Question

Monopolar needle electrode have a coating of which material over the stainless steel wires which are bare only at the tips?

(a) carbon

(b) calcium

(c) sodium

(d) teflon

The question was posed to me in a national level competition.

My enquiry is from Biosensors topic in portion Physiological Transducers of Biomedical Instrumentation

Answer 1

Right option is (d) teflon

To explain: The monopolar needle electrode consists of a teflon coated stainless steel wire. The wire is bare only at the tip. It is found that after the needle has been used a number of times, the teflon coating will recede, increasing the tip area. The needle should be discarded when this happens.