PRODUCT UPDATE
Focus on suppliers of sensors
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Introtek International
Introtek International (Edgewood, NY, USA) supplies drip chamber sensors that use patented pulse-type ultrasonic technology to provide reliable noninvasive air-bubble detection. Suitable for use with soft-bodied drip chambers or large-OD tubing, the firm’s drip chamber level sensors can handle conditions such as relaxation, slippage, and vibration that would normally cause false air alarms. The sensors are designed to meet OEM form, fit, and functional specifications, eliminating or greatly reducing many of the variables that can negatively affect the performance of amplitude and continuous-wave-based sensing systems.
The company also offers blood component sensors that are capable of optically detecting as little as 1% of blood in a saline-filled tube. The sensor works by comparing a specific amount of light absorption by haemoglobin to a calibrated threshold. The sensor is designed to perform colourimetry on clear plastic tubing used in dialysis and other medical applications. A digital or analogue output can be provided to indicate the presence of a specific precalibrated threshold of blood content in dialysate, plasma, or water. A minicontroller is used to manage and validate the resulting electrical signals.
Other sensors are suitable for various medical devices that involve apheresis, autotransfusion, blood processing, drug delivery, haemodialysis, perfusion, and infusion. Although the company offers a line of standard products, approximately 80% of the firm’s sensors are tailored to customer specifications.
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Elettrotec
Compact electro-optical devices with built-in solid-state switching electronics are designed for liquid-level monitoring applications. Available from Elettrotec (Milan, Italy), the sensors use optic technology to detect the presence or absence of a fluid directly. They offer ±1-mm repeatability and broad liquid compatibility.
The sensors can be used for high-, low-, or intermediate-level detection in tanks. Installation is accomplished through the top, bottom, or side of the tank. With small bodies, no moving parts, and minimal prism intrusion, the SEL-series sensors are suited for medical applications where dependability and space conservation are critical requirements.
Sensortechnics
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Accurate gauge or absolute pressure measurement between 400 mbar and 7 bar is provided by a series of uncompensated, uncalibrated pressure sensors. Available from Sensortechnics (Puchheim, Germany), HPX-series sensors deliver ratiometric millivolt output signals and feature a good price-to-performance ratio.
With an operating temperature range of –40° to 125°C, the devices are suited for use with medical equipment and a wide range of demanding high-volume applications involving dry air and noncorrosive gases. The series is available with six-pin DIP housings for through-hole assembly or eight-pin SOIC packages for surface mounting.
The company supplies an array of other pressure sensors and custom systems to OEMs worldwide.
Fiso Technologies
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Miniature fibre-optic sensors from Fiso Technologies (Québec City, QC, Canada) incorporate a micromachined silicon diaphragm membrane, which acts as the pressure-sensing element. It is bonded on a cup-shaped glass base, which creates a Fabry-Pérot cavity that modulates the signal with low coherence interference. The sensor is connected to a multimodal optical fibre that acts as the light conveyor between the sensor and the signal conditioner. The wavelength-modulated optical signal is reflected toward the signal conditioner, which determines cavity length using patented white-light cross-correlation technology. Because of the electrically insulating nature of the fibre and sensor materials, the sensors are not affected by incident radio-frequency, electromagnetic, or microwave fields.
The sensors’ miniature size and the use of inert components permit in vivo and in situ measurements in restricted areas such as in small vessels and delicate tissues. With the increased development of minimally invasive surgery using instrumented catheters, the sensors reportedly fill a growing demand for miniaturized, reliable, and accurate sensors for temperature and pressure measurement in healthcare fields such as cardiology, neurology, and urology.
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Priamus Systems Technology
Miniature cavity-pressure sensors from Priamus Systems Technology (Schaffhausen, Switzerland) are suitable for mould setup, and injection moulding, process monitoring, and process control. The patented design protects the sensors from side-load sensitivity loss. A hardware code provides all sensitivity information to adjust the amplifiers automatically. The sensors are available in two basic versions: one has an integrated thread in place of a mounting nut to facilitate installation; the other is small enough for sleeve installation.
