Optica最新文献

Research into diagnostic biosensors is a vibrant field that combines scientific challenge with translational opportunities; innovation in healthcare is of great societal interest and is an essential element of future healthcare provision. Photonic and electrochemical biosensors are the dominant modalities, both scientifically and commercially, yet the two scientific communities largely remain separated and siloed. It seems astute to better understand what the two fields can learn from one another so as to progress the key scientific, translational, and commercial challenges. Here, we provide an analysis of the fundamental operational characteristics of photonic and electrochemical biosensors using a classification based on energy transfer; in photonics, this separates refractive index sensors from fluorescence and vibrational spectroscopy, while in electrochemistry, it distinguishes Faradaic from non-Faradaic processes. This classification allows us to understand some of the key performance characteristics, such as the susceptibility to fouling and dependence on the clinical matrix that is being analyzed. We discuss the use of labels and the ultimate performance limits, and some of the unique advantages of photonics, such as multicolor operation and fingerprinting, and critically evaluate the requirements for translation of these technologies for clinical use. We trust that this critical review will inform future research in biosensors and support both scientific and commercial developments.

Optical coherence elastography measures elasticity-a property correlated with pathologies such as tumors due to fibrosis, atherosclerosis due to heterogeneous plaque composition, and ocular diseases such as keratoconus and glaucoma. Wave-based elastography, including reverberant elastography, leverages the properties of shear waves traveling through tissue primarily to infer shear modulus. These methods have already seen significant development over the past decade. However, existing implementations in OCT require robust synchronization of shear wave excitation with imaging, complicating widespread clinical adoption. We present a method for complete recovery of the harmonic shear wave field in an asynchronous, conventional frame-rate, raster-scanning OCT system by modeling raster-scanning as an amplitude modulation of the displacement field. This technique recovers the entire spatially and temporally coherent complex valued shear wave field from just two B-scans, while reducing the time scale for sensitivity to motion from minutes to tens of milliseconds. To the best of our knowledge, this work represents the first successful demonstration of reverberant elastography on a human subject in vivo with a conventional frame-rate, raster-scanning OCT system, greatly expanding opportunity for widespread translation.

The technologies to examine the neuronal microenvironment label free remain critically underexplored. There is a gap in our knowledge of underlying metabolic, biochemical, and electrophysiological mechanisms behind several neurological processes at a cellular level, which can be traced to the lack of versatile and high-throughput tools to investigate neural networks. In this paper, four label-free contrasts were explored as mechanisms to study neuronal activity, namely, scattering, birefringence, autofluorescence from metabolic cofactors and molecules, and local biochemistry. To overcome challenges of observing neuronal activity spanning three orders of magnitude in space and time, microscopes had to be developed to simultaneously capture these contrasts quickly, with high resolution, and over a large FOV. We developed versatile autofluorescence lifetime, multiharmonic generation, polarization-sensitive interferometry, and Raman imaging in epi-detection (VAMPIRE) microscopy to simultaneously observe multiple facets of neuronal structure and dynamics. The accelerated computational-imaging-driven acquisition speeds, the utilization of a single light source to evoke all contrasts, the simultaneous acquisition that provides an otherwise impossible multimodal dynamic imaging capability, and the real-time processing of the data enable VAMPIRE microscopy as a powerful imaging platform for neurophotonics and beyond.

We present a two-photon fluorescence microscope designed for high-speed imaging of neural activity at cellular resolution. Our microscope uses an adaptive sampling scheme with line illumination. Instead of building images pixel by pixel via scanning a diffraction-limited spot across the sample, our scheme only illuminates the regions of interest (i.e., neuronal cell bodies) and samples a large area of them in a single measurement. Such a scheme significantly increases the imaging speed and reduces the overall laser power on the brain tissue. Using this approach, we performed high-speed imaging of the neuronal activity in mouse cortex in vivo. Our method provides a sampling strategy in laser-scanning two-photon microscopy and will be powerful for high-throughput imaging of neural activity.