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Honeywell’s MPR MicroPressure Board Mount Pressure Sensor.

It can be relatively easy to introduce a board mount pressure sensor to the market. In fact, over the last few years, several companies have introduced low-performance, unamplified sensors to address high volume opportunities.

However, modern applications demand so much more than a cheap low-performance sensor. Design cycles don’t allow for designers to do all of the extra work needed to make a useful measurement starting from a low accuracy, extremely variable, unamplified sensor. What they really need is a complete, accurate and reliable pressure measurement. However, it can be an expensive and lengthy process to develop a fully amplified sensor that brings value to the market.

To justify the investment, a sensor must address multiple applications. Of course, fully meeting the needs of multiple applications adds further complexity to the development of a new sensor. Thankfully the designers at Honeywell were able to draw on decades of experience in developing state of the art sensors and production techniques to develop the MicroPressure board mount pressure sensor. Honeywell’s other recent pressure sensor families are designed to address the needs of high end industrial and medical applications such as Ventilators, Diagnostic and analytical equipment, Chromatography and alcohol breathalysers to name but a few. However, the MicroPressure is developed specifically to address very high volume applications such as white goods, small appliances, Non-invasive blood pressure machines and other home-based medical equipment.

Driving the need for a pressure sensor tailored for these markets are megatrends like energy efficiency, the move towards smarter machines, IoT, wearables and the need to differentiate products in an increasingly competitive marketplace.

Smaller – Better – Low Price

Smaller

The first thing you notice about MicroPressure is that it is small. At 5mm x 5mm, we believe it is the smallest ported general purpose sensor around. There is no doubt that board space ends up being a precious commodity in any design so having a small sensor that does not need any external amplification and can communicate digitally directly with the procession is always an advantage. Size can become a critical design consideration in some applications. For example, devices are increasingly worn by the user. Imagine the benefit of a much smaller pressure sensor in a negative pressure wound therapy machine. Where previously the sensor might have to be connected to the patch via tubing, MicroPressure is small enough to mount directly in the patch. When you consider the availability of small piezo-based vacuum pumps and the ability to put a processor virtually anywhere, it is easy to imagine a totally self-contained single-use wound therapy patch.

In consumer small appliance applications, the clue is in the name, small appliances are getting smaller and increasingly designed for aesthetics leaving less room for the electronics. At the same time, customers are looking for greater and greater sophistication from the appliance and this often requires more electronics, including sensors. If we consider measuring process pressure in a tank or pipe within a small appliance, a MicroPressure sensor could be mounted on a flexible PCB. This could then allow a very space efficient process connection using an O-ring interface. This could mean that the sensor measurement takes virtually no additional space to implement.

In white goods, very low-cost electromechanical pressure sensing solutions are available and universally used in washing machines and dishwashers. These are effective and reliable but do require special mounting brackets, clips and tubing. A MicroPressure sensor could be PCB mounted with tubing run to it, or potentially mounted directly on the outer drum of a washing machine. The MicroPressure sensor is, of course, liquid tolerant.

Better

While Honeywell made the sensor as small as possible, we still use a high-performance sense die and high-resolution ASIC. As a result, the user has 13 effective bits of resolution and, after zeroing, 1.5% accuracy. This is pretty impressive performance considering most general purpose sensors on the market have lower performance than this in a much larger package and at a higher price. But why does a designer of high volume consumer products care? A great accuracy allows a greater degree of control of the designer’s product. This means that the product’s processes can be run more efficiently. Maybe this means that the machine will use less power or will be quieter or that your coffee machine will produce a perfect cup of coffee every time. Consumer product rating companies and the ready availability or consumer opinions on social media means that a machine that performs better is recognised quickly, is more successful and can command a higher price.

High performance in a small sensor can also be a game changer in that it may enable products that had been priced out of the mass market to be produced at much lower costs than before. One example is spirometry, the measurement of lung function. Spirometers measure the rate and volume of a patient’s breath. Spirometry is helpful in assessing breathing patterns that identify conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD. In the past, highly accurate spirometry machines where only available in clinical facilities. An asthma sufferer could obtain a mechanical spirometer for regular use at home. However, accuracy could be highly dependent on correct usage and monitoring of long-term lung performance depended on the tedious job of noting the measurements and handing this data over to the doctor. However, accurate electronic spirometry requires sufficient resolution, stability and accuracy from the sensor. The lack of low enough priced high enough performing sensors limited the availability of home-based spirometers. MicroPressure, however, enables low-cost spirometers to be produced that are affordable enough for home use. Regular, reliable testing at home with data delivered over the cloud direct to the doctor can improve the ability to treat the patient and improve quality of life.

Low Price

Does price really matter when a sensor is this small and has this performance? Oh yes, price always matters. The MicroPressure sensor was designed for low cost of production without sacrificing performance. It means we bring big sensor performance at a low price. Designers can reduce the cost of designs that already use a pressure sensor by switching to MicroPressure. More importantly, the economics of pressure sensors has changed with MicroPressure. It is now economical to integrate a pressure sensor into designs that may have previously used a suboptimal solution for pressure detection or did not detect pressure at all.

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26 Jan 2018, 8:49