Smaller, smarter, and low cost -- that defines the present and future of sensing technology. Banner Engineering vice president of sales and marketing Floyd Schneider sees a marked trend towards "smaller sensors with the same or better performance."

Banner's VS2 Series convergent-mode sensor (pictured) measures a scant 25.1 mm high x 12 mm wide x 3.6 mm deep, for example, and replaces remote and fiber optic devices. The company's World-Beam universally mountable photoelectric sensor runs 35 mm high x 15 mm wide x 31 mm deep, and is available in all sensing modes, with opposed mode sensing range of 20 m and retroreflective mode range of 6 m.

Cost containment remains one of the key challenges for sensor manufacturers. Banner helps hold down costs by using "pick-and-place machines that place parts at the rate of 40,000 components per hour," Schneider says.

"As sensors become less and less expensive, we see continued growth in almost all areas," he continues. Prices are "now low enough that many OEMs can justify" substituting sensors for simple switches. Meanwhile the semiconductor/electronics industry "will continue to demand smaller sensors with more intelligence than ever before," Schneider believes.

"We are seeing a rapid increase in the numbers and types of sensors with extended sensing ranges," notes Jim Dunn, sensors product manager at Carlo Gavazzi Inc. "To go along with that, there is a definite trend towards 'miniaturization' of sensors. Additionally, there is a growing development of 'smart' sensors -- sensors with on-board diagnostic capabilities, self-teaching, etc."

Dunn is concerned that the "growing use of e-commerce and direct selling to end customers will have the effect of stifling revenue and/or gross profits," straining R & D budgets as a result and possibly slowing the development of advanced products. The product manager believes that the "greatest potential for growth lies in fiber optic technology. As the semiconductor/electronics manufacturing industry grows, so will demand for sensors that can detect smaller objects."

Sensor manufacturers "continue to push the envelope in terms of decreasing size," according to Dave Quebbemann, industrial automation marketing manager at Omron Electronics Inc. "There's been improvement in sensing distance and auto power control. On top of that, sensors are smarter...some sensors have the ability to become a network device." Omron's E3X-DA-N, for example, includes an auto power control feature, and its APC circuits are "applied in the fiber sensors to avoid deterioration of the incident of the LED and unstable detection."

The key challenge for the sensors sector in the next five to ten years will be to incorporate a variety of fieldbus technologies "while maintaining a small package size at an affordable cost," the Omron marketing manager believes. He thinks the greatest area of growth in coming years will be in low-end vision. "There's always a need in the factory to reduce the level of human involvement while increasing accuracy. Vision technology has achieved a lower price point, which has made it much more affordable."

The digital revolution is leading to smarter sensors, concurs John Register, product marketing manager for Raytek Automation Products Div. (Raytek's MID sensor, pictured, comes with RS232 or RS485 output.) "One example is signal processing, which historically has only been available through the smartest control systems but can now be done right at the sensor." Infrared measurement technology is fundamentally the same as it was five years ago, Register states, but its cost "continues to drop. A sensor that would have cost $1200 in 1990 could be purchased for $600 in 1995, and today a sensor with similar performance is available for $350."

Low-cost A/D used with digital microcontrollers keeps increasing sensing flexibility. "On some microcontrollers, an RS232 output is standard," says Register, and "making this signal available at the output of the sensor provides a valuable feature for very little additional cost."

One of the more significant concerns facing the infrared temperature measurement industry is the "increasing availability of low-performance, low-cost sensors from unqualified suppliers," Register adds. " The global economy is enabling significant growth in the number of manufacturers of IR temperature sensors; inexperienced suppliers are trying to learn the business by attracting IR customers in established markets to be their 'beta-sites'. The absence of international standards for infrared temperature measurement means startup companies, with little or no experience in the technology, can get a low-cost product to market which is so poorly designed that its lack of performance may sully the image of the entire IR temperature measurement industry."

Even so, the portable infrared temperature measurement market "continues to grow at a heady pace [and] as new markets open with steadily decreasing prices, this trend should continue."

Robert Black, director of Turck Inc.'s sensor division, tells IEN that customers are looking for smaller packages, more sensing range and better improvements in noise immunity and sealing against contaminants.

Sensor manufacturers worry about the availability of PCB components. Rising demand "has led to raw material shortages that in turn may lead to increased deliveries of finished product to the end user," Black warns. At the same time, manufacturers are expanding sensing ranges within current product families and developing new package sizes "while using existing circuit boards, thus cutting development time." He expects sharp growth in demand for custom shapes for specific applications.

With background suppression (BGS) technology today's discrete sensors can ignore reflective backgrounds, tolerate color changes, and detect targets with very low reflectivity, while allowing for true adjustable sensing distances, says Tom Rosenberg, sensors product line manager at Balluff Inc.

Rosenberg explains how the technology works: "All background suppression sensors use triangulation of light to determine target presence based on distance. The sensor emits a beam through a collimating lens to the target. A portion of the reflected light is delivered back to the sensor through a focal lens onto an electronic receiving element called a position sensitive device (PSD). The target's distance from the sensor determines the angle at which the light travels to the PSD, and thus, the point where the light hits along the length of the PSD. The PSD delivers different resistance values to the microprocessor depending upon the light contact point, while the microprocessor determines the optimal trigger threshold.

"Until recently, there were essentially two methods of target range adjustment for BGS sensors, both manual. Sensors used either a potentiometer to adjust range electronically or a mechanical adjustment screw that changed the angle of a pivoting receiver/lens assembly to the correct cut-off point. New microprocessor-based sensor technology with advanced programming has taken manual adjustment completely out of the equation, allowing sensors to automatically determine the optimal trigger point - while ignoring background - even with a moving target."

Balluff's "one-button, sub-miniature BOS 6K sensors can learn the optimal trigger point even with the target moving at full production speed, eliminating the need to access hidden sensors or manually jog the machine into position," says Rosenberg. "These sensors combine the flexibility of background suppression with speedy self-teaching setups to provide the best of both worlds for quick and accurate position sensing for assembly, packaging and printing industries."