Jan Bernd Vorstius

Quantitative evaluation of degenerated tendon model using combined optical coherence elastography and acoustic radiation force method

Abstract. Damage of collagen fibers in tendons is often directly related to changes in a tendon’s mechanical properties. Direct quantitative elasticity measurement of tendons will provide important information in tendon dysfunction diagnosis and treatment assessment. A feasibility study of quantifying the mechanical properties of a degenerated tendon model by a nondestructive imaging modality, which combines optical coherence elastography and acoustic radiation force (ARF) method, is presented. The degenerated tendon model was produced by the partial degradation of chicken tendons through incubation with collagenase at different concentrations and incubation times. A 30-kHz longitudinal ultrasound transducer was used to provide an ARF signal, which was detected by an ultra-high sensitive phase sensitive optical coherence tomography (PhS-OCT) system. The experimental results demonstrate that the combination of ARF method and PhS-OCT can measure the elasticity of tendon quantitatively. The corresponding changes in tendon elasticity due to the application of collagenase have been revealed by this new imaging modality. This method can potentially be used in the assessment of tissue engineering products and in the diagnosis and treatment progression of tendon diseases.

The Development of a Combined Electrical & Mechanical Stimulation Bioreactor to Improve Tissue Engineered Muscle Function

This paper describes the development of novel bioreactor systems for use in studying the development of tissue engineered muscle constructs. The bioreactor systems combine two environmental stimuli, mechanical loading and electrical pulses which, independently, are known to promote muscle tissue growth, into a single system to investigate whether further functional improvements can be achieved. The bioreactors are reprogrammable to enable different stimulation protocols to be assessed and allow the simultaneous stimulation of up to six tissues in a single system. This allows us to improve experimental throughput and speeds up our understanding of the physiological processes involved in skeletal muscle development.

A Prototype Therapeutic Capsule Endoscope for Ultrasound-mediated Targeted Drug Delivery

The prevalence of gastrointestinal (GI) diseases such as Crohn’s disease, which is chronic and incurable, are increasing worldwide. Treatment often involves potent drugs with unwanted side effects. The technological–pharmacological combination of capsule endoscopy with ultrasound-mediated targeted drug delivery (UmTDD) described in this paper carries new potential for treatment of these diseases throughout the GI tract. We describe a proof-of-concept UmTDD capsule and present preliminary results to demonstrate its promise as an autonomous tool to treat GI diseases.

Soluble Gas Tight Capsules for use in Surgical Quality Testing

During many surgical procedures such as gastrointestinal or vascular surgery it is necessary to excise and reconnect bodily conduits. Failed connections can have extremely serious consequences and a method to help surgeons determine the integrity of connections has been proposed. This involves the detection of trace gas breaching an anastomosis. A key feature of this is establishing a method to place a controlled volume of gas into the conduit. A soluble capsule method is presented here. The requirements were that the capsule must be safe, a volume of 0.5 − 1.0ml of gas at 2 Bar pressure should be contained, that the filling gas can be varied to suit the clinical application and that the capsules have a shelf life of at least 5 days without showing loss of gas. A device and procedure were developed to meet these criteria. This consists of modified oral pharmaceutical capsules and a capsule filling mechanism contained in a vacuum chamber. Sealing the capsules has been achieved via an alcohol / water mix coupled to capilliary action. Results show performance which meets the design specification and the capsules have shown themselves effective in tests using phantom scenarios.

A hydraulically driven colonoscope

BackgroundConventional colonoscopy requires a high degree of operator skill and is often painful for the patient. We present a preliminary feasibility study of an alternative approach where a self-propelled colonoscope is hydraulically driven through the colon.MethodsA hydraulic colonoscope which could be controlled manually or automatically was developed and assessed in a test bed modelled on the anatomy of the human colon. A conventional colonoscope was used by an experienced colonoscopist in the same test bed for comparison. Pressures and forces on the colon were measured during the test.ResultsThe hydraulic colonoscope was able to successfully advance through the test bed in a comparable time to the conventional colonoscope. The hydraulic colonoscope reduces measured loads on artificial mesenteries, but increases intraluminal pressure compared to the colonoscope. Both manual and automatically controlled modes were able to successfully advance the hydraulic colonoscope through the colon. However, the automatic controller mode required lower pressures than manual control, but took longer to reach the caecum.ConclusionsThe hydraulic colonoscope appears to be a viable device for further development as forces and pressures observed during use are comparable to those used in current clinical practice.

