This invention relates to a muffler to be used in the exhaust system of an engine for automobiles, specifically to a muffler including a sound absorbing material interposed between the external tube and the internal tube, and a method of manufacturing the same. Further, the present invention provides an immobilized enzyme for esterification, which sufficiently exhibits its activity and prevents the enzyme from being left or inactivated, thus promoting the esterification reaction. The second pixel electrode is electrically isolated from the first pixel electrode. A corresponding DC circuit breaker and AC current limiter are also presented.