Battery-free sensing · Custom sensors
CustomCustom battery-free sensors
Our evaluation boards are examples. If the sensor you need is not in the catalogue, we design it: the radio and the energy harvesting, the electronics around your sensor, the firmware and the software that reads it.
Our team has been doing it for more than 20 years: at Tecnun and CEIT, then at Farsens, and now at Kliskatek.
What our team has made battery-free
Weight (load cell)
A load cell on a weigher, 0 to 5 kg with ±0.05 kg accuracy, read over UHF RFID.
Deformation (strain gauges)
Strain gauge tags for deformation monitoring, read over UHF RFID.
Pressure
Pressure and temperature tags, 0 to 14 bar, read over UHF RFID.
Contact temperature
NTC probe tags, −30 to 105 °C with ±0.5 °C, read over UHF RFID (EVAL-SID-CTN).
Temperature and humidity
Ambient temperature and relative humidity, over UHF RFID, Bluetooth LE and NFC.
Motion and magnetic field
3-axis accelerometers and magnetometers, over UHF RFID and Bluetooth LE.
Ambient light
Light sensor and light-dependent resistor tags, read over UHF RFID.
Resistive sensors
A generic resistance reader, used for soil moisture among others, over UHF RFID.
Capacitive sensors
Capacitance measured from the harvested energy alone.
Contact status
The state of up to five contacts in one tag, over UHF RFID.
Latching relays
A relay that switches 250 V AC at 2 A and stays put with no power, driven over UHF RFID.
LEDs and e-ink displays
Tags that light an LED (pick to light) or update an e-ink display from the reader’s field.
Sensors we can connect
- Digital sensors: SPI and I2C.
- Resistive sensors: NTC thermistors, light-dependent resistors, soil moisture.
- Bridges: strain gauges and load cells.
- Capacitive sensors.
Outputs, with no battery
- Latching relays: they switch and stay put with no power.
- LEDs: pick to light, or a sign that the tag is being read.
- E-ink displays: they keep the image with no power.
It can compute, not just measure
Every tag has a microcontroller. Today it reads the sensor and prepares the data, but it can do more on the tag itself: average or filter readings, compare them with a threshold, count events, analyse a signal, and send only the result.
What it can do depends on energy. The tag stores what it harvests from the radio field in a capacitor, and every operation spends part of it. More processing needs more energy, and more energy means more time charging before the next measurement. Choosing that balance is part of the design.
The trade-off, explained
Inside a battery-free sensor: power path, storage and duty cycling
Battery-free sensor sampling rate: what your power budget actually allows
Three ways to read it
Step by step, each one paid and decided
Feasibility study
Typically four to five weeks: whether your sensor works without a battery in your environment, with which radio and at what range.
Prototype
Working units of your sensor, tested in your application.
Industrialisation
Certification and the first series, when the prototype has proved itself.
Frequently asked questions
Can you make a battery-free strain gauge or load cell sensor?
Yes. Our team has built a battery-free load cell on a 0 to 5 kg weigher with ±0.05 kg accuracy, and strain gauge tags for deformation monitoring, both read with standard UHF RFID readers.
Can a battery-free tag drive something, not just measure?
Yes. Powered only by the reader’s field, our team has driven latching relays that switch 250 V AC at 2 A, LEDs and e-ink displays.
My sensor is not on the list. Can you still make it battery-free?
Usually, if it is digital (SPI or I2C), resistive, a bridge or capacitive, and its energy per measurement fits what the radio field delivers. When it does not fit, we say so. The feasibility study answers it for your sensor, your environment and your read range.
Which radio should my sensor use?
UHF RFID if you already have or want standard readers and read ranges of metres; Bluetooth LE if any phone or gateway should receive the data, with a UHF transmitter supplying the energy; NFC if a person reads it by tapping it with a phone.
How far can a battery-free sensor be read?
Our UHF RFID and Bluetooth LE boards reach about 5 metres with a 2 W ERP setup; NFC works at up to 2 centimetres, depending on the phone or reader antenna. Your environment changes these figures: metal, water and mounting position do.
Can the tag process the data, not just send it?
Yes, within its energy budget. Every tag has a microcontroller: besides reading the sensor, it can average, filter, compare with a threshold, count events or analyse a signal, and send only the result. The more it does per measurement, the longer it has to charge in the field before the next one. The feasibility study sizes that balance for your application.
Is the evaluation kit the product?
No. The evaluation kits are examples to test the technology on your bench. Your sensor is designed for your measurement, your enclosure and your volume.
More on what custom battery-free sensors can measure: Beyond temperature