Bio Photonics Research

Broadband, coherent light sources are highly valued in R&D. But until now, they have been difficult to achieve without bulky, inefficient tabletop devices. A Caltech team led by professor Alireza Marandi developed an efficient solution to integrating a broad spectrum of frequencies on a microchip. Using an optical parametric oscillator (OPO), the team demonstrated multi-octave frequency comb generation on a nanophotonic device with a threshold of only femtojoules (fJ) of pump energy. The nanophotonic device has the potential to provide ultrabroadband (visible to MIR), on-chip light sources for applications in areas ranging from communications and imaging to spectroscopy . To generate a frequency comb on a chip, the researchers engineered an OPO in lithium niobate (LiNbO3) and used dispersion engineering to shape the way that different wavelengths traveled through the device. An OPO is essentially a resonator that traps incoming laser light at one input frequency and uses a nonlin...

A new expansion microscopy (ExM) technique from MIT makes it possible to use a conventional light microscope to generate high-resolution images at the nanoscale , by expanding specimens 20-fold before imaging them. Historically, nanoscale structures in cells and tissues have been imaged with high-powered, expensive, superresolution microscopes. The new ExM protocol, which achieves 20-fold expansion in just one step, provides a simple, inexpensive method that can be used by most biology labs to perform imaging at a resolution of about 20 nm. “What this new technique allows you to do is see things that you couldn’t normally see with standard microscopes,” professor Laura Kiessling said. “It drives down the cost of imaging because you can see nanoscale things without the need for a specialized facility.” The original version of the ExM technique, developed by professor Edward Boyden and his team in 2015, expanded tissue about 4-fold and provided images with a resolution of around 70 nm...

Researchers at The Institute of Photonic Sciences (ICFO) demonstrated that photons, acting as neurotransmitters, can enable communication between neurons. The researchers developed an all-optogenetic, synaptic transmission system that enabled synthetic signaling between unconnected neurons and the generation of synaptic circuits. The team’s findings could lead to therapies that use light instead of chemicals or drugs to restore communication between nerve cells in the treatment of diseases such as Alzheimer’s and Parkinson’s. In addition to treating neurological disorders, the team’s approach could potentially be used to rewire damaged neural circuits and improve learning. The Photons as Synaptic Transmitters (PhAST) system connects two neurons by using light-emitting enzymes and light-sensitive ion channels. The researchers tested the PhAST system on the roundworm model C. elegans and showed that photon-based synaptic transmission can facilitate the modification of animal behavior. ...

Optical tools can be used to activate biological functions, but with current methods the effects are slow to appear, and sustained effects require continuous light activation. As a result, these light-activation tools provide limited control of fast biological processes and can lead to toxicity in cells and organisms. Although light is a well-established tool for control of bond breakage, it is less firmly established for the control of specific bond formation in complex environments. A team at Tampere University worked with researchers at the University of Cambridge and the University of Pittsburgh to develop a way to use visible light to control irreversible protein binding. The new optical technique for fast, irreversible protein conjugation could be especially valuable in processes where a short initial signal leads to long-term changes in cell or tissue function. Examples include the regulation of gene expression during stem cell differentiation and the activation of immune cells...

S cientists from Brookhaven National Laboratory showed that ionic liquids provide an efficient means to convert one color of laser light into another. The discovery could lead to a way to create lasers with desired colors for a range of medical, scientific, and technological applications. The method is based on the interaction between the laser and different types of ionic liquids (also known as liquid salts). The vibrational energy in the chemical bonds in the ionic liquid cause the laser’s energy to shift and change color. “By adding a certain ion that has a particular vibrational frequency, we can design a liquid that shifts the laser light by that vibrational frequency,” chemist James Wishart said. “And if we want a different color, then we can switch out one ion and put in another that has a different vibrational frequency. The component ions can be mixed and matched to shift laser colors by different degrees as needed.” The new approach to changing laser wavelengths has its root...

Using an approach that combines computer vision, color science, and optical spectroscopy , researchers at Purdue University devised an approach that enables conventional photography to be used for optical spectroscopy and hyperspectral imaging . Using the mechanism, the researchers realized spectral resolution comparable to the resolution of scientific spectrometers with photos from a smartphone camera. A range of industries, running the gamut from agriculture, environmental monitoring, and food quality analysis, to industrial quality control, defense and security, and medical diagnostics, could benefit from the technique, according to its developers. The researchers hypothesized that the RGB values of reference colors, as captured by a traditional camera, could be used to design a spectral color chart that could then be used to decode spectral information. The fidelity of spectral recovery would be determined mainly by the spectral incoherence among the reference colors in the chart....

Myopia, or nearsightedness, is one of the most common ocular disorders worldwide and a leading cause of visual impairment in children. Although specialized eyeglass lenses have been clinically tested to treat myopia progression, an in-depth optical characterization of the lenses has not yet been performed. Researchers from the ZEISS Vision Science Lab at the University of Tübingen and the University of Murcia undertook a comprehensive characterization to investigate the properties of spectacle lenses designed to slow the progress of myopia. The results of their study could help increase the efficacy of future lens designs. Myopia is typically caused when a person’s eyes become elongated, which affects how the eyes focus on faraway objects. The condition can progress in children and teens as their bodies grow. To reproduce pupil shape and myopic ocular aberrations, researchers developed an instrument that reproduced the aberrations in myopic eyes and enabled physical simulation of the...

Since many core components of cells — like DNA, RNA, proteins, and lipids — are just a few nanometers in size and substantially smaller than the resolution limit of traditional light microscopy , the exact composition and arrangement of these molecules and structures is thus often unknown. This results in a lack of mechanistic understanding of fundamental aspects of biology. Drawing on recent improvements to superresolution imaging, including single-molecule localization microscopy, or SMLM, researchers from the Max Planck Institute of Biochemistry and Ludwig-Maximilians-Universität Munich have developed a technique that enhances the resolution of fluorescence microscopy down to the angstrom s cale. The researchers’ technique enables the study of whole and intact cells over individual proteins — all the way down to the distance between two adjacent bases in DNA. The researchers, from the group of Ralf Jungmann, called the technique resolution enhancement by sequential imaging, or RES...

Agate Sensors, a spinout of Aalto University developing smart sensors for material analysis, has raised €5.6 million (~$6.6 million) to commercialize a research breakthrough that shrinks spectroscopy from suitcase-sized lab equipment to a single pixel smaller than a grain of sand — integrated into a chip compact enough to sit on the tip of a finger. The startup’s technology allows devices to analyze the spectral signatures of materials in real time, bringing high-precision material sensing out of the lab and into everyday devices, from smartphones and wearables to medical equipment and defense systems. “We’ve taken a spectrometer once confined to specialized labs and made it small and affordable enough to live inside everyday devices,” said Tommi Leino, CEO of Agate Sensors. “One sensor can shift between functions entirely through software — from diagnosing a health condition to detecting, identifying, and classifying objects and materials — changing how we interact with the physical...

Using high-resolution imaging with two-photon phosphorescent lifetime microscopy (2PLM), researchers learned that even brief interruptions in blood flow to capillaries in the brain can cause rapid, localized drops in oxygen that probably extend into nearby brain tissue. These stalls in blood flow, in the smallest vessels in the brain, could play a role in brain diseases like stroke, Alzheimer’s disease, and traumatic brain injury, where such disruptions are common. Using a two-photon phosphorescent probe, a team comprising researchers from Boston University and Massachusetts General Hospital monitored capillary flux and partial pressure of oxygen (pO2) in the mouse cortex. The researchers sought to quantify oxygen dynamics around capillary stalls as they occurred in vivo. 2PLM provided high-resolution measurement of the pO2 in the brain, enabling the researchers to investigate the distribution and consumption of oxygen. It offered the spatial and temporal resolution necessary to capt...

To help broaden the use of single-photon avalanche diode (SPAD) cameras for multispeckle diffuse correlation spectroscopy (DCS), researchers at the University of Edinburgh developed a data compression scheme for a large-pixel-count SPAD camera using a field-programmable gate array (FPGA). The camera system’s large sensor array enabled a substantial signal-to-noise ratio (SNR) gain over a single-pixel system: The researchers demonstrated an SNR gain of 110, with respect to single-pixel multispeckle DCS, using half of the 192 × 128 SPAD array. The pixel active fill factor was 13% — an order-of-magnitude-larger pixel count than in prior works, according to the team. FPGA compression for large-array multispeckle DCS could democratize the use of SPAD cameras in the biomedical research community, the researchers believe, extending the benefits of multispeckle DCS across many areas of biomedical research. DCS quantifies cerebral blood flow — an important indicator of brain health — by meas...

