SENSORSLow-Power Sensors Could Last 10 Years, Providing Surveillance, Security
Researchers at Sandia have spent the last three years developing an ultra-low-power chemical sensor to detect sarin and other chemical warfare agents or gaseous industrial toxins, aiming to protect the public and warfighters.
Imagine a smoke detector that instead of warning residents of smoke before a fire engulfs their home, is placed in mass-transit locations to alert travelers and first responders to hazardous chemicals in the air.
Researchers at Sandia have spent the last three years developing an ultra-low-power chemical sensor to detect sarin and other chemical warfare agents or gaseous industrial toxins, aiming to protect the public and warfighters.
Sarin is an extremely toxic nerve agent that can cause death within minutes. The production and stockpiling of sarin, along with other nerve agents and mustard gas, are outlawed. However, sarin has been used in terrorist attacks.
“When we’re thinking about ultra-low-power electronics, we want to install a sensor and leave it in the field for a long time,” said Mieko Hirabayashi, a Sandia microelectronics engineer and project lead. “We don’t want to worry about replacing the batteries often.”
Anyone who has changed a smoke detector battery in the middle of the night can appreciate the value of sensors that can operate for a decade without battery replacement.
Spongey Sensor for Sarin
The sensing component consists of a porous, sponge-like material designed to chemically trap sarin and its chemical cousins.
This porous material, called a sol-gel, resembles spray insulation foam. The precursor chemicals are sprayed from a specialized nozzle onto a structure resembling two metal combs with interleaved teeth called an interdigitated electrode, said Philip Miller, a Sandia biomedical engineer on the project. The coated electrode is heated, causing the carrier liquid to evaporate and creating an open “popped bubble” structure.
“The porosity of the material creates more spots for the chemical of interest to land on,” Philip said. “The more molecules the sensor can measure, the faster the alert it can provide. If the sensor is worn on someone’s lapel, it can provide a ‘get out of Dodge’ alert. If the sensor is in the field, it can provide a warning to stay away.”
When a molecule of sarin binds to the sol-gel between the electrode’s teeth, the material’s electric properties change. This property, called capacitance, is detected by the rest of the sensor using minimal power, Philip said.
The team also explored using a different electrical measurement called impedance, which uses more power but is more selective. This would be valuable if the chemical of concern is similar to common airborne chemicals, Mieko said.
The development of the sol-gel material was funded by Sandia’s Laboratory Directed Research and Development program in an earlier project.
