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Capacitive sensors are mostly known for their usage in interfaces for consumer products such as mobile phones. This technology has become more and more important in various industries such as household appliances, automotive interiors, and industrial applications. It enables:
Product design: Touch sensors allow freedom in design as conventional mechanical buttons and sliders can be replaced.
Durability: Capacitive sensors do not contain moving parts like mechanical input devices.
Gapless design: Gapless housings are more likely to withstand rough environments or enhance performance in clean environments.
Cost: The complexity of housing design and manufacturing is reduced significantly.
All applications are based on the principle of detecting the change of capacitance when an electrode is touched by a human finger.
Capacitive sensing is the process of detecting a change in an electrical property of a dielectric material by measuring changes in capacitance. It is a non-contact method of sensing; thus, it does not require any mechanical parts or parts that would require contact with the object being measured. Capacitive sensing is divided into two types: active and passive. Active sensing involves an electronic component such as a sensor or amplifier to detect small changes in capacitance. On the other hand, passive sensing relies on some simple circuitry and no additional electronics.
Capacitive sensing is the process of detecting a change in an electrical property of a dielectric material by measuring changes in capacitance. It is a non-contact method of sensing; thus, it does not require any mechanical parts or parts that would require contact with the object being measured. Capacitive sensing is divided into two types: active and passive. Active sensing involves an electronic component such as a sensor or amplifier to detect small changes in capacitance. On the other hand, passive sensing relies on some simple circuitry and no additional electronics.
Capacitive sensors are implemented in applications where non-contact data gathering is needed, such as in the industrial and medical fields. They are also being used in consumer products to replace switches and touchpads.
Fast Response
Less Expensive than other sensors
Small
Wide range of applications
Capacitive sensing is the process of detecting a change in an electrical property of a dielectric material by measuring changes in capacitance. Capacitance is the ability to store an electric charge. A parallel plate capacitor consists of two electrodes separated by an insulating medium. The electrical property can be measured by a change in the strength of an electric field applied to the object, which will result in a measurable change in capacitance. This change is measured through a device such as an oscilloscope or multimeter. The first capacitive sensor developed in the 1800s was a pair of brass cylinders, which were placed on either side of an electric field. Subsequent contributions to the field of capacitive sensing came from various electrical conductors. In 1900, the first commercial capacitive sensor was developed by the American inventor, Harry Brearley. He created the torsion balance sensor, one of the most common capacitive sensors in existence today. The development of active and passive capacitive sensors allowed for increasing levels of accuracy and versatility, paving the way to a myriad of applications in robotics and other industries such as telecommunication, medical devices, and automotive applications.
The underlying equation for the capacitance is:
Where,
C = Capacitance in Farads
ε = Permittivity of dielectric (absolute, not relative)
A = Area of plate overlap in square meters
d = Distance between plates in meters
Capacitive touch sensor
Capacitive proximity sensors
Capacitive switch
Capacitance measuring instrument
1. No wear
Unlike other sensors, capacitive sensors do not require physical contact with the object being measured, thus ensuring that the contacts and sensor are not worn out. This helps extend the life span of the sensor.
2. Compact
Due to their small size, capacitive sensors can be integrated easily into a housing and can use additional sensing technologies to improve the accuracy of detection.
3. Broad applications
Capacitive sensors have applications in various fields, such as robotics, automation, consumer products, human machine interfaces, and handheld devices.
4. Low cost
Capacitive sensors are often less expensive than other sensors because they do not require moving parts. Furthermore, they have great flexibility in manufacturing since the minimum requirement for them is simply a conductive area. Additionally, this reduces complexity of the housing. This saves money in design and manufacturing.
