This study reports the results of our recent in vivo study using attenuation-based quantitative OCT for intra-operative mapping of brain cancer in patients. A total of 34 brain cancer patients were recruited, and an optimal optical attenuation threshold of 4.3 mm-1 was established with cancer of lower values. We achieved an excellent specificity of over 98%, with a corresponding sensitivity of over 95% for both high-grade and low-grade cancers. Applying the established optical attenuation threshold to infiltrated tissues, we were able to identify regions of cancers qualitatively matching the neuropathologist’s assessment. The study suggests that optical attenuation-based quantitative OCT represents a promising technology for intraoperative brain cancer detection and
Cellular photomodulation holds promising potential in biomedical research, However, this technique is typically performed manually at low speed. We have successfully developed an integrated femtosecond laser (fsL) cell stimulation system based on a constant radius lab-on-a-disc (LOAD) platform in which a concentric microchannel for rearranging cells to a monolayer under centrifugal force can be engraved in a polymethyl methacrylate layer in situ while the disc is in spinning mode. The system can perform multi-photon cell stimulation, which subsequently leads to molecular signaling modulation of cells in a high-throughput and highly automatic manner.
This project was supported by General Research Fund (GRF) : 14204621, 14207920 and 14207419.
Endoscopic optical coherence tomography (OCT) offers near histologic quality visualization of tissue microanatomy in vivo, circumventing the challenges of traditional biopsy by enabling volumetric sampling without tissue removal. Miniaturized probes have been designed to overcome the limited imaging depth of conventional OCT, thereby facilitating minimally invasive imaging. Visible light OCT (vis-OCT) endoscopy has the potential to achieve ultrahigh resolution of less than 2μm with enhanced image contrast. However, current vis-OCT endoscopes, which rely on achromatic lenses and distal motors, are cumbersome and pose safety concerns in clinical environments, underscoring the need for ultracompact, current-free alternatives. Additionally, conventional fabrication methods for high-performance, ultrathin vis-OCT endoscopes have limitations. In this study, we introduce a submillimeter monolithic vis-OCT endoscope, created by directly coupling microlens to the fiber tip using a liquid shaping technique. Our ultrathin vis-OCT endoscope of 0.4mm in outer diameter enables ultrahigh-resolution (1.4μm × 4.5μm in axial and transversal directions) interstitial imaging in vivo.
To effectively manage inoperable deep-seated brain diseases, a high-resolution diminutive endoscope is required. This endoscope should be capable of precisely localizing and evaluating lesions in vivo. In this study, we introduce an ultrathin robotic OCT neuroendoscope designed for minimally invasive and targeted imaging in the deep brain. The neuroendoscope, measuring only 0.6mm in diameter, is fabricated by coupling a custom micro-lens on the fiber tip. This fabrication technique enables high resolution imaging of 2.4μm × 4.5μm in the axial and transverse directions. To ensure precise trajectory planning and accurate lesion localization within the brain, we have developed a skull-mounted robotic neuroendoscope positioner, allowing for a localization accuracy of approximately 1mm. To demonstrate the capabilities of our technology, we have utilized electromagnetic tracking technology to enable us to control and navigate the neuroendoscope, allowing for the precise localization and imaging of targets within a brain phantom. The new technology holds significant potential to translate OCT neuroendoscopy into clinical practice for deep brain conditions.
The imaging depth of optical coherence tomography (OCT) in highly scattering biological tissues (such as luminal organs) is limited, particularly for OCT operating at shorter wavelength regions (such as around 800 nm). For the first time, the optical clearing effect of the mixture of liquid paraffin and glycerol on luminal organs was explored with ultrahigh-resolution spectral domain OCT at 800 nm. Ex vivo studies were performed on pig esophagus and bronchus, and guinea pig esophagus with different volume ratios of the mixture. We found that the mixture of 40% liquid paraffin had the best optical clearing effect on esophageal tissues with a short effective time of ∼10 min, which means the clearing effect occurs about 10 min after the application of the clearing agent. In contrast, no obvious optical clearing effect was identified on bronchus tissues.
Focused ion beam (FIB) is a highly versatile technique which helps to enable next generation of lab-on-fiber sensor
technologies. In this paper, we demonstrate the application of FIB to precisely mill the fiber taper and end facet of both
conventional single mode fiber (SMF) and photonic crystal fiber (PCF). Using this technique we fabricate a highly
compact fiber-optic Fabry-Pérot (FP) refractive index sensor near the tip of a fiber taper, and a highly sensitive in-line
temperature sensor in a PCF. We also demonstrate the potential of using FIB to selectively fill functional fluid into
desired patterns of air holes in a PCF.
In this paper we present our latest work on Fiber Bragg Gratings (FBGs) in microstructured polymer optical fibers
(mPOFs) and their application as strain sensing transducers in devices, such as accelerometers and microphones. We
demonstrate how the cross-sensitivity of the FBG to temperature is eliminated by using dual-FBG technology and how
mPOFs fabricated from different grades of TOPAS with glass transition temperatures around 135°C potentially allow
high-temperature humidity insensitive operation. The results bring the mPOF FBG closer to being a viable technology
for commercial applications requiring high sensitivity due to the low Young's Modulus of polymer.
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