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Spectrometer Sensor Chips Offer Potential for Light Sensing With RFID

Ams has released a light and near-IR sensor-on-chip that enables companies to build light-sensing products that can be used as mobile devices, or be built into a permanent sensing network; the two SoCs are expected, in some cases, to be used with RFID to link the identity of a product or location with a sensor reading.
By Claire Swedberg
Jan 18, 2017

Sensor solutions and analog IC company ams has released what it calls the first digital multispectral sensor-on-chip (SoC) products, that also have potential use cases with radio frequency identification and Near Field Communication (NFC) technologies—from tracking the health and growth of plants to managing soil data or identifying counterfeit products. The two new multispectral sensor chips, models AS7262 and AS7263, enable businesses to build mobile or fixed devices that can measure conditions based on visible light or near-infrared (NIR) measurements. The firm released the products this week and now expects companies to build solutions that will, in some cases, feature RFID or NFC technology, as well as Bluetooth, Bluetooth Low Energy (BLE) and Wi-Fi.

The AS7262 is an integrated, six-channel visible spectrometer designed to measure light response, covering 400-nm to 700-nm wavelengths. It includes built-in support for control of an LED–based, or other, light source that shines on a specific target, and the sensor then measures the response. The device can also detect light wavelength directly, as well as detect fluorescence from the test material or space. The AS7263 is also a six-channel spectrometer, but identifies NIR light wavelengths as responses to an LED light beam. NIR detection is typically used for product authentication and document validation, the company explains, as well as to analyze chemicals or track the safety of food or beverages. Visible light measurements, on the other hand, would be more commonly used to monitor changes in a surface's color, absorbance or reflectance, to test water or detect changes in an environment based on visible lighting.

Ams' new system-on-chip is smaller than a U.S. penny.
Tom Griffiths, ams' senior marketing manager for sensor-driven lighting, says companies are already testing the multispectral chips, and that they "will definitely be used in wireless sensing applications." That includes Wi-Fi, cellular or other wireless connections to send sensor data directly to a server, he adds, and companies could also use active RFID technology in the same way. In addition, RFID could be employed not just to carry a transmission from the device to a gateway or server, but also to enable a spectrometer to uniquely identify which item is being sampled, or at what location the sampling data is being collected.

The AS7262 and AS7263 each consume up to 5mA. They lack an internal standby power source, but can be turned off, then turned back on when needed for a sample, thereby limiting power consumption. The AS7262 is intended for visible light response and can be used to detect color changes in something like water. For instance, Griffiths says, testing the PH level of water in a swimming pool currently requires that individuals visually inspect samples of water and determine how they appear after chemical additives are introduced. It is not a very precise system, he says, since they do not have the instruments at the pool to specifically test the PH level, but also cannot afford the time that would otherwise be required to send the sample to a lab where such instrumentation exists. With ams' new spectrometer, users can test pool water or other substances much more precisely in the field. If they have a Wi-Fi or other wireless connection, they can then share that data in real time.

"In this way," Griffiths says, "we bring sensing into the field by making the instrument portable." However, he notes, companies are already beginning to consider applications that would benefit from RFID technology being added to the use case. For instance, food producers are interested in using the NIR version (AS7263) to identify growth activity levels in plants, or the visual light sensor (AS7262) to automatically detect when a plant has begun growing, as well as how large it is.

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