Advances in technologies such as micro electro mechanical systems (MEMS) have empowered more efficient and smaller digital devices, which can be deployed in WSNs (wireless sensor networks) to gather useful information pertaining to a particular environment. In order to control effectively the physical system in a WSN, actuators may be employed to integrate such environmental information into the automation control system. Indeed, sophisticated entities deployed in wireless sensor and actuator networks (WSANs) act as functional robots. The approach of using the mobile sink, as an example of the actuator to control the movement of a sink, has been adopted by researchers in the past to achieve high efficiency in terms of gathering data from the sensors. This is due to the fact that in general, the sensors alone are unable to control the sink and need to send or relay a smaller amount of packet data. Although a number of methods exist in literature to utilize mobile sinks as actuators, most of these techniques are unable to guarantee data gathering from all of the sensors. As a consequence, more research effort is needed to improve the efficiency as well as fairness of data gathering. In WSANs, sinks and sensor entities should be actively controllable by the administrator. Therefore, we must consider an efficient way to access all nodes in the target networks. In this paper, we propose a novel method, based on the set packing algorithm and traveling salesman problem, to accomplish this goal. The effectiveness of our envisioned method is demonstrated through extensive computer-simulations.