Pressure Sensors: The Design Engineer's Guide

Pressure sensors: 11 life-enhancing consumer applications

The things we use, carry and wear on a daily basis are growing in intelligence. More and more, our appliances are able to detect changes in their environment and modify their behaviour based on those changes. Pressure sensors are one of the technologies enabling smarter consumer electronics.

Adding a pressure sensor to a consumer device gives you an entirely new dimension to explore, and the information this provides can create an improved user experience, making your next product stand out from the crowd.
 

1. Keeping food fresher for longer with a partial vacuum

A recent innovation in refrigeration takes a step beyond cooling, and actually seals the inside of the fridge using a partial vacuum. By lowering the oxygen levels inside the fridge, food remains fresh for longer.
Pressure sensors are essential in this application, as they provide the feedback needed by the pump used to reduce the pressure in the compartment.
 

 

2. Making vacuum cleaners more effective and easier to maintain

Vacuum cleaners are becoming smarter, frequently by using pressure sensors. For example, by measuring minute changes in suction pressure they are able to detect the kind of flooring being cleaned and adjust settings such as power and brush height to suit. Pressure sensors also enable owners to be notified when a dust receptacle is full and when the filter needs to be replaced.
 

 
An example of how combining barometric pressure sensing with GPS can deliver more accurate altitude measurement than GPS alone (Source: https://users.ece.cmu.edu/~franzf/papers/baroaltitude.pdf )

3. Augmenting GPS in built-up areas

Many small devices now integrate GPS receivers that tell the device its position in three dimensions; latitude, longitude and elevation. Mapping software uses these coordinates to plot the device’s position on a rendered map.

In urban areas, GPS signals can be obscured or degraded by large structures, covered areas and tunnels. Technology is being used to restore at least one of the three datum points; elevation.

In absolute terms a barometric pressure sensor can be used to determine elevation and therefore augment the GPS signal. The argument is that by using the confidence level of both a barometric pressure sensor and GPS signal, a more accurate altitude measurement can be obtained. This can help the device to better determine its position in a mapped building based on its altitude, which in turn can deliver a more accurate location.

In the chart on the right, the research data show that an increased accuracy confidence level of 85% can be obtained using this sensor fusion technique versus GPS alone. Other sensors can provide an indication of direction and speed, allowing the device to estimate, with reasonable certainty, its position.

This technology is now being used to provide consumers with indoor navigation for shopping malls, airports and other large public spaces.
 

4. Forecasting hyper-localised weather

The use of home weather stations is increasing, as are online services that provide weather information, both of which are contributing to a trend in highly-localised weather forecasting. Inside each weather station sits a barometer; a pressure sensor detecting the smallest variations in atmospheric pressure.

Atmospheric pressure changes can be interpreted by the weather station or its cloud-based algorithm, to determine the presence and movement of storm fronts, and thus predict the likelihood of rain.
 

5. Purifying the air and water

As the population density in metropolitan areas continues to rise, the level of air quality is becoming a greater concern. Many people now choose to use an air purifier, which uses high efficiency particulate air (HEPA) filters to trap airborne contaminants.

Over time, the filters become laden with contaminants and need to be cleaned or replaced. A gauge or differential pressure sensor capable of measuring ultra-low pressure differences can detect when this becomes the case and alert the user.

Pressure sensors can be used in a similar way to monitor filters in water purifying systems, and indicate when they need to be replaced.
 

6. Washing clothes more efficiently

Washing machines are a major home energy consumer, so making their use more efficient is a key focus for consumers and manufacturers alike. As more homes in Europe move onto metered water connections, reducing overall water use per load is also of significant interest.

By using pressure sensors to precisely regulate the amount of water required, significant environmental savings can be made.
 

7. Making better coffee

From simple coffee ‘pod’ machines to more complex bean-to-cup systems, there are two key principles in achieving the perfect brew: temperature and pressure. In fact, pressure is so key to the process, the word ‘espresso’ literally means ‘pressed out’.

Absolute pressure sensors designed for harsh environments are used in these machines during the brewing stage, and in the cleaning process that follows it in higher-end coffee makers.
 

8. Making cooker extraction more effective

Extraction fans are now a common feature in most kitchens, and pressure sensors help keep them working. To work most efficiently the right amount of negative pressure needs to be produced at the hood, achieved by driving the fan at the correct speed. A pressure sensor is used to measure the negative pressure produced, and in turn control the fan.
 

 

9. Measuring altitude in extreme sports

For sports enthusiasts, barometric pressure sensors can be used to measure the height above ground or below sea level, in both air and water. These sensors are used by the likes of skydivers and scuba divers. Piezoresistive MEMS sensors are a popular choice in the latter application due to their size and accuracy.
 

10. Tracking stairs taken on top of your 10,000 steps

Some fitness bands and wearable devices use pressure sensors to calculate the change in air pressure and correlate that to height differences. Combined with readings from an accelerometer, the devices can determine when you’ve chosen the stairs over the lift and award you the extra points that come with healthier option.

The gamification of daily activity continues to grow and can now be more accurately measured - and rewarded!
 

11. Detecting falls in assisted living devices

Air pressure measuring principles are now used in patient monitoring and assistive living solutions, where a sudden rapid change in altitude can indicate a fall.

Pressure sensors in this application space will typically be capable of measuring changes in air pressure in hundredths of a milli-bar with an accuracy of 2mbar or better. That means they can register an altitude change of around 10cm, easily accurate enough to determine if a patient is on the floor.

An alert will be sent to the relevant service provider (or family member) to enable them to contact the wearer immediately and/or send assistance as appropriate.

As the examples above illustrate, modern life is increasingly reliant on pressure sensing devices to deliver a wide range of features and functions in automated devices. As lifestyles continue to evolve, new applications are also using pressure sensors to deliver key functionality.
 

What else are pressure sensors used for?

Find out more in our articles on applications in automotive, building automation, consumer and wearables, medical and industrial applications.

Pressure sensors: 10 innovative automotive applications.

Pressure sensors: 8 life-saving medical applications.

Pressure sensors: 8 building automation applications.

Pressure sensors: 3 applications enabling smart factories in Industry 4.0.

Looking for more on pressure sensor technology? Check out the further chapters of this guide below, or if you're pressed for time you can download it in a PDF format here.

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Pressure Sensors Chapter 1 GBL

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Chapter 1

How pressure sensors work

An introduction to pressure sensors covering the different types, how they work, their function, construction, and what to consider in your design choices.

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Chapter 6

The core pressure sensor technologies

What’s the difference between the different pressure sensor technologies? And how do you know which one to use?

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Chapter 3

The different types of pressure sensors

Discover how pressure sensors vary according to the type of pressure measurement, sensing principles, output signal, media, MEMS technology, mounting and more.

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Chapter 7

Pressure sensors for different media types

An in-depth guide to pressure sensors for different media types. Learn about the technology, applications, different options, their specifications and their limitations.

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Chapter 4

Pressure sensor output signals

Sensors, transducers, or transmitters? The right selection is important for your application. So what's the difference and how do you choose between them?

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Chapter 8

Pressure sensing in harsh environments

An in-depth guide to pressure sensors for harsh environments - designing for extreme temperatures, high pressure, and corrosive and dynamic environments.

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Chapter 5

Types of pressure measurement

What’s the difference between absolute, gauge and differential pressure sensors? And how do you know which one to use?

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Chapter 9

Understanding specifications

Explore the datasheet and the different factors affecting the accuracy of pressure sensor readings. Discover how to make the right choice for your application.

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