Lihong Wang, PhD, continues to build on his groundbreaking technology that allows light deep inside living tissue during imaging and therapy.
In the Jan. 5 issue of Nature Communications, Wang, the Gene K. Beare Professor of Biomedical Engineering at Washington University in St. Louis, reveals for the first time a new technique that focuses diffuse light inside a dynamic scattering medium containing living tissue. In addition, they have improved the speed of optical focusing deep inside tissue by two orders of magnitude. This improvement in speed is an important step toward noninvasive optical imaging in deep tissue and photodynamic therapy.
Washington University in St. Louis
Lihong Wang, PhD
In the new research, Wang and his team have built on a technique they developed in 2010 to improve the focusing speed of time-reversed ultrasonically encoded (TRUE) optical focusing for applications in living tissue. To focus light, the engineers use a virtual internal guide star at the targeted location. By detecting the wavefront of light emitted from the guide star, they can determine an optimum phase pattern that allows scattered light moving along different paths to focus at the targeted location.
When light is shined into living biological tissue, breathing and blood flow changes the optical interference, or speckle pattern, which can cause previous methods to focus diffuse light inside scattering media to fail. Scientists have to act quickly to get a clear image.
The new TRUE technology combines two techniques: focused ultrasonic modulation and optical phase conjugation. Researchers use a type of mirror to record then time-reverse the ultrasound-modulated light emitted from the ultrasonic focus to achieve the best focus. Previously, technology limited the speed of TRUE focusing to no more than 1 Hz.
To overcome this obstacle, the team used a fast-responding photorefractive crystal that is sensitive to light at the 790-nanometer wavelength, making it suitable to focus light deep into biological tissue. The new TRUE technology is able to focus light inside a dynamic medium with a speckle correlation time as short as 5.6 milliseconds. The improved speed allowed Wang to achieve the first optical focusing of diffuse light inside a scattering medium containing living biological tissue.
Going forward, the team plans to implement the system in a reflection configuration, where light is shined and detected on the same side of the tissue.
The School of Engineering & Applied Science at Washington University in St. Louis focuses intellectual efforts through a new convergence paradigm and builds on strengths, particularly as applied to medicine and health, energy and environment, entrepreneurship and security. With 91 tenured/tenure-track and 40 additional full-time faculty, 1,300 undergraduate students, more than 900 graduate students and more than 23,000 alumni, we are working to leverage our partnerships with academic and industry partners — across disciplines and across the world — to contribute to solving the greatest global challenges of the 21st century.
Liu Y, Lai P, Ma C, Xu X, Grabar A, Wang LV. Optical focusing deep inside dynamic scattering media with near-infrared time-reversed ultrasonically encoded (TRUE) light. Nature Communications, online Jan. 5, 2015. DOI: 10.1038/ncomms6904.
Funding from the National Institutes of Health (DP1 EB016986 and R01 CA186567) supported this research.
Asst. Vice Chancellor for Campus Communications
Julie Flory | newswise
Novel PET imaging agent could help guide therapy for brain diseases
03.04.2018 | Society of Nuclear Medicine and Molecular Imaging
New Computer Architecture: Time Lapse for Dementia Research
29.03.2018 | Deutsches Zentrum für Neurodegenerative Erkrankungen e.V. (DZNE)
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
24.04.2018 | Information Technology
24.04.2018 | Earth Sciences
24.04.2018 | Life Sciences