Originally a technical draughtsman, Sen took on a study in comics at the school of contemporary arts in Sion. He is active as an illustrator in the advertising field from 1989. From 1993 to 1995 he worked as an artist for the Courrier Patronal daily. Sen's humorous drawings and strips have been published in several magazines throughout Switzerland, Belgium and Quebec. Besides comics, Sen is a specialist in illustrating greeting cards. In his native Switzerland, he is mainly known for the 'Agulhon Noël' series, that appears in a Swiss daily. Another comic of Sen is 'Pensées Existentielles'.