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Medical balloon is a medical device that is introduced into the human body's lumen or blood vessels through a catheter, and expands, supports, or releases drugs through inflation or liquid filling. It is widely used in the treatment of diseases in cardiovascular, urinary, digestive, and other fields, mainly for the following functions.
Dilation stenosis: This is the most basic and important function, which uses physical expansion force to open the narrowed lumen (blood vessels, digestive tract, airway, urinary tract, etc.) and restore the patency of the lumen.
Relieve obstruction: By dilating narrow channels, such as prostate hyperplasia, the obstruction of the lumen is relieved, and the normal flow of blood, urine, food, bile, gas, etc. is restored.
Delivery and anchoring devices: As carriers of functional implants, implantable medical devices such as stents or valves are precisely delivered to the target location and fixed in place through expansion.
Temporary occlusion: In specific situations such as injection vessel rupture, an inflated balloon can play a role in temporary occlusion, hemostasis, or blocking blood flow.
The common measurement methods on the market have certain limitations.
Slicing microscope method: The accuracy can meet the measurement requirements, but it is a destructive test and cannot achieve full inspection; Usually, the length of a single balloon can reach several tens of centimeters, and the section microscopy method can only select a fixed cross-section for measurement and evaluation, which is not representative enough; The slicing measurement method also tests the measurement skills of operators, and if the cross-section is prevented from tilting, significant thickness deviations may occur.
Micrometer contact method: The material of the balloon is usually a polymer with a relatively soft texture. When measured with a micrometer, it is prone to deformation, resulting in inaccurate measurement data.
Ultrasonic measurement method: Due to the limitations of frequency and resolution, it is difficult to identify the echo signals of thin-walled balloons using ultrasonic measurement method, which makes it difficult to meet the requirements of precise thickness control.
X-ray method: The measurement accuracy is acceptable, but the equipment cost is high, there are radiation protection requirements, and the convenience of frequent use on the production line is insufficient.
From an engineering perspective, measuring the wall thickness of a balloon is not just about filling out the specifications on the form, it is directly linked to the usability and safety of the product, and mainly has the following impacts.
Pressure safety: If the wall thickness of the balloon is too thin, the balloon may burst during high-pressure filling, which is not a small matter, and the risk of vascular injury or embolism increases.
Expansion accuracy: The wall thickness of the balloon is uniform, and only when the balloon is inflated and expanded can it reach the designed diameter, be able to be stretched open, and the stent is firmly attached to the wall, can it play its due role.
Transportability: Control the wall thickness of the balloon. Under normal circumstances, the folded outer diameter can only be made small, allowing the balloon to pass through tortuous blood vessels.
Performance predictability: Only when the thickness of the structural layer is stable, can the strength and fatigue life of the material be predicted, and even the volatilization effect of the drug coating be reproducible.
We use the Filmetrics F40 optical film thickness gauge, which has a small light spot and good measurement adaptability, and can measure irregular surfaces. F40 is widely used in the medical field. We have used it to measure the thickness of drug coatings on cardiac stents and the super lubricating coating on the surface of medical catheters. Its principle is not complicated: a beam of white light is projected onto the surface of the film, and the interference fringes generated by the light reflected back from the upper and lower surfaces can be calculated through algorithms.
In the initial measurement, some problems were encountered. The balloon was round and soft, and when it was not inflated, it was still milky white. It could not form effective interference and could not receive effective signals. Later, we tried several times and found a feasible method: first inflate or inject water into the balloon and let it hold up. After being stretched open, the cyst wall is stretched thin, and the microscopic structures inside the material that cause scattering are flattened, resulting in increased transparency. At this point, when measuring again, the interference signal comes out and the effect is quite good.
F40 can be freely selected for measurement on the balloon - body, cone, shoulder, folding area. Just inflate or inject water into the balloon, and fix it after inflation. Align and click on measure. The result is accurate and fast in less than a second.
Optical methods are not omnipotent. If the balloon contains a metal shielding layer, a metal coating, or too much filler, and the light cannot pass through, then an optical film thickness gauge cannot be used for measurement. But most conventional balloons on the market - coronary, urinary, and gastrointestinal - can basically handle F40. If you are also struggling with measuring the thickness of the balloon, please feel free to contact us and send samples over. We offer free testing and provide you with a complete measurement report.
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