GCA: What are applications of glass capillary array?

Glass capillary arrays (GCAs) have a wide range of applications, leveraging their structure composed of dense arrays of parallel, micron-sized hollow channels. The sources describe their use in various scientific and technological fields:

In Analytical Separations:

  • GCAs are fundamental components in two-dimensional capillary electrophoresis (CE×CAE) apparatus for rapid, high peak capacity separations of complex biological samples. This includes coupling a CE 1D separation to an array of independent CE 2D separations. The apparatus involves components like a capillary array holder 'chip', multidimensional separations interface manifold, and a multi-capillary sheath flow cuvette detector.
  • The capillary array can be integrated into a 2D instrument to further separate the effluent of a 1D separation. Examples given include the separation of fluorescein and a serum digest.
  • There is potential for interfacing the capillary array to other liquid-phase separation instruments, such as High-Performance Liquid Chromatography (HPLC).
  • GCAs can also be used in combination with other capillary-based separation modes like micellar electrokinetic chromatography, capillary electrochromatography, capillary isoelectric focusing, and capillary gel electrophoresis.
  • Alternate detection methods, such as absorbance and electrochemical detection, can be used with capillary arrays in analytical techniques.

In Detectors and Sensors:

  • GCAs are used as the glass substrate for fabricating Microchannel Plates (MCPs). MCPs function as fast, lightweight electron multipliers. Applications for MCPs (and thus GCAs used in their fabrication) include:
    • Space flight instrumentation, requiring electron multiplication, fast timing pulses, spatial resolution, and low mass.
    • Image intensification and night vision devices.
    • Photomultipliers for photon and particle detection, often used with scintillators.
    • UV spectrometers.
    • Time of flight (TOF) devices, including terrestrial and space flight mass spectrometers. Curved GCAs are possible for curved MCPs used in instruments like cylindrical mass spectrometers.
    • Scanning electron microscopes.
    • Residual gas analyzers.
    • Generally used as low-mass, low-volume particle and photon detectors due to their high gain and compact structure.
    • Providing spatial information for imaging or determining particle arrival direction.
    • Research applications like Dark Matter Research.
    • Used in High-Resolution Picosecond Photodetectors (HRPPD).
  • GCAs are used in liquid scintillator capillary arrays for gamma imaging, offering high resolution and efficiency.
  • These liquid scintillator detectors are used for particle detection and tracking, capable of differentiating particle types (protons vs. electrons/positrons).
  • Capillary arrays for liquid scintillator detectors have been manufactured for elementary-particle physics applications. In this role, the capillary structure acts as a light guide/transmitter for scintillation light.
  • GCAs are utilised in microfluidic electrochemical devices, serving as micro-porous, high-surface-area electrode architectures when coated with materials like transparent conductive oxide (TCO). They can be used in various electrochemical and solar photoelectrochemical devices.

In Optical and Flow Control Applications:

  • GCAs are used for X-ray concentrators and lenses.
  • They can be used for gas flow collimation and controlled air flow.
  • GCAs have sieve-like filtration abilities and can be used for in-line filtration.
  • Applications include acting as a calibrated leak or a differential pressure barrier.
  • GCAs can function as optical beam splitters and laser entrance windows.
  • Micro-capillary plates (similar to GCAs) can function as thin porous absorbers with wideband absorption properties for acoustics, used for viscous dissipation of acoustical energy.

In Bioscience and Microfluidics:

  • GCAs are listed for applications including DNA Sequencing, Polymerase Chain Reaction (PCR), Cell Sorting, Transfection, and Cell Migration.
  • They are used in Microfluidic Analysis.
  • GCAs enable massively parallel analysis and are described as bioscience multiplexed arrays.
  • They are used in clinical diagnostics.
  • Arrays of precisely sized glass capillaries are used in capillary-based non-contact liquid handling systems for transferring nanolitre volumes, such as in high-throughput screening (HTS).

As Scientific Phantoms and Tools:

  • GCAs are used as a novel phantom for validating Magnetic Resonance Imaging (MRI) pore diameter mapping techniques.

Glass capillary arrays facilitate these diverse applications due to their high length-to-diameter ratio, large active area, high open area ratio, precise pore size, chemical and heat resistance, and the ability for custom fabrication in various shapes and materials.