Spectral Sensing for Biomedical Applications

Spectral sensing refers to measuring the amount of light present within specific spectral bands beyond the typical red, green, and blue channels captured by color cameras. Spectrometry, which has existed for hundreds of years, uses prisms, diffraction gratings, and color filters to separate components of light spectra. Spectrometers find applications in various fields, such as chemistry, physics, astronomy, remote sensing, biology, and more. The information provided by spectrometers is not spatially specific but provides high-fidelity information about the specific wavelengths. While more advanced techniques, such as hyperspectral cameras, can capture both spatial and spectral information.?

Spectral Sensing for Biomedical Applications

Spectral sensing is a technique that can be applied to biomedical applications to measure the light spectrum reflected or emitted from the surfaces of biological samples, the body, or fluorescence emission from labeled cells. It adds to the three primary colors (red, green, and blue) that can be seen by the human eye and, can provide information regarding the type of tissue, its health status, and can assist in detecting diseases. While the human eye can distinguish red, green, and blue colors, it cannot detect subtle differences in the exact peak wavelength of different spectra and their separation. Therefore, spectral sensing supplements what a physician can detect with their eyes and provides enhanced medical care. In medicine, spectral sensing is used to determine the oxygenation level of blood, identify various types of anatomy or organs, locate the borders of cancerous tissue, and detect underlying health conditions such as sepsis or inflammation.

Advancements in Spectral Sensing Technology

In recent years, spectral sensing technology has made significant progress and has found applications in various fields such as biochemical analysis, agriculture, remote sensing, enhanced smartphone camera performance, and wearables. The advancements in these applications have led to the development of mature technology that enables high-fidelity spectral sensing to be integrated into devices like handheld medical devices and mobile phones.

There are several compact, multi-spectral sensors available in the market. For instance, Hamamatsu offers a mini-spectrometer C12880MA that measures 200 channels across 430nm to 850nm and comes in a compact form factor of 20mm x 12.5mm x 10mm. This device is suitable for handheld biomedical sensors for external sensing of the body, biochemical analysis, or open surgery.

AMS-OSRAM has released a product line of very compact, chip-scale spectral sensors that allow up to 18 spectral channels in a 4.5mm x 4.7mm x 2.5mm package.

Small surface-mount chips like this can be integrated into even more compact devices such as dental scanners, surgical cameras, or hand-held diagnostic devices. AMS offers evaluation kits, or this sensor can be evaluated on Arduino-compatible kits such as the one below from Sparkfun.

Viavi specializes in hyperspectral filter arrays (HFAs), which are spectral bandpass filters that can be applied to a photosensor to enable 16 to 300 independent spectral channels.

Spatially sensitive spectral sensing has been employed in surgical imaging in the form of hyperspectral cameras, such as the example by Imec. The snapshot-based camera has been shown to help in the detection of cancer and gliomas, as well as monitor blood flow and oxygenation levels.

Conclusion

Spectral sensing has proven to be a valuable technique that can be applied to various fields, including biomedical applications, agriculture, remote sensing, and more. Recent advancements in spectral sensing technology have led to a mature technology that enables high-fidelity spectral sensing to be integrated into devices like handheld medical devices and mobile phones.? Many future opportunities exist to integrate spectral sensing into various biomedical devices to improve medical care and provide better patient outcomes.