By Alex Chen
Featuring Dr. Lan Yang
Our technology is slowly transitioning into smaller and smaller realms. As researchers continue to probe life’s mysteries at the microscopic level, great demand has arisen for related diagnostic and therapeutic technologies. In recent years, the use of nanoparticles has entered the scope of modern medicine, specifically in the fields of medical imaging and drug delivery. The presence of nanoparticles in the air has also increased as a result of modern industrial processes. All this has resulted in an invisible world of nanoparticles all around us and a burgeoning need for effective ways to study the benefits and risks they pose to human health. This has also led to a rising particle detection device market. Study necessarily begins with detection, and researchers at Washington University’s Micro/Nano Photonics Lab, led by Dr. Lan Yang, have developed a revolutionary nanoparticle detector specifically for that purpose.
The detector is based on a phenomenon called the whispering gallery wave. Have you ever visited a domed structure in which you could hear clearly the sounds of people talking on the opposite side of the structure? This phenomenon is accounted for by the whispering gallery wave, a physical phenomenon that was first described by Lord Rayleigh in 1878 after a visit to St. Paul’s Cathedral of London. The nanoparticle detector developed by Dr. Yang and colleagues is analogous to this, but with the gallery shrunk in size to only a few micrometers wide. Additionally, instead of using sound as the medium, Dr. Yang’s particle detector uses light. As a result, it is able to reveal and characterize these elusive nanoparticles by detecting the way they disrupt light patterns in a miniaturized version of a whispering gallery.
How does Dr. Yang’s detector function? The nanoparticle detector’s ‘whispering gallery’ is a donut-like structure about twenty micrometers in diameter instead of a rotunda dozens of meters across. A thin optical fiber called a coupler is used to guide the light into the donuts and index of refraction, through interference of the light. Any nanoparticles detected in the microresonator will scatter light, leading to changes in the peaks. These changes reveal a great deal about the physical properties of the nanoparticle, including its size, shape, and polarizability, which helps researchers characterize and identify the particle.
Why is Dr. Yang’s detector revolutionary compared to existing technology? Traditional detectors require that detection targets be bound with a detectable molecule called a tag. Therefore, to study nanoparticles using this method, one must already be aware of their existence in the sample medium. This significantly limits the potential of discovering new nanoparticles. Even though existing detectors that use surface plasmon resonance (SPR) technology eliminate the need for labels, they are large and unwieldy, sometimes weighing over 100 lbs, preventing on-site detection and stifling portability. SPR sensors also typically cost between $100,000 and $200,000. Dr. Yang’s WGM microresonator-based sensor technology overcomes all of these problems. The sensors developed by Dr. Yang’s lab do not require chemical labeling and can be installed on a chip, offering a vast size advantage compared to present devices. Although full details on the cost of Yang’s device are not available, the production cost of a resonator is less than one dollar. Furthermore, the device would be about the size of a cell phone. This allows detectors to be brought on-site for detection, and allows for scalability in production.
Existing microresonator-based detectors rely on observing differences between peaks in amplitude generated without nanoparticles and peaks that have been altered by the light-scattering effects of the nanoparticle. The presence of nanoparticles causes the peak to shift in frequency or broaden, indicating their presence. However, external factors such as temperature and humidity can also affect peak width or position. This introduces noise into the measurements, as one cannot know precisely to what extent a shift was caused by these external factors. Dr. Yang’s detector has successfully eliminated this key problem. Instead of relying on peak shifts to determine particle properties, the lab instead identified a new a phenomenon in which a particle’s presence causes the original peak to split into two different peaks. While utilizing this requires higher quality micro-resonators, it greatly increases the instrument’s resistance to external noise. The lab found that even though the position of the peaks still shifted with temperature and humidity, their distance relative to each other remained the same. This constancy and predictability makes the resulting measurement more precise. The two modes interfere with each other, generating a beat with a frequency characteristic of the modes’ own frequencies and amplitudes. As more particles enter the detector, the peaks and the beat frequency changes accordingly, revealing much about the properties of the particles detected.
Nanoparticles are increasingly entering into everyday technological applications, ranging from cosmetics to medicine. According to BCC Research, the nanoparticle instrumentation industry was $5.6 billion in 2013 and expected to increase to $7.8 billion by 2019. More specifically nanoparticle sensor industry itself is expected to be worth $227.8 million by 2018, with a compounded annual growth rate of 92% between 2014-2020. Some of the top companies involved in nanoparticle sensor technology include Bosch, Toshiba, Nippon Denso, and Omron.
With their nanoparticle detector, the Yang lab has been able to successfully detect metallic and organic nanoparticles such as gold and polystyrene, as well as individual influenza virions, ranging from 10 to 30 nanometers wide. Yang’s group hopes to push the resolution of their device into the single digit nanometer scale in the future. This innovative device is a promising development in nanoparticle detection and will likely lead to discoveries in nanoparticle properties thanks to its accessibility and accuracy.
