A sensor for detecting contact of a fluid delivery probe with a fluid surface
and
for detecting fluid flow through the probe includes a first electrode disposed
along a fluid flow path of the probe upstream from a distal tip of the probe and
a second electrode longitudinally spaced and electrically isolated from the first
electrode and disposed at the distal tip of the probe. An oscillating signal is
transmitted through the first electrode, and at least a portion of the signal is
received through the second electrode. Through changes in the received signal due
to the distal tip of the probe coming into contact with a fluid surface or due
to fluid flow through the conduit between the first and second electrodes, fluid
surface contact and fluid flow can be detected. A pressure sensor can be employed
to monitor internal fluid pressure within the fluid conduit of the fluid delivery
probe as a secondary, redundant mechanism for detecting fluid flow through the conduit.
