Dr. Laura A. Poole-Warren Profile

Dr. Laura A. Poole-Warren

at Univ of New South Wales

SPIE Involvement:

Author

Publications (3)

This will count as one of your downloads.

You will have access to both the presentation and article (if available).

DOWNLOAD NOW

This content is available for download via your institution's subscription. To access this item, please sign in to your personal account.

Email or Username Forgot your username?

Password Forgot your password?

Show

Keep me signed in

No SPIE account? Create an account

Proceedings Article | 16 February 2005 Paper

Electrically conductive polyurethanes for biomedical applications

Charles Williams, M. Nash, Laura Poole-Warren

Proceedings Volume 5651, (2005) https://doi.org/10.1117/12.585321

KEYWORDS: Polymers, Polyurethane, Electrodes, Biomedical optics, Carbon nanotubes, Metals, Tissues, Composites, Nanoparticles, Glasses

Read Abstract +

Electrical interfacing with neural tissue poses significant problems due to host response to the material. This response generally leads to fibrous encapsulation and increased impedance across the electrode. In neural electrodes such as cochlear implants, an elastomeric material like silicone is used as an insulator for the metal electrode. This project ultimately aims to produce a polymer electrode with elastomeric mechanical properties, metal like conductivity and capability. The approach taken was to produce a nanocomposite elastomeric material based on polyurethane (PU) and carbon nanotubes. Carbon nanotubes are ideal due to their high aspect ratio as well as being a ballistic conductor. The choice of PU is based on its elastomeric properties, processability and biocompatibility. Multi-walled nanotubes (MWNTs) were dispersed ultrasonically in various dispersive solutions before being added at up to 20wt% to a 5wt% PU (Pellethane80A) in Dimethylacetamide (DMAc). Films were then solvent cast in a vacuum oven overnight. The resulting films were tested for conductivity using a two-probe technique and mechanically tested using an Instron tensiometer. The percolation threshold (p) of the PU/MWNT films occurred at loadings of between 7 and 10 wt% in this polymer system. Conductivity of the films (above p) was comparable to those for similar systems reported in the literature at up to approximately 7x10^-2 Scm^-1. Although PU stiffness increased with increased %loading of nanotubes, all composites were highly flexible and maintained elastomeric properties. From these preliminary results we have demonstrated electrical conductivity. So far it is evident that a superior percolation threshold is dependent on the degree of dispersion of the nanotubes. This has prompted work into investigating other preparations of the films, including melt-processing and electrospinning.

Proceedings Article | 13 July 2004 Paper

Albumin-genipin solder for laser tissue welding

Antonio Lauto, John Foster, Albert Avolio, Laura Poole-Warren

Proceedings Volume 5312, (2004) https://doi.org/10.1117/12.531466

KEYWORDS: Tissues, Laser welding, Laser tissue interaction, Proteins, Solids, Intestine, Interfaces, Semiconductor lasers, Natural surfaces, In vivo imaging

Read Abstract +

Background. Laser tissue soldering (LTS) is an alternative technique to suturing for tissue repair. One of the major drawbacks of LTS is the weak tensile strength of the solder welds when compared to sutures. In this study, the possibility was investigated for a low cytotoxic crosslinker, acting on amino groups, to enhance the bond strength of albumin solders. Materials and Methods. Solder strips were welded onto rectangular sections of sheep small intestine by a diode laser. The laser delivered in continuous mode mode a power of 170 ± 10 mW at λ=808 nm, through a multimode optical fiber (core size = 200 μm) to achieve a dose of 10.8 ± 0.5 J/mg. The solder thickness and surface area were kept constant throughout the experiment (thickness = 0.15 ± 1 mm, area = 12 ± 1.2 mm²). The solder incorporated 62% bovine serum albumin, 0.38% genipin, 0.25% indocyanin green dye (IG) and water. Tissue welding was also performed with a similar solder, which did not incorporate genipin, as a control group. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Results. The tensile strength of the “genipin” solder was twice as high as the strength of the BSA solder (0.21 ± 0.04 N and 0.11 ± 0.04 N respectively; p~10^-15 unpaired t-test, N=30). Discussion. Addition of a chemical crosslinking agent, such as genipin, significantly increased the tensile strength of adhesive-tissue bonds. A proposed mechanism for this enhanced bond strength is the synergistic action of mechanical adhesion with chemical crosslinking by genipin.

Proceedings Article | 12 December 2003 Paper

Low-temperature solder for laser tissue welding

Antonio Lauto, Robert Stewart, D. Felsen, John Foster, Laura Poole-Warren, Dix Poppas

Proceedings Volume 5287, (2003) https://doi.org/10.1117/12.544880

KEYWORDS: Tissues, Laser welding, Interfaces, Laser tissue interaction, Infrared radiation, Infrared imaging, Temperature metrology, Solids, Intestine, Natural surfaces

Read Abstract +

In this study, a two layer (TL) solid solder was developed with a fixed thickness to minimize the difference in temperature across the solder (ΔT) and to weld at low temperature. Solder strips comprising two layers (65% albumin, 35% water) were welded onto rectangular sections of dog small intestine by a diode laser (λ = 808 nm). The laser delivered a power of 170 ± 10 mW through an optical fiber (spot size approximately 1 mm) for 100 seconds. A solder layer incorporated also a dye (carbon black, 0.25%) to absorb the laser radiation. A thermocouple and an infrared thermometer system recorded the temperatures at the tissue interface and at the external solder surface, during welding. The repaired tissue was tested for tensile strength by a calibrated tensiometer. The TL strips were able to minimize ΔT (12 ± 4°C) and control the temperature at tissue-interface. The strips fused on tissue at 55≤T≤62°C had higher tensile strength than the strips soldered at 51≤T<55°C (19.1 ± 6.6 versus 13.1 ± 6.4 gmf). The solid solder could efficiently weld at 60°C as it became insoluble and formed stable bonds with tissue. Fluid albumin solders, by contrast, requires temperatures ≥70°C for tissue repair, which cause more irreversible thermal damage.

My Library

You currently do not have any folders to save your paper to! Create a new folder below.

Folder Name

Folder Description

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks. You are receiving this notice because your organization may not have SPIE eBooks access.*

*Shibboleth/Open Athens users─please sign in to access your institution's subscriptions.

To obtain this item, you may purchase the complete book in print or electronic format on SPIE.org.

ORGANIZATIONAL
Sign in with credentials provided by your organization.

Organizational Username

Organizational Password

Show/Hide Password

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members:

Non-members: ADD TO CART

Keywords/Phrases

Search In:

Publication Years