Mercury Switch Protection

To the Editor: In response to my Journal article entitled “How to Build Simple Inexpensive Biofeedback Systems: Suggestion from the Field” (August 1984), I received a letter from Gary DeBaucher, Assistant Professor of Rehabilitation Medicine at Emory University. He suggested that the mercury switch I recommend in my article is breakable and should be encapsulated in some manner. His point is well taken. In the 15 or more years I have used the switch, I have never had one break or a child bite on one, but it is possible. I generally cover the switch with duct tape to prevent damage, but Dr. DeBaucher has a very clever suggestion for those of us with minimal supplies—imbed the switch into the cap of a ball-point pen top and pot it in with epoxy or silicone rubber to cover the switch. (I'd make sure the pen top is not potentially injurious to the child.)… [ ARTICLE][1] [1]: /lookup/volpage/64/1235?iss=8