What's next in sensor technologies

Randy Ray -- Control Engineering, 10/1/2005

Technical change-agents affecting sensors markets today include developments in smart sensors, sensor buses for distributed networks, semiconductor technology, and sensor miniaturization, in general.

Because industrial sectors are constantly looking for cutting-edge high performance at a lower cost, smart sensors using microcontrollers are adding intelligence and functionality to various sensor technologies and providing simpler, more intuitive set-up. Innovation will move industrial sensor markets into adopting new technologies including smart sensor capabilities, wireless communications, microelectromechanical systems (MEMS)-based components, plug-and-play sensors, and increased precision. Many of these advanced technologies are available now.

Hard-wired network communication will continue to be an important factor in the industrial sensor market. A plethora of bus structures have been offered and some have found their niches. Bus networks used most commonly in the North American sensor market are DeviceNet and Ethernet, with a recent trend toward Profibus over Ethernet.

Simple devices like discrete output or analog output industrial proximity/position sensors typically don't justify investment in bus hardware internal to the sensor. This will change as integrated circuit prices and cost per node of controllers come down. Meanwhile, concentrator blocks remain the preferred method of connecting simple sensors to buses.

Though wireless communication is available for industrial use, it hasn't exactly "arrived." Currently, Bluetooth and ZigBee technologies are the primary contenders. ZigBee standard is a good choice for low bandwidth, low-power applications. Bluetooth, like ZigBee, opens up the possibility of cost-effective, efficient, wireless sensors where data bandwidth and range are more important. The potential wireless market has spurred frantic development in low-power electronics and high-density, low-cost, and safe energy storage devices, as the high power consumption of current sensor designs remains a critical impediment to long-term, cost-effective operation.

Sensor enclosure designs will continue to evolve to address specialty applications, environmental concerns, and increased life expectancy.

Commonly used housing materials, e.g. plastic, stainless steel, and plated metal, are expected to evolve with UV-rated plastics for outdoor use, and FDA-approved materials for use in food and beverage applications, as well as higher grade stainless steels from 304 to 316. IEC enclosure ratings are becoming universally recognized and new ones are being added to address the need for improved sealing characteristics.

Although slow to evolve, housing shapes and design will proliferate to meet special needs of OEMs and large-volume end-users. Ability to provide a quick response custom package will be a strong competitive advantage for most sensor manufacturers.

In addition, a revolution in miniaturization is under way. MEMS are widely used in pressure sensors and will most likely be applied to other industrial sensor technologies, such as ultrasonic and capacitive proximity/position, force, chemical, and inertial. Maturation of MEMS fabrication and packaging technology will spawn low cost, miniature smart sensors with additional capability at lower cost.

In all, the industrial sensors market remains strong as competition and technical development push functions higher and prices lower, therefore justifying their use in machinery and processes that previously went unmonitored.