Marktech Expands their Multi-chip Product Line with Multi-Wavelength SWIR LEDs and a 2.6µm InGaAs Detector in One Package

Eliminating the monochromator combined with LED emitters’ higher natural monochromatic nature can produce a higher power excitation light source than a dispersion spectrometer with broadband xenon, halogen, and mercury sources. In dispersion spectrometers, conventional light sources are broken into 128 or 256 wavelengths, with each wavelength having only a fraction of the energy of the source. Higher-power LEDs at specific peak wavelengths can improve the signal-to-noise ratio.

When comparing or discerning two analytes, specific wavelengths provide no additional information when the absorption levels of the two species are equivalent. Therefore, eliminating these wavelengths and using a few critical discerning wavelengths can speed up the overall detection process.

In addition, since a handful of the target excitation wavelengths are picked, each wavelength source can be optimized for high power output and increased wavelength monochromaticity. For instance, additional LEDs with the same wavelength can be packaged in the same TO can, PLCC, or SMD package to provide higher power for a particular wavelength. In addition, Marktech can sort or bin LED emitters to produce tuned LEDs with minimal peak wavelength variation of ±1nm. In higher-volume applications, wavelength variation and power output can be adjusted at the wafer level or in the light-emitting diode fabrication process. Likewise, InGaAs and silicon detectors can be customized during semiconductor fabrication to specific sensitivity ranges – when production volumes warrant the development.

Fluorometers (fluorescence spectrometers) and microscopes utilize a specific excitation wavelength capable of exciting a fluorescent dye or fluorophore in a sample, emitting at a peak emission wavelength. Cells, tissues, and other biological samples are often examined with fluorescence. LEDs eliminate several problems in fluorescence studies compared to older light sources, such as overexposure to light, thermal damage and phototoxicity of the biological sample, and photobleaching of fluorescent dyes or proteins. The peak wavelength of the LEDs can be selected to match the excitation wavelengths of the fluorophores closely. Combined with the higher intensity or power output at the peak wavelength, the result is improved signal-to-noise in fluorometry and fluorescence microscopy applications. Our multi-wavelength LED packages enable the selection of a different excitation wavelength for different fluorophores, fluorescent dyes, or color-indicating reagents. For instance, our MTMD2336T38 multi-wavelength light source can selectively emit 275nm, 310nm, 360nm, and 380nm wavelengths, and our MTMD3334T38 multi-wavelength light source can selectively emit 310nm, 360nm, 380nm, and 430nm wavelengths.

NIR and incredibly SWIR wavelength light can penetrate deeper into human tissue than visible light due to the reduced photon scattering at these wavelengths. SWIR’s high penetration depth enables imaging and spectral information collection deep into tissues. Some of these NIR/SWIR infrared imaging systems have mapped blood flow in live animals and imaged tissue 5mm into mouse brains. In addition, infrared spectroscopy can provide information on deep tissue chemical composition, such as oxygenation and deoxygenation. In the article, “Shortwave infrared fluorescence imaging with the clinically approved near-infrared dye indocyanine green,” the researchers stated that “imaging in the shortwave IR (SWIR; 1,000–2,000 nm) promises higher contrast, sensitivity, and penetration depths compared with conventional visible and near-IR (NIR) fluorescence imaging.” The researchers used NIR and SWIR light sources with an InGaAs detector. Marktech has many singular and multi-wavelength LED emitters in the NIR and SWIR wavelength ranges. For example, the Marktech MTMD142345PDT38 multiple SWIR wavelength emitter-detector contains 1040nm, 1200nm, 1300nm, 1460nm, and 1550nm peak wavelength LEDs combined with our InGaAs photodiode for SWIR detection in the 600nm – 1750nm range. These SWIR emitter-detectors can be helpful in tissue oxygenation and utilization studies using NIRS methods.

In summary, spectrometry, fluorescence microscopy, and other optical analytical methods performed with a specific set of multiple LED light sources and the appropriate photodiode detector can have improved signal-to-noise ratio and detection speed.