Portable sensors battery life

The picture of the packaged unit reminds us of the ancillary systems necessary to form a useful portable sensor. In this unit they project a 4-hour battery life with a lithium ion battery. They have a pumping system that supplies air at 1.5 L per minute. It also contains an analog-to-digital converter capable of 200,000 samples per second at 14 bits and a personal digital assistant for control and data analysis. 

Development of a Diffusion Head Sensor Cell. The use of air sampling pumps in portable electrochemical gas detection apparatus introduces potential problems into the instrument. First, the sensor cell response is dependent on gas flow rate. The sample flow rate, therefore, must be accurately controlled to obtain reproducible results, or the sample flow rate must be set high enough to insure a flow independent response. Secondly, failure of the pump itself could prevent a sample from reaching the sensor cell. Thirdly, the pumps are usually one of the largest users of current in a portable instrument and thereby limit usable battery life. 

As described in the previous section, the challenges of size reduction, comfort, battery life, and motion artefacts remain unsolved in current portable pregnancy monitors. In general, these issues have been addressed by the wireless sensor network (WSN) community. More specifically, they are researched under the name of wireless body area network (WBAN) (Gonzalez-Valenzuela et al., 2013 Yang, 2006 Latre et al., 2010 Chen et al., 2010). 

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