NFC Sensors

What are NFC sensors?

Basically, NFC technology offers the possibility of exchanging data without contact. Based on RFID, a radio transmission is used for this purpose. In contrast to RFID, the transmission range of NFC is limited to 1-4cm. 
 
Sensors that collect environmental and process data play an important role in countless applications. These include areas such as smartphones, home and building automation, autonomous driving and other IoT applications. Compared to other sensors (e.g. RFID sensors), NFC sensors are a cost-effective way to develop sensors, as NFC can be read with any modern smartphone today. 
 
Conventional sensors are usually connected via sensor cable or data cable to supply the sensor with power and read the data. With NFC sensors this cable connection can be omitted. NFC can be used in two ways: Firstly, to exchange data with the sensor without contact, thus replacing the data cable. Secondly, NFC radio waves provide the necessary energy for activating and generating the sensor data (energy harvesting), thus enabling a cable-based energy supply. 
can be waived.
 
In summary, NFC sensors are sensors that can be addressed via the NFC interface. In the following, a distinction is made between active and passive NFC sensors and some examples are given.

Functionality and differences NFC sensors (active / passive)

(Semi) - passive NFC sensors operate without their own energy source (battery) and are powered by the antenna alone (energy harvesting). The current provided by energy harvesting depends on the field strength and antenna size, but is typically limited to 5 mA with an output between 2 - 3 V for a magnetic field of the order of 3.5-5 A/m. The sensors used must therefore be correspondingly efficient. This type of power supply also means that the sensors are only activated and collect data at the time of readout - i.e. the value currently present at the sensor and typically no historical data.
 
Active NFC sensors use an energy source that can be used to collect and store sensor values. Data is usually stored on the NFC sensor cyclically, i.e. at certain intervals, in order to save energy. The NFC interface is used here to read out the data values that have been recorded and stored by the sensor. 
 
A mixed form would be the semi-passive mode, in which the sensor switches to the appropriate mode after the battery has been discharged. The data is then temporarily stored and can be read out when the user activates the sensor.

Types of NFC sensors

NFC temperature sensor shows 25 degrees Celsius

There are various types of sensors that use NFC communication to transmit and provide data.
 
We use so-called IC sensors every day quite unconsciously: IC sensors are built into all common smartphones and measure e.g. volume or an approach to the screen. For example, the smartphone screen automatically locks itself when the device is held to the ear for telephoning (proximity sensor). 
IC sensors can also be outsourced in the form of NFC sensors. The greatest challenge here is the elimination of the energy source. In such a case, NFC sensors can receive energy from an active communication partner or a battery through the electromagnetic field generated by NFC. An intelligent power management system ensures that the energy is used efficiently and only consumed when necessary (low-power modes). These include, among others:
 
- Image sensors
- Accelerometers
- Inclinometers
- Proximity sensors
- Noise sensors
- Differential and absolute pressure sensors 
- Colour and light sensors
- Biometric sensors 
- Noise sensors
 
The type of sensor determines whether an active or passive version is more practical. For example, a passive accelerometer would be of limited use because it only provides the value that is currently available and not a curve over a period of time. In contrast, temperature sensors can also be passively useful if the current temperature is read out. 

Application examples of NFC sensors

The advantages of the wireless connection of NFC technology will probably become more and more popular in the future, especially at industrial interfaces. The advantages of fast, wireless and secure connectivity saves time and money. Possible applications are in process monitoring. For example, an active NFC temperature sensor can be used to monitor the temperature profile of a supply chain.   In general, active NFC sensors are always a good choice when a certain climate or pressure needs to be controlled over a longer period of time (e.g. over- or underpressure rooms). Passive NFC sensors, on the other hand, are suitable for taking quick snapshots of the current environmental conditions and are only supplied with power at the time of measurement. 
Summary and outlook
NFC can make many applications in medicine, health and fitness, IoT and consumer electronics more convenient and easier. In addition, NFC technology can merge these areas, for example by making industrial NFC sensor technology readable by smartphones and eliminating the need for a special module. With NFC, connection establishment is universal and not dependent on specific cable connections or proprietary protocols.

Summary and outlook

NFC can make many applications in medicine, health and fitness, IoT and consumer electronics more convenient and easier. In addition, NFC technology can merge these areas, for example by making industrial NFC sensor technology readable by smartphones and eliminating the need for a special module. With NFC, connection establishment is universal and not dependent on specific cable connections or proprietary protocols.

Further information about NFC

Erstellt: 2020-04-28 / Aktualisiert: 2020-08-06 2020-04-28 2020-08-06