RVmagnetics - MicroWire Sensing Technology

MicroWire sensors are magnetic. To sense them, we need to generate an AC magnetic field (triangual or other) with excitation coil. Unless present in noisy magnetic or electric fields, coil is powered with a few milliAmperes. The magnetic response from the MicroWires (with high sensitivity to temperature, pressure and position in the magnetic field), in terms of a magnetization change, is sensed with another pick up/sensing coil.

Output from the sensing coil includes signals from magnetic and electric noises present in the vicinity of the sensing coil during the measurements. Signal obtained needs to be filtered out of noises and also amplified.*

Filtered and amplified signal is digitalised in MCU (ARM chip) and ready for data post-processing in customer`s pre­ferred software.

We use ARM customized chip as a processing system. Coils are directly connected to the electronics, while electronics di­gitalize the received data, and through USB, or using Bluetooth / Wi-Fi / SigFox, … It can send the digitalised data where you need them for further processing.

Digitalised data output from electronics is further processed and calibrated using our tailor-made software for ARM chip. Calibrated values are transferred for further post-processing to clients preferred peripheral or software.?

To obtain local data – MicroWire (of length 1–4 cm) needs to be placed on / in the material. As the sensing system needs to be placed in the proximity of the MicroWire – within 10 cm range – measurements can be obtained even through other materials (even metallic, magnetic materials).

Glass-coated microwires are composite materials that consist of a metallic nucleus covered by glass shielding. They are prepared by drawing and rapid quenching of molten alloys and glass. They have unique properties in terms of the magnetization process as well as in terms of the mechanical properties. This makes them suitable elements for sensing various physical quantities in engineering applications.

Magnetic properties are mainly given by magnetoelastic interaction of magnetic moments with a distribution of mechanical stresses induced during production. Axial mechanical stresses arise as a result of drawing and rapid quenching of the wire. Radial and circular stresses arise from different thermal expansions coefficients of glass coating and metallic core. In addition, shape anisotropy is given by physical dimensions (diameter of the wire ∼1–40 μm, length of the wire ∼1–4 cm).

To conduct measurements, we use unique magnetic material – Bistable Microwire – for sensing the magnetic field and temperature/mecha­nical stress in a single measurement.

Temperature sensing and stress sensing are not affected by magnetic noise (even though the sensor is magnetic).   Measurement is very different from the one used in conventional magnetic sensor. Conventional sensor requires high permeability (for high sensitivity) and high saturation field (for high range). RVmagnetics sensor has permeability ~ 1 (like vacuum) and saturation field cca. 3 Oe.

We are able to measure pressure – pressure dependence of the switching field is perfectly linear within whole measured range – while the measurement is completely temperature independent. It also works vice versa – we are able to measure temperature – while temperature dependence of the switching field is perfectly linear within whole measured range – measurement is completely pressure independent.   For the sensing – for the easy demonstration – let’s use mobile phone sound card as an example. We need earphone output for producing the magnetic field (serves as the excitation coil) and microphone input to sense the signal (serves as the sensing coil).

There is no connection between the microwire and coils – Microwire can be place inside various materials and coil system detects a signal from the distance up to 10cm.

We transform the measured parameter (magnetic field, temperature, stress, or others) into the time (the output is not a voltage – it is the velocity of domain wall propagation). Hence it is better to used counter in ARM chip (here, the output is directly number/magnetic field) or FPGA or similar fast electronics instead of microphone (which has small sampling frequency ~7kHz). The higher is the time resolution, the higher is the accuracy of sensor.

