This New Sensing Technology Is The Future Of IoT

March 17, 2017
By Bethany Dunich

Today’s presence-sensing technologies enable everything from movable holiday displays to robust security systems. More specifically, Infrared (IR) Array Sensors allow systems to detect an individual’s presence and their direction of movement, including motionless. This technology can be useful in applications in areas like medical imaging, retail, building automation and security.

Smart Sensors initially started to appear through the encouragement of the U.S. Strategic Defense Initiative (SDI). By the late ‘90s, costs of these devices started to drop and technological advancements persisted, these Sensors began to be used more for both military and civilian purposes, such as automotive collision avoidance systems.

Uncooled IR Sensor technology has been improved with the development of more complex microelectronic systems (MEMS)-based pixel structure. By printing thin-film IR absorbers surrounded by free-standing thermal isolation structures, this MEMS-based technology is created. With this, it is possible to measure radiated power to remotely determine an object’s temperature. Semiconductor technology allows for the development of thermopile Sensors made up of hundreds of thermocouples over several square millimeters. These thermopile array Sensors provider faster response time, are reasonably priced, and are accurate and small. They are ideal for medical instruments, security systems, people counting, building automation and more.

Panasonic Grid-EYE

Panasonic offers an 8X8 thermopile array called the Grid-EYE®. This 64-pixel IR Sensor fits within a reflow-compatible surface mount (SMD) package consisting of a MEMS Sensor chip, an RF-shielded metal cover, a digital ASIC with an I2C interface, and a silicon lens through which the infrared energy passes.

In operation, Grid-EYE first absorbs emitted thermal energy across a 60-degree field of view. Each one of the array’s 64 sensing elements converts the thermal energy it absorbs into a proportional output signal. All 64 temperature signals are then amplified, converted from analog to digital and referenced against an ambient temperature value supplied by the Thermistor, and are then transmitted out of the Sensor into a microprocessor. Once the Sensor outputs the information, the microprocessor maps the temperatures from the individual thermopile elements into a complete thermal representation of the entire field of view. From this thermal grid, it is possible to detect moving people as well as the direction they are moving and the presence of motionless people. The Grid-EYE’s widest thermal detection range is -20°C up to +100°C and it has a maximum recommended detection distance of 7 meters and frame rates up to 10 fps.

When using IR Sensors in applications like security, detection range is an important consideration. To assist designers prototype proximity- and directional-sensing applications, the system board MAXREFDES131# 1-Wire Grid-EYE Sensor by Maxim enabled by the DS28E17 1-Wire-to-I2C master bridge is now available. The DS28E17 interfaces directly to I2C slaves at standard (100kHz max) or fast (400kHz max) speeds, converting the 1-wire communications protocol to an I2C master I/O. The DS28E17 bridge extends I2C communications distance to, typically, 100m at standard speed for a properly configured network. By comparison, the length of an I2C bus in very limited in standard operation, as its maximum distance does not come near the distance that the 1-wire protocol can achieve.

Other applications, like building automation, can benefit from IR Sensor technology. For example, this enables the ability to detect someone’s presence when they enter a room to trigger the lights to switch on, can identify when the room is empty to shut off electronics and also work with the HVAC system to adjust to a preferred temperature depending on the room’s occupancy.

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