In exemplary embodiments, {HEAD ~ the capillary channel} may be formed in {TAIL ~ the substrate} or may be a capillary tube embedded in the substrate 
In exemplary embodiments , { HEAD ~ the capillary channel } may be formed in { TAIL ~ the substrate } or may be a capillary tube embedded in the substrate
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH