Bio Photonics Research

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...