The　human　machine　interface　(HMI)　is　a　main　communication　method　between　human　and　computer.　Through　current　HMI,　a　machine　receives　and　accurately　responds　to　the　commands　instructed　by　the　users.　In　the　next　generation　of　HMI,　machines　will　be　required　to　deal　with　more　challenging　problems/decisions　(such　as　affective　evaluations,　ethical　quandaries,　and　other　innovations)　in　a　self-governing　manner.　Thus,　future　HMI　should　be　able　to　provide　information　about　users＇　emotion　to　the　machine　for　affective　evaluation.　In　this　paper,　we　focus　on　the　natural　connection　method　that　can　improve　machines　in　making　the　acquaintance　of　the　users.　However,　connecting　sensors　scattered　on　the　human　body　poses　serious　problems　concerning　comfort　and　convenience.　Therefore,　the　authors　introduce　the　Intra　Body　Communication　(IBC)　for　connecting　various　physiological　sensors　on　the　human　body　such　that　the　physiological　information　can　enrich　the　capability　of　the　computer　in　cognition　of　the　user＇s　emotion.　In　addition,　the　authors　also　reported　two　pilot　studies:　using　the　IBC　for　connecting　the　physiological　sensor　on　the　human　body　and　using　the　physiological　parameters　to　estimate　the　degree　of　fatigue　of　the　user.　©　2012　IEEE.