Details
| Original language | English |
|---|---|
| Pages (from-to) | 907-920 |
| Number of pages | 14 |
| Journal | Biomedical microdevices |
| Volume | 14 |
| Issue number | 5 |
| Publication status | Published - 19 Jun 2012 |
| Externally published | Yes |
Abstract
This paper describes methods for design, manufacturing and characterization of a micro-mechanical valve for a novel glaucoma implant. The implant is designed to drain aqueous humour from the anterior chamber of the eye into the suprachoroidal space in case of an elevated intraocular pressure (IOP). In contrast to any existing glaucoma drainage device (GDD), the valve mechanism is located in the anterior chamber and there, surrounded by aqueous humour, immune to fibrosis induced failure. For the prevention of hypotony the micro-mechanical valve is designed to open if the physiological pressure difference between the anterior chamber and the suprachoroidal space in the range of 0.8 mmHg to 3.7 mmHg is exceeded. In particular the work includes: (i) manufacturing and morphological characterization of polymer tubing, (ii) mechanical material testing as basis for (iii) the design of micro-mechanical valves using finite element analysis (FEA), (iv) manufacturing of microstent prototypes including micro-mechanical valves by femtosecond laser micromachining and (v) the experimental fluid-mechanical characterization of the manufactured microstent prototypes with regard to valve opening pressure. The considered materials polyurethane (PUR) and silicone (SIL) exhibit low elastic modulus and high extensibility. The unique valve design enables a low opening pressure of micro-mechanical valves. An ideal valve design for PUR and SIL with an experimentally determined opening pressure of 2 mmHg and 3.7 mmHg is identified. The presented valve approach is suitable for the inhibition of hypotony as a major limitation of today's GDD and will potentially improve the minimally invasive treatment of glaucoma.
Keywords
- Femtosecond laser micromachining, Finite element analysis of microvalve, Glaucoma drainage device, Microfluidics, Suprachoroidal space
ASJC Scopus subject areas
- Engineering(all)
- Biomedical Engineering
- Biochemistry, Genetics and Molecular Biology(all)
- Molecular Biology
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In: Biomedical microdevices, Vol. 14, No. 5, 19.06.2012, p. 907-920.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Development of a micro-mechanical valve in a novel glaucoma implant
AU - Siewert, Stefan
AU - Schultze, Christine
AU - Schmidt, Wolfram
AU - Hinze, Ulf
AU - Chichkov, Boris
AU - Wree, Andreas
AU - Sternberg, Katrin
AU - Allemann, Reto
AU - Guthoff, Rudolf
AU - Schmitz, Klaus Peter
N1 - Funding information: Acknowledgement This work is supported by the German Research Foundation (DFG) as a part of the Special Research Program Trans-regio 37 “Micro-and Nanosystems in Medicine – Reconstruction of Biological Functions”.
PY - 2012/6/19
Y1 - 2012/6/19
N2 - This paper describes methods for design, manufacturing and characterization of a micro-mechanical valve for a novel glaucoma implant. The implant is designed to drain aqueous humour from the anterior chamber of the eye into the suprachoroidal space in case of an elevated intraocular pressure (IOP). In contrast to any existing glaucoma drainage device (GDD), the valve mechanism is located in the anterior chamber and there, surrounded by aqueous humour, immune to fibrosis induced failure. For the prevention of hypotony the micro-mechanical valve is designed to open if the physiological pressure difference between the anterior chamber and the suprachoroidal space in the range of 0.8 mmHg to 3.7 mmHg is exceeded. In particular the work includes: (i) manufacturing and morphological characterization of polymer tubing, (ii) mechanical material testing as basis for (iii) the design of micro-mechanical valves using finite element analysis (FEA), (iv) manufacturing of microstent prototypes including micro-mechanical valves by femtosecond laser micromachining and (v) the experimental fluid-mechanical characterization of the manufactured microstent prototypes with regard to valve opening pressure. The considered materials polyurethane (PUR) and silicone (SIL) exhibit low elastic modulus and high extensibility. The unique valve design enables a low opening pressure of micro-mechanical valves. An ideal valve design for PUR and SIL with an experimentally determined opening pressure of 2 mmHg and 3.7 mmHg is identified. The presented valve approach is suitable for the inhibition of hypotony as a major limitation of today's GDD and will potentially improve the minimally invasive treatment of glaucoma.
AB - This paper describes methods for design, manufacturing and characterization of a micro-mechanical valve for a novel glaucoma implant. The implant is designed to drain aqueous humour from the anterior chamber of the eye into the suprachoroidal space in case of an elevated intraocular pressure (IOP). In contrast to any existing glaucoma drainage device (GDD), the valve mechanism is located in the anterior chamber and there, surrounded by aqueous humour, immune to fibrosis induced failure. For the prevention of hypotony the micro-mechanical valve is designed to open if the physiological pressure difference between the anterior chamber and the suprachoroidal space in the range of 0.8 mmHg to 3.7 mmHg is exceeded. In particular the work includes: (i) manufacturing and morphological characterization of polymer tubing, (ii) mechanical material testing as basis for (iii) the design of micro-mechanical valves using finite element analysis (FEA), (iv) manufacturing of microstent prototypes including micro-mechanical valves by femtosecond laser micromachining and (v) the experimental fluid-mechanical characterization of the manufactured microstent prototypes with regard to valve opening pressure. The considered materials polyurethane (PUR) and silicone (SIL) exhibit low elastic modulus and high extensibility. The unique valve design enables a low opening pressure of micro-mechanical valves. An ideal valve design for PUR and SIL with an experimentally determined opening pressure of 2 mmHg and 3.7 mmHg is identified. The presented valve approach is suitable for the inhibition of hypotony as a major limitation of today's GDD and will potentially improve the minimally invasive treatment of glaucoma.
KW - Femtosecond laser micromachining
KW - Finite element analysis of microvalve
KW - Glaucoma drainage device
KW - Microfluidics
KW - Suprachoroidal space
UR - http://www.scopus.com/inward/record.url?scp=84870300773&partnerID=8YFLogxK
U2 - 10.1007/s10544-012-9670-7
DO - 10.1007/s10544-012-9670-7
M3 - Article
C2 - 22711457
AN - SCOPUS:84870300773
VL - 14
SP - 907
EP - 920
JO - Biomedical microdevices
JF - Biomedical microdevices
SN - 1387-2176
IS - 5
ER -