RF Applicator Waveguide Insert Gap Filling
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Solution Overview
Problem
Sub-optimal coupling of RF applicators to tissue in thermoacoustic imaging systems leads to inefficient energy transfer, reduced heating rates, non-uniform energy deposition, tissue hotspots, overheating, and poor image quality due to air gaps between waveguide and solid inserts, which alter frequency characteristics unpredictably.
Innovation Solution
An RF applicator with an open-ended hollow waveguide and a solid insert having a recess, filled with a ceramic wax composite or conductive material to eliminate air gaps and ensure consistent frequency emission, featuring a ceramic insert with a high relative permittivity and a filler material with a melting point between 40°C and 120°C to solidify and fill gaps between the waveguide and insert surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid insert is fitted into a waveguide to provide filtering, then electromagnetic wave filtering is improved, but air gaps form between the waveguide and insert causing unpredictable frequency characteristics
Solution Approach 1:
A filler material is introduced as an intermediary substance between the waveguide and solid insert to eliminate air gaps. The filler material fills the spaces created by manufacturing tolerances and surface irregularities, ensuring consistent electrical contact and stable frequency characteristics without requiring extremely tight manufacturing precision.
Solution Approach 2:
The electrical parameters (permittivity and conductivity) of the filler material are carefully selected and adjusted to match the surrounding materials. By changing the material parameters of the filler substance, the overall electrical characteristics of the waveguide-insert assembly are maintained, eliminating the harmful effects of air gaps while preserving the desired filtering performance.
2Productivity
If RF applicator coupling to tissue is improved, then energy transfer efficiency is improved, but variability in tissue properties makes consistent coupling difficult
Solution Approach 1:
The filler material's electrical parameters (permittivity and conductivity) are specifically tuned to compensate for variations in tissue properties. By adjusting these material parameters, the RF applicator maintains consistent energy transfer efficiency across different tissue types and conditions, effectively adapting to tissue variability through material property optimization.
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
Enhances RF energy delivery to tissue with improved uniformity and consistency, reducing tissue hotspots and enhancing image quality by eliminating air gaps and maintaining desired frequency characteristics.
Implementation Method 1
filler material between facing surfaces of the waveguide and the insert to fill gaps therebetween
Implementation Method 2
the insert is formed of ceramic material. The ceramic material may have a real relative permittivity greater than 10
Implementation Method 3
a radio frequency (RF) source extending through the aperture and into the recess and being configured to generate RF energy pulses
Implementation Method 4
it is common to employ waveguides to guide electromagnetic waves or sound with minimal loss of energy by restricting expansion of the electromagnetic waves propagating within the waveguides
Data Source
AI summary
A method for manufacturing a radio frequency (RF) applicator which includes covering a ceramic insert with a coating, wherein the ceramic insert has dimensions that substantially match an internal volume of an open-ended, hollow waveguide, and wherein the ceramic insert has a recess therein configured to accept a radio frequency emitter, heating the waveguide to a temperature that is above a melting point of the coating, placing the coated ceramic insert into the internal volume of the heated waveguide, wherein the internal volume is completely filled except for the recess, and cooling the waveguide, ceramic insert, and coating to a temperature below the melting point of the coating so that the coating solidifies and fills gaps between facing surfaces of the insert and the waveguide.