Dr. Zemp’s research interest primarily involve novel methods of biomedical imaging, including biomedical optics and biomedical ultrasound. These new technologies aim to provide information to clinicians and biologists that are presently difficult to obtain with other imaging techniques. He is also interested in technologies for improved drug and gene delivery, and disease diagnosis using biomarkers and ultrasound. His research encompasses system design, physical modeling, micro- and nano-fabrication methods, optics and laser systems, ultrasound hardware and software development, image and signal processing and analysis, molecular biology-based methods, and nanotechnology.
- Micro-Electromechanical Systems: We are building Capacitive Micromachined Ultrasound Transducers (CMUTs) using microfabrication technology. These next-generation ultrasound devices promise improved performance and system portability, and 3D imaging. This work involves design, modeling, fabrication, and testing. Sub-projects include architectures for minimal dielectric charging and improved electrical safety, architectures for optimized transmitters and receivers, architecture for 2D arrays for 3D ultrasound imaging, and transducers for combined imaging and therapy.
- Biomedical Photoacoustics: Photoacoustic imaging involves firing a pulsed laser into the body. Absorbed optical energy induces a thermo-elastic expansion launching acoustic waves, which are received and reconstructed to form high-resolution images with optical-absorption contrast. These high-resolution optical-contrast images promise new frontiers in molecular and functional imaging. Sub-projects include imaging of hemoglobin oxygen saturation, imaging of oxygen consumption, imaging of gene expression, imaging of tumor angiogenesis, imaging of nanoparticle contrast agents, realtime systems to image to depths of multiple centimetres in tissue, or down to micron-scale resolution to resolve capillary networks.
- Biomarker amplification and localization using ultrasound: Blood biomarkers are useful in disease detection and diagnosis. However, they are often present in low concentrations and give no information about the location of a disease. We are investigating how ultrasound may be used to locally release biomarkers, serving to amplify biomarker levels, as well as localize the location of the ultrasound-liberated biomarkers.
- Lipid-stablized microbubble liposomes for ultrasound-triggered drug and gene delivery: Often chemotherapies are ineffective due to drug resistance. Additionally many chemotherapies have side effects due to non-local delivery. Ultrasound can pop microbubbles loaded with drugs or genes to locally release the therapeutics, and locally enhance delivery. We are focusing on applications to pancreatic and breast cancer, improving chemotherapeutic efficacy, and designing ultrasound technology for both imaging and therapy
- Multiplexed molecular imaging using Surface-Enhanced Raman-Scattering (SERS) nanoparticles: Present approaches to in vivo molecular imaging suffer from the limitation that the bio-distribution of only one (sometimes two or three in the case of fluorescence microscopy) molecular species can be imaged at a time. Biologists want to see complex biochemical pathways in action in vivo. SERS nanoparticles may provide a solution. They scatter incident light inelastically with a spectral signature that can be used as a kind of bar-code or fingerprint that can be used to quantify the concentration of each species of these particles out of a mixture via spectral de-mixing. While Raman scattering is very weak, metallic nanoparticles have been shown to enhance Raman scattered light by 14 orders of magnitude. We are developing tomographic pre-clinical imaging solutions leveraging SERS nanoparticles as potential targetable contrast agents.
- Methods for very high-frame-rate ultrasound imaging of heart valves and application to non-invasive assessment of pulmonary hypertension: We have a unique ultrasound platform with considerable engineering flexibility. We are developing methods to image at many thousands of frames per second. We will be applying these methods to studying heart valve dynamics in clinical conditions such as pulmonary hypertension.