The apparatus uses a biased electrode for attracting toner particles thereto, and {HEAD ~ a microprocessor based logic and control unit} for sampling {TAIL ~ the mass} of toner particles deposited on the electrode after the deposited toner particles have neutralized the electric field produced by the electrode bias 
for sampling
The apparatus uses a biased electrode for attracting toner particles thereto , and { HEAD ~ a microprocessor based logic and control unit } for sampling { TAIL ~ the mass } of toner particles deposited on the electrode after the deposited toner particles have neutralized the electric field produced by the electrode bias
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