Wisconsin Alumni Research Foundation

Analytical Instrumentation, Methods & Materials
Analytical Instrumentation Methods Materials
Piezoelectric Charged Droplet Source for Mass Spectrometry
WARF: P01294US

Inventors: Lloyd Smith, William Berggren, Michael Westphall, Mark Scalf

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a new nanotechnology source that generates single packets of ions for mass spectrometric analysis.
Electrospray ionization (ESI) mass spectrometry holds significant potential for selectively, quickly and sensitively analyzing complex mixtures of large molecular weight biomolecules, such as oligonucleotides and proteins.  However, because ESI produces a continuous stream of ions, rather than discrete packets, or droplets, of ions, it is inherently incompatible with time-of-flight (TOF) mass spectrometry, the most widely used method for detecting large biomolecules.
The Invention
UW-Madison researchers have developed a new nanotechnology source that generates single packets of ions for mass spectrometric analysis. A sample solution held at a selected electric potential is ejected from a narrow exit aperture by constriction of a cylindrical piezoelectric element.

Unlike conventional nanoelectrospray sources that are continuous, this source dispenses discrete volumes (droplets) of electrically charged solutions as small as 10 picoliters. It also allows adjustable control of droplet exit time, ion formation time, droplet number, repetition rate and electric charge state of the droplet. When coupled to an orthogonal time-of-flight mass spectrometer, the source provides detection sensitivity in the attomole range.
  • Mass spectrometryy for genomics and proteomics
Key Benefits
  • Provides a greatly improved source for controlling the location and timing of droplets (and subsequently produced ions), for mass spectrometry
  • Capable of generating charged droplets and gas phase ions of high molecular weight biomolecules, such as proteins and DNA, paving the way toward use of mass spectrometry in DNA sequencing and proteomics
  • Requires extremely small volumes of sample -- inventors have obtained mass spectra from single droplets of 0.1 nanoliter
  • Generates charged droplets directly, in both positive and negative modes, eliminating the need for an external charging device
  • Employs an exit aperture substantially larger than the 1 to 10 micron tips typically found in nanoelectrospray sources, greatly reducing problems such as tip clogging, and difficulties in sample loading and electrospray initiation
  • Source design is compatible with virtually any electrospray ionization (ESI) mass analyzer
  • Provides good uniformity from droplet to droplet
Additional Information
For More Information About the Inventors
For current licensing status, please contact Jennifer Gottwald at [javascript protected email address] or 608-960-9854