An implantable medical device incorporates. Cyanophthalide is prepared in high yields by a convenient procedure. The bar code scanner is connected to the microprocessor to provide bar code data of the bar code to the microprocessor. The topographic second active region may also have a single thickness. The third time interval includes a contention-free period, a contention period, or a combination thereof. Moreover, the optimum synchronized timing instant can be used as a reference instant for bit detection to enhance the capability of resisting noise and waveform distortion.