Monolithic integration of light sources and detectors allow for flexible, miniature, low-cost biosensors. We develop GaAs-based Vertical Cavity Surface Emitting Lasers (VCSELs) and PIN photodiodes on a single substrate as a miniature readout module for optical biosensing. These biosensors can be optimized for several sensing modalities including fluorescence, back-scattering and index-of-refraction sensing.
Label-free biosensing approaches permit rapid real-time detection, and minimize sample preparation and interference with the detected analyte. We use index-of-refraction sensing in photonic nano-structures as a label-free approach for biosensing. In applications of in vitro diagnostics, sensing with photonic crystal nanostructures provides the benefits of high sensitivity, speed, portability and accuracy. A photonic crystal slab (PCS) is a periodic dielectric nanostructure that can affect the behaviour of light at interfaces through guided resonance modes. At a guided resonance frequency, a high field concentration associates with the PCS, allowing for adjacent biomolecules to be sensed via changes in local index of refraction.
Optical imaging of neural activity and cortical hemodynamics allow for a minimally invasive interrogation of the brain. Changes in neural activity and blood flow can be observed by imaging the cortex and evaluating changes in back-reflected light. We develop optical imaging techniques and sensor arrays for optical neural imaging that incorporate our miniature semiconductor biosensors. Our goal is to enable implantable, minimally invasive optical recording of neural activity in freely-behaving subjects.
Implantable sensors allow for continuous monitoring of tissue dynamics and can be applied to tracking changes in tumour growth or therapy and stem cell development, among other applications. We develop miniature implantable optical biosensors that incorporate our semiconductor biosensors and evaluate their performance in fluorescence sensing of optical molecular markers that report tissue dynamics.
Our research interests include developing biomedical imaging systems and optical bio-sensors based on semiconductor devices and nano-structures, and their application to bio-medical diagnostics, in vivo imaging, and study of bio-molecular interactions. The goal of our work is to integrate sensor components into miniature functional bio-sensors and apply them to novel biology and bio-medical applications. As such, our research is interdisciplinary and include semiconductor device physics, optics, micro- and nano-fabrication, chemistry and applications in biomedical diagnostics, cancer studies and neurobiology.