Rheology of Granular Material
- Flows and Dynamics of Granular Materials
- Flow Instabilities in Particulate Systems
- Solid/liquid Separation Particle Technology
Drug Delivery Systems
- Transport Modeling for Drug Delivery in Brain, Liver and Bone Tumors
- Controlled Release Devices
- Chemotherapy & Radiotherapy Applications
- 3D Printing for Wound Healing Applications
Biomass Gasification for Clean Energy
- CFD Modeling for gasification process
- Design of novel gasifier and gasification process
- Developing valuable products from gasification process
- Conversion of Waste to Resource
Particle Technology – Flow and Dynamics of Granular Materials
Pneumatic conveying of granular materials has important applications in the pharmaceutical and food processing industry. It is necessary to monitor the granular flow to avoid choking of the pipe or breakage of the particles. One technique available for non-invasive measurement of solids distribution in pipe is the Electrical Capacitance Tomography (ECT). The ECT is used in several studies for monitoring and characterization of flows of granular materials in pipes and around bends.
Temporal evolution of the dominant density wave in a gravity-driven channel flow of granular materials: Distribution of solid fraction.
Visualization of a slugging flow of polypropylene in a vertical riser
(a) Snapshot from a high speed digital camera
(b) ECT images at regular time interval showing the passage of a slug
(c) Time-averaged particle concentration contours
Visualization and corresponding velocity profile (captured by PIV) of granular materials undergoing vertical vibrations
Other instruments also used in our investigation of flow behaviors of granular materials include laser techniques such as Phase-Doppler Particle Analyzer (PDPA) and Particle Image Velocimetry (PIV). Besides the experimental and theoretical work on the flow characterization and profiles of granular materials, much work was also carried out on the investigation of the instabilities of granular material in various flow modes. One of the highlights of this research is in the study of granular materials in a vertically vibrating bed. The driving factors causing the instabilities in the system and the mechanism of these instabilities were investigated through experiments and numerical simulation. Other interesting aspects of this research field includes the investigation of the effects of electrostatics on the flow of particles in pipes.
Drug Delivery Systems – Fabrication of Drug Delivery Devices
Controlled release systems using drug-loaded polymeric microparticles are widely studied in drug delivery research due to their advantages over conventional methods of drug administration. Conventional drug administration methods are usually accompanied by problems such as high dosage required leading to toxicity problems and other side effects. Most of these problems are resolved when polymeric micro-carriers are used for drug delivery. In the past years, our group has carried out much research on the fabrication of drug encapsulated microspheres using different polymers such as PLA, PLGA, PCL etc.
SEM pictures of Taxol loaded PCL microspheres fabricated using EHDA (a) Overall view showing nearly monodispersity
(b) Close-up on single microsphere illustrating the morphology
SEM pictures of double-walled PLLA-PLGA microspheres fabricated using modified oil-in-oil-in-water (O/O/W) emulsion solvent evaporation technique, (a) Etanidazole loaded microsphere; (b) unloaded microsphere
The common methods used in fabrication of the drug delivery devices include single emulsion, double emulsion and spray drying. Besides these conventional methods, we also look into alternative fabrication methods such as using the ElectroHydroDynamic Atomizer (EHDA). This method is found to produce PCL microspheres with high monodispersity and good spherical morphology. Our research efforts in this field include characterization and modification of the properties of the microparticles fabricated. Drug encapsulation efficiency and in vitro release studies were carried out for the drug carriers produced. In vivo experiments and animal tests were also conducted to study the efficacy and characteristics of the drug delivery devices fabricated.
CLSM images of Glioma C6 (brain tumor) cells after incubation with coumarin-6 loaded PCL microparticles
Biomass gasification – Cogasification of Sewage Sludge and Biomass for Clean Energy Application
GASIFICATION, which solid wastes can be converted to quality syngas containing H2 and CO which can be directly burnt to produce electricity, provides an attractive alternative process to incineration as it can prevent the aforesaid problems of incineration. Gasification and/or co-gasification of several solid wastes including woody biomass, sewage sludge which was collected from the wastewater treatment plant in Singapore, food wastes and so on have been performed. Moreover, the solid residues from the gasification system has been further refined into highly-valued products, for example, catalysts for biodiesel production. Last but not least, the environmental and health effects of our gasification system have been closely monitored to ensure that our developed system is clean and environmental friendly.
