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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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Related in: MedlinePlus

Veeco active probe. Cantilever consists of a Si substrate (thickness = 4 μm) supporting a ZnO stack (0.25 μm Ti/Au, 3.5 μm ZnO, and 0.25 μm Ti/Au). Other relevant dimensions are shown in microns.
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Figure 1: Veeco active probe. Cantilever consists of a Si substrate (thickness = 4 μm) supporting a ZnO stack (0.25 μm Ti/Au, 3.5 μm ZnO, and 0.25 μm Ti/Au). Other relevant dimensions are shown in microns.

Mentions: Post-mortem analysis indicates that the most powerful histological predictor for late stent thrombosis is endothelial coverage, specifically, the ratio of covered to uncovered stent struts [6]. A stent that actively monitors endothelial coverage would allow physicians to better individualize a patient's anti-platelet therapy based on their clotting risk. Embedding these sensors along several struts in a stent would give detailed information regarding the level of healing in an individual patient. This article presents the development of such a sensor that consists of a commercially available piezoelectric cantilever (DMASP, Veeco Probes), which has a film of zinc oxide used to actuate the cantilever in AFM imaging applications (Figure 1). Micromachined cantilevers lend themselves well to numerous sensing applications. Attachment of molecules or whole cells onto the cantilever surface alters the effective mass and surface stress of the cantilever, and causes a shift in the cantilever's resonance frequency, as has been demonstrated previously as sensors for cell detection [7-11]. Cantilevers with integrated piezoelectric sensing elements do not require alignment of an external laser and are not affected by changes in surface reflectivity or the index of refraction of the operating fluid, allowing a more compact system. We have insulated the cantilever, allowing us to readily detect resonant frequencies in a fluid environment.


Sensor to detect endothelialization on an active coronary stent.

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

Veeco active probe. Cantilever consists of a Si substrate (thickness = 4 μm) supporting a ZnO stack (0.25 μm Ti/Au, 3.5 μm ZnO, and 0.25 μm Ti/Au). Other relevant dimensions are shown in microns.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Veeco active probe. Cantilever consists of a Si substrate (thickness = 4 μm) supporting a ZnO stack (0.25 μm Ti/Au, 3.5 μm ZnO, and 0.25 μm Ti/Au). Other relevant dimensions are shown in microns.
Mentions: Post-mortem analysis indicates that the most powerful histological predictor for late stent thrombosis is endothelial coverage, specifically, the ratio of covered to uncovered stent struts [6]. A stent that actively monitors endothelial coverage would allow physicians to better individualize a patient's anti-platelet therapy based on their clotting risk. Embedding these sensors along several struts in a stent would give detailed information regarding the level of healing in an individual patient. This article presents the development of such a sensor that consists of a commercially available piezoelectric cantilever (DMASP, Veeco Probes), which has a film of zinc oxide used to actuate the cantilever in AFM imaging applications (Figure 1). Micromachined cantilevers lend themselves well to numerous sensing applications. Attachment of molecules or whole cells onto the cantilever surface alters the effective mass and surface stress of the cantilever, and causes a shift in the cantilever's resonance frequency, as has been demonstrated previously as sensors for cell detection [7-11]. Cantilevers with integrated piezoelectric sensing elements do not require alignment of an external laser and are not affected by changes in surface reflectivity or the index of refraction of the operating fluid, allowing a more compact system. We have insulated the cantilever, allowing us to readily detect resonant frequencies in a fluid environment.

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