[China Instrument Network Instrument Development] Recently, researchers at the University of Illinois at Urbana-Champaign developed a new type of plasmon polarimeter sensor, which will be a reliable means of early detection of multiple types of cancer and will also be used for the detection of other diseases. 
Logan Liu and Lynford Goddard, associate professors of electrical and computer engineering at the school, led the research team and their students Abid Ameen and Lisa Hackett were responsible for actually carrying out the project. The team's research paper was published as a cover article in the journal Advanced Optical Materials.
The researchers used a three-dimensional multilayer nanocavity in the nanocup array. Light can be stored in the cavity. The outside of the cavity consists of an insulator surrounding two layers of metal (gold is used here).
It uses plasmon polarimetry, which uses the biomolecules on the surface of the device to detect sensitive interactions between light and matter at the nanoscale. It can produce enhanced field and local fields. Because of the special structure of plasmons, the output coupling efficiency of light is higher when the surrounding refractive index changes.
In this regard, the researcher Ameen explained: "By combining plasmon properties and optical resonator characteristics in a single device, researchers can pass light in the cavity based on the thickness of the multilayer dielectric and the refractive index of the cavity layer, respectively. Concentration within the layer and transport from the top of the device detected low concentrations of biomarkers."
In addition, Hackett added: "This nanocup array has extraordinary optical transmission capabilities. If you use a layer of metal film, try to let light shine through it, and almost no light can pass through. However, you use periodic nanoholes. , or the nanocup structure used in our solution. Then, what you see will be the resonance of a particular wavelength, and the light passing through the device will reach a maximum."
Because the resonance of a single wavelength is constantly changing and the spectral characteristics are related to the reference position, the excitation and detection of light can be reliably performed without special equipment. In this device, the LED light source can replace the laser, phototube or camera imaging can replace the high-end spectrometer.
Hackett said: "Because of this multilayer, high-performance plasmonic structure, we are able to efficiently scatter light to the far field. When the refractive index of the sensing region increases, it couples the stored energy. Typically, when When you have these refractor plasmon polarimeters, you can create angular shifts or wavelength changes when resonance conditions are met. In our case, we have a fixed resonant wavelength because we have integrated nanoresonators."
When the concentration of biomolecules increases (in this case, CEA), the refractive index also increases, so that the transmission intensity of light with a fixed wavelength increases and can be easily detected.
(Original title: New plasmonic sensor: early detection of cancer!)