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Sensor to detect endothelialization on an active coronary stent.

Musick KM, Coffey AC, Irazoqui PP - Biomed Eng Online (2010)

Bottom Line: After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever.The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications.This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA. kmmusick@purdue.edu

ABSTRACT

Background: A serious complication with drug-eluting coronary stents is late thrombosis, caused by exposed stent struts not covered by endothelial cells in the healing process. Real-time detection of this healing process could guide physicians for more individualized anti-platelet therapy. Here we present work towards developing a sensor to detect this healing process. Sensors on several stent struts could give information about the heterogeneity of healing across the stent.

Methods: A piezoelectric microcantilever was insulated with parylene and demonstrated as an endothelialization detector for incorporation within an active coronary stent. After initial characterization, endothelial cells were plated onto the cantilever surface. After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever. This shift was then detected electrically with an LCR meter. The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications.

Results: A cell density of 1300 cells/mm2 on the cantilever surface is detected.

Conclusions: We have developed a self-actuating, self-sensing device for detecting the presence of endothelial cells on a surface. The device is biocompatible and functions reliably in ionic liquids, making it appropriate for implantable applications. This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation. Anti-platelet therapy can be adjusted in real-time with respect to a patient's level of healing and hemorrhaging risks.

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Cell chamber. Top view of cantilever cell chamber. Glass tube is 1 cm in diameter.
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Figure 3: Cell chamber. Top view of cantilever cell chamber. Glass tube is 1 cm in diameter.

Mentions: A custom chamber was devised to perform measurements in fluid (Figure 3). The fluid was confined in a glass tube (diameter = 1 cm, height = 3.5 cm) placed on top of a standard glass slide. The cantilever was placed under the rim of the tube so the cantilever itself was inside the tubing and the contact pads remained outside the tubing. The base of the tube was sealed with silicone to prevent leakage. Parylene C was deposited on the device to a thickness of 1.5 μm with a parylene CVD furnace (Specialty Coating Systems), creating water-resistant insulation on the cantilever. Parylene was selected as it is inert and should not suffer corrosion when implanted long-term. Parylene is also the primer layer on the CYPHER drug-eluting stent [15]. Thus, it should be feasible to use this cantilever in conjunction with the existing CYPHER stent so that the stent and cantilever could have similar coatings. An O2-plasma treatment (55 W for 30 s) effectively created a hydrophilic surface on the parylene to promote cell attachment. This step also sterilized the device.


Sensor to detect endothelialization on an active coronary stent.

Musick KM, Coffey AC, Irazoqui PP - Biomed Eng Online (2010)

Cell chamber. Top view of cantilever cell chamber. Glass tube is 1 cm in diameter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2992534&req=5

Figure 3: Cell chamber. Top view of cantilever cell chamber. Glass tube is 1 cm in diameter.
Mentions: A custom chamber was devised to perform measurements in fluid (Figure 3). The fluid was confined in a glass tube (diameter = 1 cm, height = 3.5 cm) placed on top of a standard glass slide. The cantilever was placed under the rim of the tube so the cantilever itself was inside the tubing and the contact pads remained outside the tubing. The base of the tube was sealed with silicone to prevent leakage. Parylene C was deposited on the device to a thickness of 1.5 μm with a parylene CVD furnace (Specialty Coating Systems), creating water-resistant insulation on the cantilever. Parylene was selected as it is inert and should not suffer corrosion when implanted long-term. Parylene is also the primer layer on the CYPHER drug-eluting stent [15]. Thus, it should be feasible to use this cantilever in conjunction with the existing CYPHER stent so that the stent and cantilever could have similar coatings. An O2-plasma treatment (55 W for 30 s) effectively created a hydrophilic surface on the parylene to promote cell attachment. This step also sterilized the device.

Bottom Line: After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever.The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications.This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA. kmmusick@purdue.edu

ABSTRACT

Background: A serious complication with drug-eluting coronary stents is late thrombosis, caused by exposed stent struts not covered by endothelial cells in the healing process. Real-time detection of this healing process could guide physicians for more individualized anti-platelet therapy. Here we present work towards developing a sensor to detect this healing process. Sensors on several stent struts could give information about the heterogeneity of healing across the stent.

Methods: A piezoelectric microcantilever was insulated with parylene and demonstrated as an endothelialization detector for incorporation within an active coronary stent. After initial characterization, endothelial cells were plated onto the cantilever surface. After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever. This shift was then detected electrically with an LCR meter. The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications.

Results: A cell density of 1300 cells/mm2 on the cantilever surface is detected.

Conclusions: We have developed a self-actuating, self-sensing device for detecting the presence of endothelial cells on a surface. The device is biocompatible and functions reliably in ionic liquids, making it appropriate for implantable applications. This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation. Anti-platelet therapy can be adjusted in real-time with respect to a patient's level of healing and hemorrhaging risks.

Show MeSH
Related in: MedlinePlus