1. Sensitive to environmental changes
2. Sensitive to water on surface (false positive)
3. Needs more advanced software to compensate for false positive triggering
4. Can lead to problems with respect to EMC compliance
A capacitive sensor functions by detecting altering capacitance of a nearby object. When there is an applied electric field, the capacitance of the object changes. The sensor then measures this change in the capacitance and reports it back to a receiver. If the electric field is removed, then the capacitance of the object decreases. The sensor then reports that decrease to the receiver. The receivers use this information to determine the change in capacitance based on the time of the change.
Capacitive sensors are capable of detecting changes in capacitance. This is the principle behind how they work. The accuracy of a capacitive sensor comes from its ability to accurately report this change in capacitance caused by an applied electric field. They are thus very sensitive and easily affected by other elements like temperature and humidity in the environment. This means that they cannot be used outdoors as they will be affected too much by the elements. They also cannot be used in harsh environments that make them fragile, such as high temperatures or humidity.
Capacitive sensors are used in various medical devices, from defibrillators to cardiac monitors. They measure if the device is positioned correctly and provide feedback to the medical staff. Engineers can use the information provided by these sensors to determine what adjustments should be made to the device to improve its operation.
Capacitive sensors are used in modern smartphones, tablets or laptops. They can identify the positioning of the human finger on the screen and enable gesture recognition.
A capacitive moisture sensor works by measuring capacitance changes caused by the changes in the dielectric. It does not measure soil moisture directly (as pure water does not conduct electricity well), instead it measures the ions that are dissolved in the moisture.
Capacitive sensors are used as a manual button replacement. In this application classical button switches with moving parts are replaced by a capacitive sensor based on printed electronics which detects the human finger and enables smart switching.
Capacitive sensors can be integrated into industrial robots or machinery to detect objects for switching. They are easier and cheaper to integrate into automation solutions than some of the other often used sensors.
Proprietary force sensors - plyon®’s thin and durable sensor architecture differentiates itself with its excellent signal integrity under bending - the perfect fit for the application
One of the best innovations in resistive sensing come from tacterion. Their new sensor is called plyon®, which enables you to apply resistive and capacitive measurements to give you the best of both worlds. It is thin and durable, and it provides a simple interface to process its signals relatively easily, which is one of its major advantages. The Plyon sensor is quite inexpensive and has great characteristics such as its TrueZero capability, meaning it is flexible and does not lose signal integrity on bending up to a radius of 1 cm. You can integrate this sensor into flexible screens, making it perfect for integration in your applications.
The other great benefit of this technology is the data processing capability you get. The electronics interface is quite easy to use, meaning you won't have to worry about the signal processing side of the sensor. You can integrate it into your robotics, hand tools, touchscreens, and even your automobile. There is no limit to what you can do, and it will be dependent on your imagination. Best of all, these sensors are easy to manufacture and quite affordable, which means you don't have to increase unit costs, and you don't have to worry about how much it will cost to add next-level tactile technology to your device.
The final benefit of this device is how robust it is. Traditional resistive sensors can be affected by humidity, moisture, and other contaminants on the surface. This typically degrades performance, meaning you get outputs with more errors. However, the plyon® sensor includes technology to read signals accurately while dealing with the problems from nonideal environmental conditions. Moreover, the sensor is robust enough to also resist very high amounts of strain much above its sensitive range before they are damaged.
The signal processing capability of tacterion’s electronics and software is also extremely effective. It even adds the power of artificial intelligence and machine learning as well as traditional signal processing algorithms to enable personalization on a level never seen before. It makes resistive sensors even smarter, and they are perfect for the future of modern smart devices that will need the benefits you get from machine learning and artificial intelligence.
tacterion was founded in 2015 as a spin-off of the German Aerospace Center.
The unique force and touch sensor technology plyon® was developed as a sensor-skin for robotics which provides the sense of touch to products and machines. With a team of world class engineers, software developers, data scientists and industrial designers, tacterion develops smart surface solutions and smart components to enable the next generation of interactive and responsive products in the field of interactive handlebars, industrial robotics, and consumer electronics. Together with its clients tacterion enables the tactile internet of the future.
