Pursing of planar elastic pockets

Bouremel, Yann; Madaan, Shivam; Lee, Richard M. H.; Eames, I.; Wojcik, Adam; Khaw, PT

doi:10.1016/j.jfluidstructs.2017.01.018

Cited by 10 publications

(7 citation statements)

References 47 publications

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“…We have also performed studies and developed theoretical models that explain how the appearance of subconjunctival blebs in the early postoperative period may be used to develop clinical grading systems to help improve surgical outcomes following surgery (Bouremel Y, et al IOVS . 2017;58:ARVO E-Abstract 5576) 15. These pressure spikes did not occur in all eyes, and further studies are currently underway to shed more light on why these results were observed.…”

Section: Discussionmentioning

confidence: 88%

The Implications of an Ab Interno Versus Ab Externo Surgical Approach on Outflow Resistance of a Subconjunctival Drainage Device for Intraocular Pressure Control

Lee

Bouremel

Eames³

et al. 2019

Trans. Vis. Sci. Tech.

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Purpose Minimally invasive glaucoma surgery (MIGS) devices that drain into the subconjunctival space can be inserted via an ab externo or ab interno approach. Limited experimental data exists as to the impact of either technique on intraocular pressure (IOP) control. We performed microfluidic studies by using ex vivo rabbit eyes to assess the effect of each approach on outflow resistance of a subconjunctival drainage device for IOP control. Methods A microfluidic experiment system was designed, consisting of a controlled reservoir of water connected to a pressure pump/flow sensor. The flow rate of water was fixed at 2 μl/min to simulate aqueous humor production. The pressure readings for each approach were recorded at a frequency of 1 Hz. A baseline reading was made before tube insertion into the eye (PEEK tube length set to aim for an initial outflow resistance of 5 to 10 mm Hg/μL/min) followed by measurements for a cumulative 2-ml volume entering the subconjunctival space. Results were adjusted for water viscosity at 37°C and reported as outflow resistance (mm Hg/μL/min ± standard error of mean). Results Outflow resistance via the ab interno approach was 90.4% higher than with the ab externo approach being measured at 0.80 ± 0.11 mm Hg/μL/min and 0.42 ± 0.05 mm Hg/μL/min, respectively. Bleb formation was observed to be less predictable with the ab interno approach. Conclusions The ab interno approach demonstrated greater outflow resistance and less predictable bleb formation than the ab externo approach. These results have implications for long-term IOP control and success depending on the approach to device insertion and could be an important consideration for future MIGS devices. Translational Relevance The effect of the ab interno versus ab externo approach of a MIGS device inserted into the subconjunctival space was assessed. The ab interno approach demonstrated greater outflow resistance and less predictable bleb formation that may have implications for the development of future MIGS devices.

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Section: Discussionmentioning

confidence: 88%

The Implications of an Ab Interno Versus Ab Externo Surgical Approach on Outflow Resistance of a Subconjunctival Drainage Device for Intraocular Pressure Control

Lee

Bouremel

Eames³

et al. 2019

Trans. Vis. Sci. Tech.

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“…Full numerical calculations confirm that the above model is good when λ 0 ≤ 1.1 (Bouremel et al, 2017), beyond which the analysis breaks down since the increase of λ 1 withr needs to be taken into account. When the pocket is compressed, within the contact region λ 1 = λ 2 = λ c are constants, while outside the contact-region, we approximate the stretch factors as…”

Section: Analytical Modelmentioning

confidence: 70%

“…The material properties were characterised using an electromagnetic linear actuator (Bose Electroforce 3220 Series III to determine C 1 , C 2 and E). The experimental procedure is described in Bouremel et al (2017) and the samples used are different. The Mooney-Rivlin parameters of the silicone sheets are listed in Table 1.…”

Section: Materials Characterisationmentioning

confidence: 99%

Compression of pressurised elastic pockets

Bouremel

Eames

Madaan

et al. 2018

International Journal of Non-Linear Mechanics

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A circular silicone sheet is clamped at its edge and pressurised by the injection of a liquid beneath creating a pocket. We study experimentally the deformation and pressure increase caused by the compression of a pressurised pocket. Excellent agreement is found between experimental observations and numerical predictions based on an axisymmetric thin hyperelastic material; an approximate analytical model explains the link between changes in shape and the applied force.

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“…The transition between the two regimes [Eqs. (1b) and (1c)] occurs in the relative pressure range Δp=p e ¼ 5-10, see [42].…”

Section: =3mentioning

confidence: 99%

Bending and Stretching of Soft Pores Enable Passive Control of Fluid Flows

2020

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Programmable valves and actuators are widely used in man-made systems to provide sophisticated control of fluid flows. In nature, however, this process is frequently achieved using passive soft materials. Here we study how elastic deformations of cylindrical pores embedded in a flexible membrane enable passive flow control. We develop biomimetic valves with variable pore radius, membrane radius, and thickness. Our experiments reveal a mechanism where small deformations bend the membrane and constrict the pore-thus reducing flow-while larger deformations stretch the membrane, expand the pore, and enhance flow. We develop a theory capturing this highly nonmonotonic behavior, and validate the scaling across a broad range of material and geometric parameters. Our results suggest that intercompartmental flow control in living systems can be encoded entirely in the physical attributes of soft materials. Moreover, this design could enable autonomous flow control in man-made systems.

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Pursing of planar elastic pockets

Cited by 10 publications

References 47 publications

The Implications of an Ab Interno Versus Ab Externo Surgical Approach on Outflow Resistance of a Subconjunctival Drainage Device for Intraocular Pressure Control

The Implications of an Ab Interno Versus Ab Externo Surgical Approach on Outflow Resistance of a Subconjunctival Drainage Device for Intraocular Pressure Control

Compression of pressurised elastic pockets

Bending and Stretching of Soft Pores Enable Passive Control of Fluid Flows

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