Review

Whether involving size, performance or application, sensors and transducers are registering impressive gains, with the advances affecting most if not all of the long list of devices classified as sensors. From commonly used detectors, such as accelerometers and proximity, pressure and temperature sensors, to new categories, such as biometric and photo sensors, designers are being presented with a raft of new products with which to perform sensing and detection functions for their industrial, commercial or consumer products. Here is a sampling of interesting new sensors and transducers from 2003.

A novel addition to the highly active field of biometrics is Authentec's (authentec.com) AES2500, a fingerprint slide sensor that is said to allow fingerprints to be read below the skin's surface, thereby eliminating recognition failures related to contaminates. With a 192 x 16-pixel sensor array measuring just 9.75 mm x 0.81 mm, the device is small enough for use in PDAs and wireless devices. It operates on 2.4V with a finger sweep speed of 17 cm/s and draws less than 1 mA when detecting and less than 25 mA peak while imaging; standby current consumption is less than 10 µA.

Where RGB sensing is called for, TAOS (taosinc.com) offers a new device packing a digital-compatible interface. Housed in an 8-pin SOIC package, the TCS230 RGB sensor is said to be built on a unique light-to-frequency converter platform that allows resolutions of 10 to 12 bits or better per color channel without the need for A/D converters. Sensing is performed with a 64-photodiode grid arranged in four arrays, with each array dedicated to a single color: red, green, blue, and clear.

Microsemi (microsemi.com) has developed a PIN diode array for automatically controlling the brightness of flat panel displays with human eye accuracy. Housed in an 8-pin MSOP package, the LX1970 visible light sensor is said to work with virtually any display, whether employing fluorescent lamps or LEDs. No optical filters are needed. The photo sensor converts light to matching current source and current sink outputs, so design-ins can be as simple as adding a resistor.

Weighing in at a mere 0.2g and measuring just 2.8 mm x 5.7 mm, the Model 35C23 ICP accelerometer is designed to perform shock and vibration measurements in space-restricted and weight-limited applications. Developed by PCB Piezoelectronics (pcb.com), the sensor generates a 5 mV/g output signal with a frequency response from 2 Hz to 10 kHz.

Omron Electronics (info.omron.com) is the developer of a novel sensor that can detect gas flowing in either direction. Targeting applications in fuel cells, chemical test chambers, and respiration monitors, the D6F can detect flow velocities as low as 0.005 m/s. Omron Electronics is also the source of a magnetic sensor that can measure the position and rotation of both ferrous and non-ferrous metals. The device 's depth of detection can be varied by changing the excitation frequency. Its sensing distance ranges from 0 to 1 mm. Applications are where low levels of changes in magnetism are encountered, such as in GPSs and vending machines.

Relative humidity levels from 10% or 20% to 90% can be measured by using HDK America's (hdk-america.com) HIS-06, a tiny, 7.0 x 4.0 x 10.5 mm sensor made of polypropylene. Containing a moisture-repellant, precision resistive membrane element sensitive to humidity, the radial lead, board-mountable devices are designed to change resistance (impedance) in response to surrounding changes in humidity.

—Joe DelGatto

Outlook

Revving Up A Host Of Applications
Over the next year, R&D efforts underway in the sensor industry are expected to trigger rapid growth in new application areas and spur increased use of these devices in existing markets. At the top of the list of application areas targeted for new sensors and transducers are automotive, biometric and surveillance markets. New sensors will play a crucial role in the creation of a host of new and/or improved features for products and systems associated with these markets—e.g., systems for alerting drivers of cars or trucks that they starting to doze off; portable medical instruments for use in the home; and systems for tracking traffic. And as to sensors and transducers based on established technologies, designers can look forward to a raft of new products that are smaller, smarter, cheaper, and more energy efficient than their predecessors. Manufacturers are also expected to launch more devices that integrate control circuitry with sensors.

—JDG