with a resilient elongate member to ensure secure and consistent contact with the patient's skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric membranes are used for acoustic sensing, then frequency range and dielectric strength are improved, but susceptibility to electrical noise in noisy environments worsens
Solution Approach 1:
A Faraday cage is introduced as an intermediary structure between the external noisy environment and the piezoelectric sensing element. The cage is constructed from conductive material and connected to ground, creating an electromagnetic shield that blocks external electrical noise while allowing acoustic vibrations to pass through to the sensor.
Solution Approach 2:
The patent employs a simple, inexpensive conductive mesh or foil structure for the Faraday cage rather than complex active noise cancellation systems. This passive shielding approach uses readily available conductive materials that can be easily integrated into the sensor housing, providing cost-effective noise protection.
2Reliability
If the sensor is made secure against movement and strain, then measurement stability is improved, but comfort and ease of operation worsens
Solution Approach 1:
The sensor incorporates a flexible headpiece made from elastic or viscoelastic material that can conform to the contours of the patient's head. This flexible construction allows the sensor to move with the patient's head movements rather than creating rigid constraints, reducing discomfort while maintaining secure attachment and stable acoustic coupling.
Solution Approach 2:
The mounting mechanism uses elastic elements that provide dynamic compliance, allowing the sensor to adapt its position and pressure in real-time as the patient moves. This dynamic adjustment maintains optimal acoustic coupling without requiring excessive clamping force, thereby preserving measurement stability while enhancing comfort.
3Measurement precision
If acoustic coupling is improved through direct contact, then signal quality is improved, but electrical isolation and patient safety worsen
Solution Approach 1:
An acoustic coupling medium such as gel or foam is introduced as an intermediary between the patient's skin and the piezoelectric sensor. This coupling medium provides excellent acoustic impedance matching for high-fidelity sound transmission while simultaneously serving as an electrical insulator that breaks any potential galvanic pathway between the sensor and the patient's body.
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 sensor provides accurate and robust measurement of bodily sounds under various conditions, including noisy environments, by effectively shielding against electrical noise, improving signal coupling, and maintaining secure attachment to the patient.
Implementation Method 1
The 'piezoelectric effect' is the appearance of an electric potential and current across certain faces of a crystal when it is subjected to mechanical stresses. Due to their capacity to convert mechanical deformation into an electric voltage, piezoelectric crystals have been broadly used in devices such as transducers, strain gauges and microphones.
Implementation Method 2
The electrical shielding barrier can include one or more layers which form a Faraday cage around the piezoelectric element, for example, and which distribute external electrical noise substantially equally to first and second electrical poles of the piezoelectric sensing element.
Data Source
AI summary
An acoustic sensor is configured to provide accurate and robust measurement of bodily sounds under a variety of conditions, such as in noisy environments or in situations in which stress, strain, or movement may be imparted onto a sensor with respect to a patient. Embodiments of the sensor provide a conformable electrical shielding, as well as improved acoustic and mechanical coupling between the sensor and the measurement site.