Microscale mass spectrometric chemical-gas sensor

A mass sensor comprising a magnet assembly and a mass analyzer, said mass analyzer comprising:

• a housing having a cavity therein, said housing comprising a first plate, a second plate, and a center portion positioned between said first and second plates, said center portion comprising an outer wall;
• an ionizer;
• a double focusing mass spectrometer having superimposed orthogonal magnetic and electric fields;
• and
• an ion detector, said ionizer, said double focusing mass spectrometer, and said ion detector located in said housing cavity;
• said double focusing mass spectrometer comprising an electric sector energy analyzer, said electric sector energy analyzer comprising:
• a first element located on an inside surface of said first plate;
• and
• a second element located on an inside surface of said second plate, said first and second elements substantially concentric and congruent and having a circular arc shape, each said first and second element comprising:
• a first boundary electrode;
• a second boundary electrode;
• and
• a continuous resistive material extending between said first and second boundary electrodes.