According to the World Health Organization, 17.9 million people die annually due to cardiovascular diseases. Soft wearable devices are well suited for monitoring physiological signals from electrocardiogram, phonocardiogram, and pulse wave. Advantages of these types of devices include real-time operation capability, skin-like mechanical properties, and high signal-to-noise sensing capability. However, monolithic hemodynamic parameters achieved by current wearable devices cannot adequately and precisely reflect the health status of regional vasculature. Spatiotemporal hemodynamic monitoring techniques are needed to satisfy growing demand for clinical treatment and daily health management of the cardiovascular system. Researchers from Nanjing University have developed a hemodynamics monitoring technique that relies on a configurable, skin-like microfiber Bragg grating group to deliver information on the real dynamics of the systemic cardiovascular system, such as heartbeat, angiectasis,...

Researchers at Chalmers University have developed a method to make microcombs 10 times more efficient, opening pathways to discovery in space and health care, and paving the way for high-performance lasers in a range of technologies. The team has established a company to commercialize the new technology. Laser frequency combs can measure frequency with extreme levels of precision, analogous to a ruler made of light. The principle is based on a laser sending photons that circulate within a small cavity — a so-called microresonator — where the light is divided into a wide range of frequencies. These frequencies are precisely positioned in relation to each other, like the markings on a ruler. Therefore, a new kind of light source can be created consisting of hundreds, or even thousands, of frequencies, like lasers beaming in unison. Because virtually all optical measurements are connected to light frequencies, the microcomb has myriad applications, from calibrating instruments that mea...

Researchers at New York University (NYU) have devised a system of asynchronous, optically driven micro-rotors that could be used to study far-from-equilibrium phenomena such as turbulent weather and biosystems. The advancement could potentially be used to replicate natural phenomena in engineered systems. In vortical flows, which are found in both meteorological and biological systems, particles move into orbital motion in the flow generated by their own rotation, resulting in a range of complex interactions. To better understand these dynamics, the researchers sought to replicate vortical flows at their most basic level. They created a system to move micro-particles using micro-rotors and a laser beam. Direct observation of hydrodynamic coupling between artificial micro-rotors has been restricted by the details of the drive that is used, either through synchronization (using external magnetic fields) or confinement (using optical tweezers). The NYU system is enabled by a tweezing-fr...

Currently, diagnosing diabetes and prediabetes means a visit to a doctor's office or lab work, both of which can be expensive and time-consuming. Research from Huanyu "Larry" Cheng at Penn State has yielded a sensor that can help diagnose diabetes and prediabetes on-site in a few minutes with just a breath sample. Previous diagnostic methods have used glucose found in blood or sweat, but the current sensor however, this non-invasive test uses a sensor to detect acetone levels in breath. While acetone in breath is a normal byproduct from the burning of fat, an acetone level of 1.8 parts per million is a sign of diabetes. “While we have sensors that can detect glucose in sweat, these require that we induce sweat through exercise, chemicals or a sauna, which are not always practical or convenient,” Cheng said. “This sensor only requires that you exhale into a bag, dip the sensor in, and wait a few minutes for results.” While there have been other breath detection methods ...

Tens of millions of people around the world suffer from corneal diseases, with only a small fraction eligible for corneal transplantation. In a recent study, researchers at the University of Ottawa showed that biomimetic materials activated with low-energy blue light can reshape and thicken damaged corneal tissue to promote healing and recovery. The research results could provide a safe way to treat corneal thinning, as well as a practical alternative to corneal transplantation. Further, the dosage of pulsed blue light needed to activate the biomaterial is minimal, which mitigates the possibility of cytotoxic effects from the light. The biomaterial is injected within the corneal tissue after a tiny pocket is surgically created. The injectable biomaterial, which is in the form of a viscous liquid, is made from short peptides and glycosaminoglycans that assemble into a hydrogel when irradiated with low-energy blue light. The hydrogel hardens and forms a tissue-like 3D structure with pr...

An on-demand optical system for exporting target droplets from a static droplet array (SDA) provides a simple way to export specific cells or analytes for analysis without compromising efficiency or accuracy. Researchers at the Qingdao Institute of Bioenergy and Bioprocess Technology of the Chinese Academy of Sciences developed the system, called optical on-demand droplet release (OODR). The developers and their collaborators believe that OODR could promote SDAs as a valuable tool for use with high-capacity screening assays with applications in diverse fields. They said that the technique in its current stage of development has the potential to be used in single-molecule/cell analysis, drug screening, and phenotype-based cell sorting. The OODR system incorporates a 1064-nm laser-responsive indium tin oxide (ITO) layer into a microchamber, array-based, droplet microfluidic chip. When the laser is focused onto the ITO layer of the chip, local heating causes microbubbles to form. The mic...