July 28, 2007

Eutectic Mixture : Electronics and Medicine

soldering electronic circuitsAnyone who has done some soldering in electronics, will know how fast the soldering wire melts. The soldering wire comprises of tin 63% (stannum) and lead 37% (plumbum). This alloy melts at a specific temperature of 183 degree centigrade. Also this is the proportion of the two metals, at which the lowest melting point is achieved. The resulting alloy is termed an eutectic mixture, as this has the lowest melting point (not just a range of temperature).

In medicine too, we use eutectic mixtures. For example, when lignocaine (also known as lidocaine) and prilocaine (both are local anesthetics, i.e they anesthetize without producing unconsciousness) are mixed together, they form a liquid like stuff, although individually, both are crystalline in nature. This mixture of local anesthetics is called EMLA (Eutectic Mixture of Local Anesthetics). EMLA has the ability of producing surface anesthesia; which means the application of this mixture on intact skin has the ability to anesthetize that part. Individually, prilocaine or lignocaine does not have the property.

EMLA is used in small surgical procedures. It is used in circumcision, vasectomy (male sterilization), lumber puncture (puncturing the back, to analyze the cerebrospinal fluid) and many other applications including ear surgery and cathterization.
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