Article - April 2002
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Contact Sensors Losing the Battle against Non-Contact Sensors
Contact sensors are starting to become an "old-fashioned" way of measuring, detecting, and/or sensing any particular measurement. 

Daniela Carrillo, Research Analyst, Frost & Sullivan
Daniela Carrillo
Research Analyst,
Frost & Sullivan Sensors Group

In the sensors market there has been an increasing trend toward non-contact sensing technologies among some end user markets such as the automotive, medical, industrial and aerospace industries. This has been done in an effort to minimize costs, avoid wear and tear of sensors and to meet stringent reliability requirements. In this article I will discuss the advantages and disadvantages of non-contact and contact sensing technologies, as well as, some of the most important trends in these technologies.

The sensor industry is a highly dynamic and demanding one. As technology advances, customers are seeking more accurate, reliable, and durable sensors. Recently, contact sensor manufacturers are challenged by non-contact sensor suppliers. Although contact sensors have a price advantage, non-contact technologies are more durable and most importantly, provide accurate measurements. For instance, automotive manufacturers and the industry in general are placing ever-increasing demands on accurate sensor systems for applications such as wheel speed sensing systems, engine and transmission management, as well as power steering. In addition, such systems are also required for onboard instrumentation, fuel consumption and for the accurate calculation of any kind of positional and rotational position sensing. Therefore, the non-contact magnetic Hall Effect sensor is subject to stringent performance and reliability requirements in automotive applications.



Magnetic vs. Potentiometers 

Most of the magnetic sensors when applied to a device produce a mechanical contact, which typically causes the device to wear out in a shorter period of time. Hall Effect (HE) sensors are becoming increasingly popular among original equipment manufacturers (OEMs) in most industries because of their ability to detect the presence of a magnetic field near them, without making contact, leaving no room for friction. As a result, HE sensor devices do not wear out easily and have a longer life operation cycle. Also, an advantage of non-contact applications is that there is better protection against any type of contaminant agent. 

Another type of non-contact position sensor is the magnetostrictive linear position sensor, which also has a competitive position in the automotive industry. Magnetostriction is a property of ferromagnetic materials such as iron, nickel and cobalt. When placed in a magnetic field, these materials change size and/or shape. A magnetostrictive effect is caused by the interaction of an external magnetic field with the domains. There has recently been an important new development in magnetostrictive sensors: low-cost sensors for high-volume applications. 

On the other hand, there are the contact, linear potentiometric displacement sensors in which a rod/shaft (wiper) moves in correspondence with the object being measured. The wiper completes a circuit for a current flowing through a resistance track. The output resistance fluctuates depending on its location on the track and thus measures the object's position. Moreover, superior sensing technologies such as Hall effect and magnetostrictive sensors are hampering the growth of the market for the potentiometric displacement sensors in that, as the overall demand for position measurement expands, new customers are more likely to gravitate towards technologies other than potentiometric. 

Catalytic vs. Infrared 

First let me briefly talk about the properties of catalytic (or also called pellistor) gas sensors. These are the first commercialized types of contact gas sensors. The following are some of their applications:

Catalytic gas sensors are generally placed near the process pipe wall where the sample of gas is collected by convective flow or powered aspirator. Although catalytic gas technology is considered to be the established technology in detecting combustibles, however, the launch of infrared technology is expected to hinder catalytic market revenues. One of the reasons behind this is that catalytic sensors are more prone to poisoning from a contaminant than infrared sensors. The new and improved feature developments in infrared technology are anticipated to discourage end users from continued utilization of catalytic sensors. Additionally, the market age of catalytic gas sensor technology can be viewed as a disadvantage to prospective revenue growth. Although market maturity can provide a stable foundation for end users, many are opting to adopt newer technology in order to remain abreast of the competition. 

Thermocouple vs. Infrared 

Reliable Controls Thermocouples are one of the cheapest and easier to use type of contact temperature sensors. Because of the simplistic design of this sensor, it is also easy to manufacture. Thermocouples have many inherent qualities, which include their accuracy, wide temperature range, fast response, low cost and repeatability. While thermocouples are used in a wide variety of environments, the largest end-user applications involving the use of these sensors include: chemical/petrochemical, metals, food and beverage and semiconductor. 

With sensor manufacturers focusing on leading technologies, in this case infrared temperature sensor, thermocouples, the least technologically advanced electronic sensor, often is the last to receive funding for research and development. Thus, thermocouples are often sold based on historic end-user experience, not because a manufacturer is promoting these products. Manufacturers that only produce thermocouples are trying to determine what additional areas they can enter into in order to expand their product offerings, as demand for thermocouples becomes minimal. The thermocouple market is consider to be a quite saturated and a mature industry. 