• direct measurements : stress, temperature, magnetic field
• indirect measurements : bend, torque, pull, strain, position, flow, vibration, humidity
• operating temperature range : –273 to 600°C
• temperature measurement accuracy : 0.01°C
• sensor diameter : 3–70 µm
• metallic alloy nucleus diameter : 1–50 µm
• glass coating diameter : 2–20 µm
• sensor length : 1cm-4cm
• frequency of sensing coil : up to 50.000 times per second
• frequency of exciting coil : from DC up to 20 kHz (audiofreq.)
• Long term survival : 1000+ years
• sensor permeability : ~ 1 (like vacuum)
• sensor saturation field : cca. 3 Oe.
• operating pressure limit : none
• corrosion to alkaline and acidic environments : none
• contactless sensing : up to 10 cm distance
• low power consumption : mA on one single measurement

Power Consumption

mA on one single measurement Sensor is passive, power wired is only the sensing device (set of coils) Sensor is glass coated – provide protection from aggressive (acidic/alkaline) environment Sensor provides biocompatibility – no affecting X-ray or MRI

Sensor input and output

Input: temperature, pressure and magnetic field and other physical attributes we can convert to: position, el. current, humidity Output: is always digital, its data (AD converted)

How to collect signal

Sensor is magnetic, so we collect signal by magnetic induction. In the end its magnetic response of the wire to our sensing device.

Dimensions
Allow introduction of microwires inside various materials without affecting their properties; including implanting the MicroWire to human tissue.

Versatile
Sensor can be safely implanted in human tissue, vein, implant (invasive) or become part of diagnostic device (non-invasive).

No batteries or power wires inside the body
Contactless sensing improves the patient comfort and reduces risk of battery leak and short-circuit of electronics.

Flexible
Thanks to its flexibility Microsensor is able to adapt to movements of muscles and organs.

Safe with MRI and X-ray imaging
RVmagnetics MicroWire is the only metallic sensor that patients can safely and repeatedly take MRI and X-ray images.

Passive sensor
Sensor requires no power source (only sensing device is low-powered).

Low power consumption (Sensing system/device)
Sensing system/device is powered in Microampere (µA).

Simple measuring process
Sensing device can be connected to the mobile phone without additional electronics.

Resistant
MicroWires are resistant to chemically and mechanically challenging environment. They are also short-circuit protected.

Contactless sensing
Allows contactless sensing due to magnetic nature.

Magnetic bi-stability
Sensors are always in saturation. Heavy magnetic and heavy electric fields do not influence the measurement.

Reliable
When sensor brakes, two sensors and two measurements are obtained.

Multifunctional
Microwires can sense the temperature, stress, position, magnetic field, flow, electrical current etc.

Temperature range and accuracy
Sensor is able to withstand the temperatures from -273 to 600°C; within human temperature range 35-44°C measuring with accuracy of 0.01°C.

Real time data monitoring
Up to 10.000 x per second.

Data transfer
Data from the sensing device are sent via USB, Wi-Fi, Bluetooth, Z-wave, SigFox etc.

Non-destructive application
MicroWires provide real-time data about the current condition of material and therefore allow non-destructive testing on all monitored points - opposed to destructive testing that is conducted on material samples only.

Robust
Able to withstand challenging mechanical environment.

Lifespan
Lifespan of the sensor itself is longer than 1000+ yrs.

Glass-coating
Biocompatible and enhances protection when used in chemically and biologically aggressive environment.

Spark-less sensing
Use of RVmagnetics sensors does not produce sparks and therefore can be safely placed in ignition sensitive environments.

Highly Durable
MicroWire is able to withstand hard-wear environment.

RVmagnetics is dedicated environmentally aware solution provider, thanks to:

• replacing several sensors with one

  one RVmagnetics sensor is able to sense temperature/pres­sure and magnetic field at once. We are also able to measure aouthe physical quantities like a electric current, flow, orientation, elongation, vibration and much more.

• replacing several sensor interfaces with just one

  one pair coils (excitation and sensing coil) is able to take measurements from 15 MicroWire sensors

• sensing works on low power consumption (enabling energy savings on sensing)

  single measurements needs just few milliAmperes

• adding 100.000 sensors to any material or product ads 1 gram!

  therefore causes almost no additional COx emmistions

• our sensors contribute to client ’s manufacturing excellence

  and helps reducing environmental footprint

• environmentally neutral sensor