What the growing pressure sensor market means for electronics
The pressure sensor was one of the first to realise the possibilities of micromechanical systems (MEMS) technology. Designed to support the introduction of computer-controlled fuel-injection systems, the MEMS pressure sensor became a mainstay of the market and a fundamental component for automotive manufacturers in the early 1990s.
Growth in the use of pressure sensors since then has been steady but analysts such as Markets and Markets believe the broadening of applications for the technology is leading to a higher rate of adoption. The result is a compound average growth rate of 5 per cent until 2023 from a base of approximately $8.3 billion this year.
In the automotive sector, the use of pressure sensors has spread far from the initial application for absolute pressure sensors inside the engine manifold. After helping to improve the fuel efficiency of petrol and diesel engines, sensors to detect changes in pressure moved into the tyres. There they watch out and warn of rapid changes in inflation that may point to a puncture.
Airbags now routinely use pressure sensors. Whereas front-facing driver and passenger airbags can use sudden changes reported by accelerometers to trigger inflation, those devices are ineffective for detecting side impacts. Pressure sensors can pick up the sudden change in air pressure as the cavity inside the door begins to collapse from a broadside impact.
Automotive tyre monitoring and fuel injection applications generally call for absolute pressure sensing. Research indicates the highest growth in pressure sensors over the next few years will be for differential sensors. Part of the reason for the growth is the increasing use of pressure sensors in medical applications. The differential design lends itself to use in ventilators for people with reduced lung function and in detecting fluid levels in catheters.
Although there has been a steady demand for advanced electronics in bedside equipment, growth in medical applications is set to increase because of the proliferation of mobile healthcare devices. Hospitals want to be able to discharge patients for home-based care earlier than has been possible in the past. Smart electronics devices make it convenient for patients to keep track of conditions and alert medical professionals if problems appear. The constant flow of data from respiratory and fluid measurements make it easier for nurses and doctors to gauge progress.
As sensor technology continues to benefit from the miniaturisation and cost reductions made possible by MEMS, use of electronic pressure measurements will move into devices that used to be extremely simple. One application is the smart inhaler: a device able to deliver precise amounts of drugs to control chronic conditions such as asthma.
A further source of rapid growth in pressure sensing is for devices that use optical techniques. The MEMS devices used in many automotive and medical applications are based on the silicon diaphragm that records deflection due to changes in pressure. Some employ the variation in capacitance between the diaphragm and a nearby conductive surface. Others employ a strain gauge or piezoelectric element. Optical devices, instead, employ fibre Bragg gratings. These gratings measure the deflection in a glass fibre caused by changes in pressure on it.
The advantage of optical sensing is that the part of the fibre used for sensing can be placed some distance from the readout electronics. It is also highly suited to conditions where other sensors would convey inaccurate readings due to large temperature excursions and electromagnetic interference. As a result, optical sensors are useful in harsh environments, such as industrial processing, as well as smart-city applications where optical sensors under the pavement or road can monitor the number of travellers passing overhead.
Although there is a bright future for dedicated sensors, multifunction products that combine different MEMS elements in one device will help promote the use of pressure sensing in consumer applications. The ability to measure air pressure provides greater position sensing accuracy for handheld devices such as smartphones and tablets that already contain accelerators, gyroscopes and GPS receivers. As the advances in MEMS and related technologies continue, we can expect many more applications to drive further growth.
Are you developing a new device or application that requires pressure measurement? Read the design engineer's guide to pressure sensors and explore a range of additional pressure sensor resources to help you find the right solution for your design. Alternatively, if you’re ready to take the next step, contact our team of technical specialists who are on hand to discuss your design and assist with product selection.