{HEAD ~ The preconcentrator} consists of a substrate with passageways, {TAIL ~ a conductive material} coated to the top and the bottom of the substrate and an adsorbent coating covering the entire substrate 
consists of
{ HEAD ~ The preconcentrator } consists of a substrate with passageways , { TAIL ~ a conductive material } coated to the top and the bottom of the substrate and an adsorbent coating covering the entire substrate
HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH