Two sensors have been developed that can sort out spoiled foods in a processing plant or find contaminants in medicines without resorting to the bulky equipment used in laboratories. The miniature spectral analyzers are the latest effort to pack entire pieces of lab equipment into silicon chips.
The sensors, devised by Austria’s Ams, use what is known as multispectral imaging to view many bands of infrared and visible light simultaneously. That insight provides a clearer view of everything from the ripeness of an almond to the distribution of an invasive plant species. Both sensors work over six different bands, the company said.
Many of the early multispectral imaging systems were used on satellites taking photographs of the earth’s surface to inform fields like geology, forestry, and regional planning. In recent years, satellite systems like Landsat have been used extensively for mapping climate change and tracking the health of farms and animal habitats.
But the latest sensors are different. They are built with a new fabrication technology that enables optical filters to be deposited directly onto silicon chips, Ams said. The technology filters out light interference that could corrupt sensor readings, while being much smaller and cheaper than components used in traditional spectral analyzers.
“The dramatic reduction in the size and cost of spectral analysis enabled by our new spectral sensing solutions brings the lab to the sample,” said Jean Francois Durix, Ams’s marketing director for emerging sensors systems, in a statement. A factory worker could carry around a handheld spectral analyzer to check product quality, instead of having to take the product to the lab.
The sensors could also be plugged into smartphones. At the Consumer Electronics Show in Las Vegas, a start-up called Consumer Physics revealed a smartphone using its infrared sensors to relay a person's body fat, the sugar content of fruit, or identify real pills from counterfeits. Though the sensor’s accuracy has been disputed, it will ship in the Changhong H2 smartphone in China this year.
There are similar efforts to measure the chemical compositions of fluids using sensors that emit infrared light and analyze molecules reflecting the light back. Last year, MIT scientist Anurahda Agarwal and her colleagues created glass lenses that emit infrared light to measure chemicals. She highlighted applications like quality monitoring in a water purification plant and inspecting food for freshness.
While such sensors might be years out, the Ams sensors are in volume production. The AS7262 can simultaneously measure six bands of visible light, while the AS7263 detects six bands in the infrared spectrum. Both devices, which measure 4.5 by 4.4 millimeters, contain an electronic shutter that accurately controls the light source emitting from the sensors.