This paper presents the advantages of smart sensors, among which stands out the SHT71 temperature/humidity sensor. This sensor is suitable for the development of embedded systems for monitoring environmental parameters. The paper is divided into two parts. The first part will cover the details regarding the sensors, including their specification, interface and communication protocol. The second is an application example of the sensor of measure humidity and temperature. The application involves the design and implementation of a wireless sensor network (WSN) to monitoring relative humidity and temperature using a SHT71 sensor, two microcontrollers and two Xbee modules. Processed data can be displayed by LCD, but also can be sent to the host computer or store in an external SD card. The results show that the system has a simple structure.