Patent ID: 8116981

Claim:
A method of identifying a cell in a non-gaseous sample, comprising: contacting the non-gaseous sample on a sample plate with at least one enzyme specific for a cell surface marker, such that the enzyme cleaves the cell surface marker from the cell surface; focusing electrons emitted from an electron source in a direction towards a reversal region that comprises the sample plate and an electrostatic mirror to slow down the electrons to zero- or near zero energies; controlling an electric field distribution to match the reversal region to the shape of a surface of the non-gaseous sample on the sample plate, based on a three-dimensional fields-and-trajectories calculation, to cause contacting of the non-gaseous sample on the sample plate with the electrons of zero- or near-zero energies to generate, at the sample plate, ions that include at least negative ions at the cell surface marker; separating negative ions from the generated ions and detecting a pattern of said negative ions; comparing the pattern of detected negative ions to a library comprising fingerprints of ions associated with types of cells; using a match with a member in the library to identify the cell in the non-gaseous sample.