E-mail : yang@seas.wustl.edu
Website : http://www.ese.wustl.edu/~yang/
Phone : (314)-935-9543
Lab Address:
Washington University in St. Louis
2104 Green Hall
1 Brookings Dr
St. Louis, MO 63130
Edited by Jeff Bai, Brett Gao
Featuring Dr. Lan Yang
Our technology is slowly transitioning into smaller and smaller realms. As researchers continue to probe life’s mysteries at the microscopic level, great demand has arisen for related diagnostic and therapeutic technologies. In recent years, the use of nanoparticles has entered the scope of modern medicine, specifically in the fields of medical imaging and drug delivery. The presence of nanoparticles in the air has also increased as a result of modern industrial processes. All this has resulted in an invisible world of nanoparticles all around us and a burgeoning need for effective ways to study the benefits and risks they pose to human health. This has also led to a rising particle detection device market. Study necessarily begins with detection, and researchers at Washington University’s Micro/Nano Photonics Lab, led by Dr. Lan Yang, have developed a revolutionary nanoparticle detector specifically for that purpose.
The detector is based on a phenomenon called the whispering gallery wave. Have you ever visited a domed structure in which you could hear clearly the sounds of people talking on the opposite side of the structure? This phenomenon is accounted for by the whispering gallery wave, a physical phenomenon that was first described by Lord Rayleigh in 1878 after a visit to St. Paul’s Cathedral of London. The nanoparticle detector developed by Dr. Yang and colleagues is analogous to this, but with the gallery shrunk in size to only a few micrometers wide. Additionally, instead of using sound as the medium, Dr. Yang’s particle detector uses light. As a result, it is able to reveal and characterize these elusive nanoparticles by detecting the way they disrupt light patterns in a miniaturized version of a whispering gallery.
How does Dr. Yang’s detector function? The nanoparticle detector’s ‘whispering gallery’ is a donut-like structure about twenty micrometers in diameter instead of a rotunda dozens of meters across. A thin optical fiber called a coupler is used to guide the light into the donuts and index of refraction, through interference of the light. Any nanoparticles detected in the microresonator will scatter light, leading to changes in the peaks. These changes reveal a great deal about the physical properties of the nanoparticle, including its size, shape, and polarizability, which helps researchers characterize and identify the particle.
Why is Dr. Yang’s detector revolutionary compared to existing technology? Traditional detectors require that detection targets be bound with a detectable molecule called a tag. Therefore, to study nanoparticles using this method, one must already be aware of their existence in the sample medium. This significantly limits the potential of discovering new nanoparticles. Even though existing detectors that use surface plasmon resonance (SPR) technology eliminate the need for labels, they are large and unwieldy, sometimes weighing over 100 lbs, preventing on-site detection and stifling portability. SPR sensors also typically cost between $100,000 and $200,000. Dr. Yang’s WGM microresonator-based sensor technology overcomes all of these problems. The sensors developed by Dr. Yang’s lab do not require chemical labeling and can be installed on a chip, offering a vast size advantage compared to present devices. Although full details on the cost of Yang’s device are not available, the production cost of a resonator is less than one dollar. Furthermore, the device would be about the size of a cell phone. This allows detectors to be brought on-site for detection, and allows for scalability in production.
Existing microresonator-based detectors rely on observing differences between peaks in amplitude generated without nanoparticles and peaks that have been altered by the light-scattering effects of the nanoparticle. The presence of nanoparticles causes the peak to shift in frequency or broaden, indicating their presence. However, external factors such as temperature and humidity can also affect peak width or position. This introduces noise into the measurements, as one cannot know precisely to what extent a shift was caused by these external factors. Dr. Yang’s detector has successfully eliminated this key problem. Instead of relying on peak shifts to determine particle properties, the lab instead identified a new a phenomenon in which a particle’s presence causes the original peak to split into two different peaks. While utilizing this requires higher quality micro-resonators, it greatly increases the instrument’s resistance to external noise. The lab found that even though the position of the peaks still shifted with temperature and humidity, their distance relative to each other remained the same. This constancy and predictability makes the resulting measurement more precise. The two modes interfere with each other, generating a beat with a frequency characteristic of the modes’ own frequencies and amplitudes. As more particles enter the detector, the peaks and the beat frequency changes accordingly, revealing much about the properties of the particles detected.
Nanoparticles are increasingly entering into everyday technological applications, ranging from cosmetics to medicine. According to BCC Research, the nanoparticle instrumentation industry was $5.6 billion in 2013 and expected to increase to $7.8 billion by 2019. More specifically nanoparticle sensor industry itself is expected to be worth $227.8 million by 2018, with a compounded annual growth rate of 92% between 2014-2020. Some of the top companies involved in nanoparticle sensor technology include Bosch, Toshiba, Nippon Denso, and Omron.
With their nanoparticle detector, the Yang lab has been able to successfully detect metallic and organic nanoparticles such as gold and polystyrene, as well as individual influenza virions, ranging from 10 to 30 nanometers wide. Yang’s group hopes to push the resolution of their device into the single digit nanometer scale in the future. This innovative device is a promising development in nanoparticle detection and will likely lead to discoveries in nanoparticle properties thanks to its accessibility and accuracy.
E-mail : yang@seas.wustl.edu
Website : http://www.ese.wustl.edu/~yang/
Phone : (314)-935-9543
Lab Address:
Washington University in St. Louis
2104 Green Hall
1 Brookings Dr
St. Louis, MO 63130
Edited by Jeff Bai, Brett Gao