However, infrared (IR) thermometers, which detect the infrared energy emitted by objects and materials and utilize this value to measure temperature, are becoming the non-contact temperature sensor of choice among end-user industries. Some of the advantages of modern IR temperature sensor design versus more traditional ones are the following:

Also, IR thermometers are useful for measuring temperature under circumstances where thermocouples or other probe type sensors cannot be utilized or do not produce accurate data for a variety of reasons. A unique characteristic about infrared thermometers is their ability to determine the temperature of an object without making physical contact with it. 

The principle of IR and its non-contact nature offers many advantages over other types of contact temperature measurement such as thermocouples. Temperature can be monitored now with minimal, if any, risk of contamination of contents which is extremely important in the food and beverage industry. Furthermore, IR sensors save time and money in situations where another type of contact sensor would require machines to be shut down. 

Unlike thermocouples, the IR temperature sensors market is in a development/growth stage. Increasingly, process engineers are turning to the latest infrared sensors to help them document temperatures in support of ISO 9000 and other quality control programs. The monitoring and documenting of process temperature is essential in many manufacturing operations. Recently, the demand for manufacturers to follow certification procedures such as ISO 9000, has spread to many industries as a way of building customer confidence in product quality, which is especially important for international suppliers. 

Show Me the Numbers 

After talking about the advantages and disadvantages of the different types of contact and non-contact sensor technologies and some of the major trends driving revenue growth, I will discus the revenue forecast in North America of these sensor technologies. As can be seen, Figure 1 depicts the revenue forecast for the contact vs. non-contact sensor market from 1999 to 2003. In 2000, the catalytic gas sensor market generated revenues that totaled $84.3 million and it is anticipated that by 2003 revenues should reach approximately $93.2 million. The IR gas sensors showed higher revenues than catalytic, which totaled $150.3 million in 2000. Since non-reactive infrared gas technology is becoming significantly popular in gas detection and prices are continuously declining, revenues are expected to increase and settle at $189.4 million in 2003. 

Revenue forecast for the contact vs. non-contact sensor market

As of 2000 the thermocouple market revenues were $131.9 million and are anticipated to slightly decline because of the emergence of new, competing technology like IR temperature sensors. By 2003 revenues should settle at $130.2 million. On the other hand, IR temperature sensors generated revenues of $160.9 million in 2000. This has increased approximately 10.5 percent from the previous year's sales of $145.6 million. By 2003, revenues are anticipated to increase to $216.9 million. This is mainly due to the continuous development in infrared technology and IR thermometers' expansion to new markets. Manufacturers have to continue looking for output and growth of industries such as metals, glass, paper and plastics, which is a possible way of gauging demand for IR temperature sensors. 

Last but not least, is the potentiometer market that in 2000 generated revenues of $33.6 million in the North America region. Despite potentiometric sensor suppliers' efforts to reduce the wear of their devices with new designs and materials, end users have begun to move toward non-contact measurement devices such as the magnetic position sensors. By 2003 revenues are anticipated to increase at very modest growth rates reaching revenues of $37.5 million. Magnetic position sensors (which include Hall effect and magnetostrictive) produced revenues of $273.3 million in 2000 and revenues are anticipated to increase by 2003, reaching revenues of $398.2 million. One of the factors that makes magnetic sensors more attractive than potentiometers is its low price which ranges from $2.00 to $15.00 per unit, while potentiometers are sold at $138.00 per unit. 

How Old Are You? 

There are some sensor technologies that have been around for quite a long time. There are still some manufacturers that are quiescent to adopt or incorporate new technology to their already established product line. Consequently, they are threatened by companies offering innovative products and further expanding their business to potential markets. Chart 1 illustrates the market age stage of the different non-contact and contact sensor technologies. Contact technologies including catalytic gas sensors, thermocouple and potentiometer have already reached a maturity level. While IR gas sensors and magnetostrictive sensors are enjoying a growing market with a high potential in some emerging end-user markets like automotive, food and beverage and medical among others. Infrared temperature sensors market is the youngest of all, which is still in a development stage. 

Chart 1 illustrates the market age stage of the different non-contact and contact sensor technologies.

Future Trends 

Contact sensors are starting to become an "old-fashioned" way of measuring, detecting, and/or sensing any particular measurement. Although, they still have some historical applications, there is a trend among end-users of adopting non-contact sensing technology in order to have more durable sensors and reduce replacement costs. Non-contact sensors provide end users with high accuracy, resistance to contamination and reliable measurements. However, some non-contact sensors such as infrared tend to be more expensive than traditional contact sensors, end users are becoming more aware of their vast capabilities. In other words, non-contact sensor's high price is compensated by its higher accuracy and reliability. In the sensors arena the quest for developing more reliable, accurate and value-added sensing devices is anticipated to continue in the years to come, especially as sensors are becoming smarter and smaller. 

For additional information on this and other sensors research, please refer to Frost & Sullivan's reports:
7729-32 World Magnetic Sensors Market 
7412-32 World Proximity and Displacement Sensors Market 
7862-32 North America Gas Sensor Market 7984-32 North America Infrared Sensors Market 
5922-32 World Temperature Sensors Market

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