An article including a computer readable medium having instructions stored thereon, which when executed, causes receipt of a control request for a medical-monitoring device located on a client and determining if the control request is serviceable by the medical-monitoring device. Therefore, the problem of being unable to edit complicated multi-media playing schedules due to simple operation interface of digital photo frames can be solved. In another aspect, microfluidic substrates have channels which varying in cross-sectional dimension so that capillary action spreads a fluid only within a limited portion of the channel network. The graduated markings are disposed along a length of the catheter.