Research

 The overarching theme of our research is the development of new micro-optical platform technologies and applying them to address contemporary challenges in biomedical and life-science imaging. At the core of these platform technologies is always a novel tunable micro-optical component. We dedicate considerable time to the design, manufacturing, packaging and characterization of a wide variety of optical microsystems, including micromirror arrays, tunable diffractive and aspherical refractive elements, deformable phase plates and ultra-miniaturized laser scanners. In addition to the complete arsenal of standard silicon micromachining, we also employ numerous novel manufacturing techniques for the realization of these components. Of particular recent interest of ours have been the use of optofluidics, and advanced 3D micro- and nano-printing techniques to attain more freedom in the component design and functionality. Thanks to this freedom, we have advanced two particularly versatile platforms that expanded our research into its two current foci:

Multi-modal endomicroscopy for point-of-care diagnosis

Optical biopsy refers to a collection of endoscopic imaging techniques that allow cellular-level histopathological observations to be performed on site, without tissue removal. Numerous techniques, such as endocytoscopy and fluorescence imaging, have already found their way into the clinical use over the last years; others, such as confocal laser endomicroscopy, Raman spectroscopy or optical coherence tomography (OCT), are expected to enter routine clinical use in the imminent future. Regardless of the target pathology, however, these optical methods are yet to attain the selectivity and specificity of traditional biopsy. This is why multi-modal imaging, which can provide complete tissue characterization through complementary modalities, is the key to the success of optical biopsy. Different imaging techniques rely on vastly different optics, and integrating them within an ultra-miniaturized probe is a substantial challenge that we address in our research. Specifically, we combine various active and passive micro-optics components within 3D micro-printed glass assembly and packaging platforms to develop ultra-miniaturized multimodal microscopes designed to provide complementary tissue information. We also develop the hardware and software tools necessary for the acquisition and processing of imaging provided by the endomiscroscopes.

Adaptive optics microscopy

We recently conceptualized and realized a highly-miniaturized, two-dimensionally actuated optofluidic transmissive wavefront modulator, which we refer to as the Deformable Phase Plate (DPP). In contrast to liquid-crystals or deformable-mirrors, this modulator has a large correction range; is free from diffraction, polarization or hysteresis effects; and is both scalable and stackable. It provides a means for inline wavefront correction using a technology which is compact enough for integration into a microscope objective, and yet, due to the two-dimensional arrangement of actuators, scalable to allow correction of higher order aberrations. When coupled with the sensorless wavefront correction algorithm, the DPP can indeed correct for sample-induced, environmental and illumination-related wavefront errors in microscopy. To realize these exceptionally compact Adaptive Optics microscope systems, alongside the optical engineering tasks, we have also developed open-loop control systems for multi-actuator deformable membranes and implemented sensorless wavefront estimation techniques.