The photonics community can make important contributions to the fight against the COVID-19 pandemic—from the diagnosis of the disease to the genetic analysis of the SARS-CoV-2 virus, and from the development of vaccines to the decontamination of protective equipment. In our interview, Dr. Thomas Baer, Executive Director of the Stanford Photonics Research Center, and Dr. Christina Baer, Director of the Sanderson Center for Optical Experimentation (SCOPE) at the University of Massachusetts Medical School (UMMS), share insights in the role of Optics and Photonics for the fight against the pandemic.
Dr. Christina Baer: At our institutes, we both conduct interdisciplinary research at the intersection of medicine, optical technologies and engineering to help advance clinically relevant research and develop devices for clinical use.
Dr. Thomas Baer: Now, that the impact of the global pandemic COVID-19 has reached staggering dimensions, with more than four million diagnosed cases and over 280.000 deaths, scientists, engineers and medical doctors have mobilized. We need all our creativity to address the enormous challenges posed by this pandemic. We can rely on known photonic technologies, but we must also break new ground.
Thomas Baer: This begins with early detection and screening of the disease. Due to the wide variability in the disease’s symptoms, fever measurements deliver the most reliable information in the early stage. Because of the pathogenicity of SARS-CoV-2 virus, remote, non-contact options that employ infrared imaging cameras to simultaneously image and measure groups of individuals provide a significant safety advantage. For individual diagnostics, it is appropriate to use non-contact infrared-based thermometers for measuring forehead temperature. This kind of thermometer is based on single detectors or on arrays of micro-bolometers or semiconductor diode detectors, which are sensitive in the far-infrared spectral region from eight to fourteen micrometers. They detect changes in the blackbody radiation intensities. If COVID-19 is likely, the screening continues with photonics-based precision molecular diagnostics to detect the RNA of the virus …
Christina Baer: … the so called real-time reverse transcription polymerase chain reaction, which is better known by its abbreviation RT-PCR. The instruments use highly sensitive spectroscopic methods to detect extremely small quantities of viral genetic material from patient’s nasal or throat swab. The procedure requires significant sample processing. The method works by copying specific nucleic acid sequences within the sample, using probes—nucleic-acid primers—that selectively bind specifically to the RNA sequences present in the SARS-CoV-2 virus. The probes are tagged with molecules of fluorescent dye. After up to 40 cycles of amplification, in which the nucleic-acid sequences bound to the probes get copied with the addition of enzymes and temperature, it is possible to estimate the viral load. After each amplifying cycle, the instrument measures the overall fluorescence, which increases with the amount of virus in the probe. Real-time RT-PCR instruments employ narrowband visible laser diodes or LEDs as excitation sources and semiconductor diodes or photomultipliers with narrow band-pass optical filters for detection. These instruments are fully automated and can typically process 96 or 384 samples in parallel in approximately 2 hours. To accelerate testing, researchers are currently experimenting with dry sampling swabs, the preparation of which is less complex. An alternative photonics-based diagnostic option is high-resolution computed tomography (CT) scans, which enable physicians to identify lung tissue affected by COVID-19.
Thomas Baer: If the disease is diagnosed, it is crucial to monitor the patient’s lung function. For this purpose, oximeters measure the oxygen saturation of the blood—or more precisely the percentage of oxygenated hemoglobin. The miniaturized devices use LEDs emitting at two different wavelengths, typically around 665 and 894 Nanometer. The oxygen-saturation percentage is measured from the ratio of the absorption at these two wavelengths.
Christina Baer: Yes. Modern laboratories are using highly automated instruments, that can analyze hundreds to thousands of samples per day. They make use of the Enzyme-Linked Immunosorbent Assay (ELISA) to measure the presence of antibodies specific to the virus in a patient’s blood-serum sample. This technique relies on a colorimetric change in the sample generated by an enzyme attached to antibodies specific to SARS-CoV-2 virus, which can be detected via multispectral imaging.
Thomas Baer: Optical technology is crucial not only for antibody testing, but also for vaccine development. They are core-components for the most common high-throughput gene-sequencing instruments, whose development received an enormous boost through the Human Genome Project. The devices typically use high-quantum-efficiency, very-high-resolution multispectral cameras to map sequences of hundreds of millions of target DNA molecules simultaneously. They can sequence the complete genome of the SARS-CoV-2 virus in just a few hours. This is crucial for tracking the virus—for genetic sequences can vary with geographic location due to mutations of the virus. And the technology is also enabling the development of vaccines: High-throughput sequencing can help determine the proteins in the virus and potentially identify targets for synthetic vaccines that will stimulate immune response.
Thomas Baer: Clinics all over the world need quick and reliable procedures to safely sterilize personal protective equipment (PPE)—for instance masks or N95 respirators—as well as instruments or surfaces. Light in the UV-C-spectral region (200-280 nanometers) kills many bacteria and viruses with exposure times of one to five minutes at high UV-C light intensities. UV-LEDs and mercury-based germicidal lamps are tested in innovative designs and engineering approaches to make this technology quickly available. If readers from our community are willing to contribute their knowledge, ideas and technology, please visit n95decon.org! Especially in regions lacking PPE and N95 respirators, clinics and physicians urgently need simple but reliable solutions for rapid decontamination and subsequent reuse of the vital equipment.
Christina Baer: Get in touch with those who work at the frontlines. Scientists, physicians, nurses—and ask them what tools they need and where the problems are right now. Team up with scientists and physicians to increase the knowledge about this new virus as quickly as possible. In the fight against this unprecedented pandemic, we need cross-disciplinary approaches and tons of commitment! You should keep in mind: Photonics are crucial for the fight against COVID-19.
Dr. Christina Baer is the Director of the Sanderson Center for Optical Experimentation (SCOPE), which is a catalyst for optical experimentation at the University of Massachusetts Medical School (UMMS). She is also an assistant professor in the Microbiology and Physiological Systems department at UMMS. Her research focusses on the use of innovative optical techniques to answer fundamental questions regarding cellular growth and division or intracellular signaling in the field of specific lung diseases. The technological spectrum ranges from wide-field, confocal and multiphoton imaging to the development of molecular tools and quantitative image analysis.
Dr. Thomas Baer is Director of the Stanford Photonics Research Center, which is developing instrumentation for life science and biomedical research by utilizing custom optical, mechanical, microfluidic and electronic design. This involves imaging and biochemical analysis technology for exploring the molecular basis of human developmental biology and regenerative medicine, optogenetics, and the development of technologies for protein engineering.
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