Biomedical subjects

Dudley S Finch

Publications and source records attributed to Dudley S Finch.

4 recordsLinked to original sources

PubMed2007

A uniaxial bioMEMS device for quantitative force-displacement measurements.

There is a need for experimental techniques that allow the simultaneous imaging of cellular cystoskeletal components with quantitative force measurements on single cells. A bioMEMS device has been developed for the application of strain to a single cell while simultaneously quantifying its force response. The prototype device presented here allows the mechanical study of a single, adherent cell in vitro. The device works in a fashion similar to a displacement-controlled uniaxial tensile machine. The device is calibrated using an AFM cantilever and shows excellent agreement with the calculated spring constant. The device is demonstrated on a single fibroblast. The force response of the cell is seen to be linear until the onset of de-adhesion with the de-adhesion from the cell platform occurring at a force of approximately 1500 nN.

Animals↗

PubMed2006

Toward a self-deploying shape memory polymer neuronal electrode.

The widespread application of neuronal probes for chronic recording of brain activity and functional stimulation has been slow to develop partially due to long-term biocompatibility problems with existing metallic and ceramic probes and the tissue damage caused during probe insertion. Stiff probes are easily inserted into soft brain tissue but cause astrocytic scars that become insulating sheaths between electrodes and neurons. In this communication, we explore the feasibility of a new approach to the composition and implantation of chronic electrode arrays. We demonstrate that softer polymer-based probes can be inserted into the olfactory bulb of a mouse and that slow insertion of the probes reduces astrocytic scarring. We further present the development of a micromachined shape memory polymer probe, which provides a vehicle to self-deploy an electrode at suitably slow rates and which can provide sufficient force to penetrate the brain. The deployment rate and composition of shape memory polymer probes can be tailored by polymer chemistry and actuator design. We conclude that it is feasible to fabricate shape memory polymer-based electrodes that would slowly self-implant compliant conductors into the brain, and both decrease initial trauma resulting from implantation and enhance long-term biocompatibility for long-term neuronal measurement and stimulation.

Algorithms↗

PubMed2005

Analysis and evaluation of a biomedical polycarbonate urethane tested in an in vitro study and an ovine arthroplasty model. Part II: in vivo investigation.

The polyurethane (PU) elastomer Corethane 80A (Corvita) is being considered as the acetabular bearing material in a novel total replacement hip joint. Its biostability was investigated in vitro (Analysis and evaluation of a biomedical polycarbonate urethane tested in an in vitro study and an ovine arthroplasty model. Part I: material selection and evaluation, Biomaterials, in press) together with three other commercially available biomedical PUs: Pellethane 2363-80A (DOW Chemical), a polyhexamethylene oxide based PU, PHMO-PU (CSIRO, not supplied as a commercial product) and ChronoFlex AL-80A (CardioTech). From the in vitro studies, Corethane 80A displayed the best overall resistance to hydrolysis, ESC, MIO and calcification, followed by ChronoFlex 80A and PHMO-PU, with Pellethane 80A being the least stable. Building on the in vitro investigation, the follow-up in vivo study (reported here) assessed Corethane 80A as the bearing layer in a prototype compliant layer acetabular cup, in a fully functioning ovine total hip arthoplasty (THA) model. PU degradation in the retrieved cups was analysed using a range of analytical and physical-testing methods including mechanical testing, differential scanning calorimetry, Fourier transform infrared spectroscopy and environmental scanning electron microscopy. The Corethane 80A functioned well in the THA model, with the bearing surfaces of the retrieved hip cups showing no significant evidence of biodegradation or wear damage after 3 years in vivo. The findings in this study provide compelling evidence for the biostability and effectiveness of acetabular cups incorporating a Corethane 80A compliant bearing layer.

Absorptiometry, Photon↗

PubMed2005

Analysis and evaluation of a biomedical polycarbonate urethane tested in an in vitro study and an ovine arthroplasty model. Part I: materials selection and evaluation.

The polyurethane elastomer (PU) Corethane 80A (Corvita) is being considered as the acetabular bearing material in a novel total replacement hip joint. The biostability of Corethane 80A was investigated in vitro (this work) and in vivo (reported separately) in a fully functioning ovine total hip arthroplasty (THA) model, with the PU as the bearing layer in a prototype compliant layer acetabular cup. The in vitro studies assessed the resistance of Corethane 80A to the main degradation mechanisms observed in PUs: hydrolysis, environmental stress cracking (ESC), metal ion oxidation (MIO) and calcification. The performance of the polycarbonate PU Corethane 80A was assessed alongside three other commercially available biomedical PUs: polyether PUs Pellethane 2363-80A (DOW Chemical) and PHMO-PU (CSIRO, not supplied as a commercial material) as well as polycarbonate PU ChronoFlex AL-80A (CardioTech). Chemical and structural variables that affect the properties of the materials were analysed with particular attention to the nature of the material's hard and soft segments. PU degradation was probed using a range of analytical tools and physical-testing methods, including mechanical testing, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and environmental scanning microscopy (ESEM). Corethane 80A displayed the best overall resistance to hydrolysis, ESC, MIO and calcification, followed by ChronoFlex 80A and PHMO-PU. Pellethane 80A was the least stable. This study provides compelling evidence for the biostability and effectiveness of Corethane 80A and points to its suitability for use as a compliant bearing layer in hip arthroplasty, and possibly also other joints.

Arthroplasty, Replacement, Hip↗