Final answer:
A continuous sampler collecting airborne particles onto a filter for analysis is called an Impinger. Mass Spectrometry, and specifically MALDI-TOF, is a separate technique used to identify substances by mass-to-charge ratios but is not the portable biological agent detector described in the question.
Step-by-step explanation:
A continuous sampler that collects or traps airborne particles onto a filter for analysis is a device known as an Impinger. This device works by pulling air through a specially designed liquid that captures the particles. After collection, the sample can be analyzed to identify the presence of biological agents. In contrast, a Mass Spectrometer is extensively used to identify chemical and biological substances by their mass-to-charge ratios. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) is a sophisticated technique where organisms are mixed with a matrix reagent on disposable MALDI plates and then ionized by a laser, with the resulting ions being separated in the mass spectrometer based on their velocity determined by their mass-to-charge ratio.