Chip-Size Spectrometers

The Challenge

Enabling compact systems requires integrating spectrometers into small devices. However, current detection methods and spectrometers:
-	are not robust and easy to manufacture (because they are built from individual components);
-	are bulky and not suited for integration into lightweight, handheld systems; and
-	do not efficiently capture moving analytes.

PARC's Solution

PARC scientists have addressed these needs by designing low-cost yet robust chip-size spectrometers.

These subsystems combine linear variable filters, photo-detector arrays, and a unique reference line technique. The resulting technology features:

• unique light input geometry
  • can be used for large light-emitting areas
  • takes advantage of optical source motion
  • detects analytes continuously and in real-time (as opposed to current "snapshot" approaches)
     
• high performance
  • filter is customizable for high spectral resolution or broad spectral range
  • wide range of photo-detectors can be used for high sensitivity or fast read-out speed
     
• compactness, robustness, and ease of fabrication
  • can be integrated into lab-on-a-chip devices
  • does not exceed the size of the photo-detector array chip
  • has no moving parts and enables monolithic integration
  • leverages existing system components and manufacturing techniques.

How It Works
A linear variable filter transforms the incident spectral distribution into a spatial distribution.   A photo-detector array records the spatial distribution created by the filter, which contains detailed information about the incident spectrum.	The filter converts spectral information from incoming light into a spatial distribution recorded by the detector array.
The reference line, which collects photons of all wavelengths in the spectral range, monitors the intensity distribution across the detector and normalizes the intensity distribution created by the filter.
	Fluorescence spectrum of a moving analyte recorded with PARC's chip-size spectrometer. The intensity of a particle at a particular spot determines the fluorescence intensity in a certain wavelength range.

Applications

• bio-agent detection — including class identification of viruses, bacteria, fungi, and toxins in fluidic and aerosol samples without using reagents [see example]
• health care services such as glucose-level monitoring
• environmental monitoring including water purity and gas analysis
• industrial process control