The project team has collaborated with a Portland, Oregon company, Stevens Water Monitoring Systems Inc, to develop the US Patent-Pending SWEETSense™ instrumentation and data management technology for international applications.
The smart-sensor technology is designed to have a low power profile, while maintaining high resolution data logging capabilities. Currently, data loggers have a tradeoff between frequency of sampling and logging, and energy consumption. However, for these applications infrequent sampling and logging (anything less than every second), can result in missing usage events that are of interest.
The SWEETSense™ technology addresses this issue by sampling at a comparatively high rate, between several times a minute and many times a second, while only logging and relaying the data when a predetermined change in the parameter is sampled. This thereby minimizes power consumption and allows high resolution logging of usage events while running off of compact batteries for a targeted minimum of six months.
The SWEETSense™ combines commercially available front-end sensors, selected for specific applications including water treatment, cookstove, sanitation, infrastructure or other applications, with a comparator circuit board that samples these sensors at a reasonably high rate. The comparator boards monitor the sensors for trigger threshold events that start and end periodic local data logging.
The comparators sample the sensors frequently, and the output is fed into a low power microcomputer chip where the relative time that the parameter change occurs is logged. Logging continues until the parameter returns to a predetermined baseline. The stored events are coded to reduce the amount of data, and thereby the amount of energy required for transmission.
One or more times per day, the comparator board relays logged data events either to another parent board or directly to the internet via Wi-Fi. This second parent board can then relay the data to the internet via Wi-Fi or GSM cellular phone technology. Data processing is enabled on an internet based software program, where the primary algorithms are stored. The internet base program also contains manually and automatically updated calibration files that are periodically and automatically relayed back to the local sensor boards. The innovations in this invention include the processes used to enable long duration operation with high resolution data logging while operating on simple, small batteries; the use of customized and remotely updatable threshold trigger events; and the distributed data processing load between the local sensors and the internet.
The SWEETSense™ Passive Latrine Use Monitor
The SWEETSense™ on the LifeStraw® Family
The SWEETSense™ Fire for cookstove usage and emissions monitoring