Using an infra-red sensor to measure the dynamic behaviour of N2O gas escaping through different sized holes

An anastomosis is a surgical procedure that consists of the re-connection of two parts of an organ and is commonly required in cases of colorectal cancer. Approximately 80% of the patients diagnosed with this problem require surgery. The malignant tissue located on the gastrointestinal track must be resected and the most common procedure adopted is the anastomosis. Studies made with 2,980 patients that had this procedure, show that the leakage through the anastomosis was 5.1%. This paper discusses the dynamic behavior of N2O gas through different sized leakages as detected by an Infra-Red gas sensor and how the sensors response time changes depending on the leakage size. Different sized holes were made in the rigid tube to simulate an anastomostic leakage. N2O gas was injected into the tube through a pipe and the leakage rate measured by the infra-red gas sensor. Tests were also made experimentally also using a CFD (Computational Fluid Dynamics) package called FloWorks. The results will be compared and discussed in this paper.

Novel modular and perfused bioreactor for tissue engineering

The current design of perfused bioreactors and bio-incubators tend to be complex and are purpose built for the specific needs of one research underway. Modifications or the ability to change the environment and stimulation parameters are costly in time or involve the complete redesign of the system. The following project describes the development of a modular bio-incubator that allows the control and adjustment of the cell culture environment whilst monitoring the cell behaviour in realtime.)

Bio-mechanical analysis for characterising a commercial 3D printed composite

The aim of this research was to mechanically and biologically characterise a relatively new composite material, which enabled the monitoring of the materials performance within a bio-mechanical context for future application. This paper investigates the bio-mechanical properties of a commercial composite, printed using a rapid prototyper. The printed infiltrated samples were also examined for cytotoxic effects when in solution with fibroblast cells. This research paper demonstrated that the density of the commercial composite and compressive strength closely mimic that of cancellous bone. Unhardened samples exhibited a compressive strength of up to 6.5 MPa. The introduction of open pore cells exhibited a compressive strength range between 0.383–5.15 MPa, and behaved in a manner similar to other ceramic composites. The investigation of the 3D printed samples allowed us to evaluate the mechanical properties of the material as well as the biocompatibility of the infiltration techniques employed.

Thermal imaging analysis of 3D biological agarose matrices

Advances in rapid prototyping have allowed for the construction of biocompatible materials (hydrogels) to be used in regenerative medicine. Within this area of construction inherent problems arise due to the mechanical instability of such materials that are temperature dependent. This research paper describes a thermal imaging analysis used to circumvent needle blockage when using an RP technology called bioplotting, used for extruding high temperature hydrogels, where agarose was the experimental biomaterial. The investigation describes how we have overcome these inherent problems through thermal imaging analysis, allowing us to accurately construct 3D biological matrices that have satisfied the in-vitro cell requirements for producing artificial tissue scaffolds. By properly insulating the needle and chamber, we have reduced the time taken for the needle to reach a sufficient plotting temperature. The analysis has allowed us to produce 3D biological matrices that have satisfied the in vitro cell requirements for producing artificial tissue. The analysis reported in this paper has opened the possibility for other high temperature dependent hydrogels to be constructed into 3D biological matrices without delay.

Bio-Mechanical Evaluation of a 3D Printed Composite Material

Composite materials such as ceramic are now widely used in the field of Tissue Engineering. Ceramic composites are used because of their high compressive strength, microstructure and biocompatibility. This paper describes the mechanical and biological characterisation of a commercial composite material. The material was formed into a 3D scaffold for use in cell studies using Rapid Prototyping. Secondary hardening phases (sintering and infiltration) were used in an aim to increase the compressive strength and the surface integrity of the printed samples. This resulted in increases up to 12MPa when compared with untreated samples at 4MPa. The infiltrated samples were monitored for any cytotoxic effects while in solution with Primary Tendon Fibroblasts. Both infiltration techniques resulted in early cell mortality indicating the presence of non-biocompatible substances. This research paper evaluates the mechanical properties and biocompatibility of the Rapid Prototyped material.