The lifetime of wireless sensor networks deployments depends strongly on the nodes battery state of health. It is important to detect promptly those motes whose batteries are affected and degraded by ageing, environmental conditions, failures, etc. There are several parameters that can provide significant information of the battery state of health, such as: the number of charge/discharge cycles, the internal resistance, voltage, drained current, temperature, etc. The combination of these parameters can be used to generate analytical models capable of predicting the battery state of health. The generation of these models needs a previous process to collect dense data traces with sampled values of the battery parameters during a large number of discharge cycles under different operating conditions. The collected data allow the development of mathematical models that can predict the battery state of health. These models are required to be simple because they must be executed in motes with low computational capabilities. The article shows the complete process of acquiring the training data, the models generation and its experimental validation using rechargeable batteries connected to Telosb motes. The obtained results provide significant insight of the battery state of health at different temperatures and charge/discharge cycles.

Metal Oxide Semiconductor or MOS-type gas sensors are resistive sensors which can detect different reducible or volatile gases in atmospheres with oxygen. These gas sensors have been used in different areas such as food and drink industries or healthcare, among others. In this type of sensor, the resistance value changes when it detects certain types of gases. Due to the electrical characteristics, the sensors need a conditioning circuit to transform and acquire the data. Four different electronic topologies, two different MOS-type gas sensors, and different concentrations of a gas substance are presented and compared in this paper. The study and experimental analysis of the properties of each of the designed topology allows designers to make a choice of the best circuit for a specific application depending on the situation, considering the required power, noise, linearity, and number of sensors to be used. This study will give more freedom of choice, the more adequate electronic conditioning topology for different applications where MOS-type sensors are used, obtaining the best accuracy.