The magic of printable magnets


Product from Polymagnet. .gif from

Product from Polymagnet. .gif from

This mysterious red thing was given to three engineers with the question: “Can you explain this?”

They took it in their hands, and pulled, turned and twisted the thing, only to be more confused.
When the two handles were far apart, they attracted each other, but when they were close they repelled. And when twisted to a certain position, they came together.

Magical. How is it possible? They asked, mindblown.
Actually, it is magnets. But in a completely new way.

The scene above is from this video (click, it’s a must-watch!), by smartereveryday, who visits the company behind this ‘toy’, Polymagnet.

They have developed a technology to print magnetic designs on the surface of magnets. This means that they can create multiple north and south poles on the same surface, and the higher density of poles – the tighter the ‘reach’ of the magnet gets.

The reach of the polymagnets can be tailored. Screenshot from the video by smartereveryday.

The reach of the polymagnets can be tailored. Screenshot from the video by smartereveryday.

Apart from being able to tailor the reach of the magnetic field, the focused force of the polymagnets mean that there are less interference and energy waste. And of course, since the magnetic patterns are printed to a very fine detail, where every maxel (magnetic pixel) represents one pole, the designs have no limits.

Printing maxels (magnetic pixels) allow infinite possibilities of magnetic patterns. Screenshot from the video by smartereveryday.

Printing maxels (magnetic pixels) allow infinite possibilities of magnetic patterns. Screenshot from the video by smartereveryday.

So, if we have a look at the mysterious red object again, the magnetic viewing film shows that the magnetic pattern is in the shape of the cog, which explains why it comes together when twisted to the right position.

The latch mechanism shown on magnetic viewing film. Screenshot from the video by smartereveryday.

The latch mechanism shown on magnetic viewing film.
Screenshot from the video by smartereveryday.

And with our new knowledge about the ‘reach’, we can imagine the magnetic pattern has been designed with a long reach attraction and short reach repulsion. And it’s all between two magnets.

This specific design, with its spring and latch mechanism, is thought be a good fit for a cabinet door closure. But really, when you can tailor the strength and geometry of the magnetic pattern, the possibilities for the Polymagnets are endless.

They call it ‘smart magnets’.
And it is hard to disagree.

It is clear that these are not only toys, that instead this innovation can revolutionise the use of magnets in product design.

Magnets in art (and design)

Ever since magnetism was discovered thousands of years ago, people have been fascinated by it. And of course we are, anyone who has played with magnets and felt the magnetism knows that it is a special force; an invisible, powerful and almost magical force.

Which makes it perfect for art, where the artists can explore freely and create and visualize concepts in ways that not only looks cool; it makes us think.

Below I have collected some examples of art based on magnetism.

Measuring Space #6 Variation 2, 2013 by Eske Rex Oak, maple, leash, magnets 22 × 7.5 cm

“Measuring Space #6 Variation 2″, 2013 by Eske Rex
Oak, maple, leash, magnets
22 × 7.5 cm

A popular theme is to play the magnetic force against gravity.

In the piece by Eske Rex above, the magnetic force cancels out the gravitational force, and we get what looks like zero gravity.
Bruce Gray’s “Suspension”, below, is based on a similar idea, however there is a sense of motion to this piece.

"Suspension", by Bruce Gray.

“Suspension”, by Bruce Gray.

Wooden Box with Horseshoe Magnet, 2006 by Caleb Charland.

Wooden Box with Horseshoe Magnet, 2006 by Caleb Charland.

The concept is taken to an extreme in Caleb Charlands sculpture above. The observer is a bit puzzled by how the heavy magnet can stay in that position, without anything physically keeping it in place, except the magnetism, which flow lines are symbolized by strings, but are more correctly visualized in “Magnetic Fields II” below.


"Magnetic Fields II", 2014 by Caleb Charland

“Magnetic Fields II”, 2014 by Caleb Charland

350 points towards infinity, 2009, by Tatiana Trouve Plumb, magnets

350 points towards infinity, 2009, by Tatiana Trouve
Plumb, magnets

The last one on the theme is the piece by Tatiana Trouve, above. Also here the objects seem to not be in equilibrium, which almost settles one in unrest.

Magnetism has also been used for moving artworks, like the video (click here or on the image) below by Kaplamino, who used marbles and magnets to make a Rube Goldberg machine.




Finally, two examples where magnetism has been used for interior design products. A levitating bonsai tree, and a ferrofluid clock (click on the images).

Air Bonsai by Japanese company Hoshinchu

Air Bonsai by Japanese company Hoshinchu

Ferrolic, by Zelf Koelman

Ferrolic, by Zelf Koelman

Magnet implants – to (re)gain a fifth sense

Did you know that the main reason for hearing problems and deafness is hair loss? And that magnets can be part of the rescue?

Following last week’s post on magnet implants, I will now show you an example where magnet implants are truly functional, and are already in use: cochlear implants, advanced hearing aids.

Cochlea is the fancy name for the inner ear. As you know sound waves enter the ear through the outer ear, goes through the ear canal and reaches middle ear where the eardrum, hammer, anvil and the stirrup starts vibrating in a chain. The vibrations reach the inner ear, the cochlea, where the mechanical energy is converted into electrical signals that nerv cells can transport to the brain so that we can make sense of the sounds.

So, I mentioned that hair loss can lead to hearing problems?

The cochlea is a spiralling tube that is filled with fluid and lined with sensory cells, aka ‘hair cells’, through the whole tube. The hair cells have varying sensitivity to sound frequencies; high pitch tones are absorbed in the base of the spirall, and base tones further in, in the apex. When the vibrations from a sound enters the cochlea, the liquid starts moving, and the surface of the hair cell moves correspondingly. These movements creates tension differences which produce electrical signals that are passed along the hearing nerve to the brain.

It’s all very nicely animated in this video by Med-El (from which the description above is taken):

Screen Shot 2015-06-10 at 11.12.41

Hearing problems can be due to defects and damages in either the outer, middle, or inner ear. Most are related to the inner ear, and the lack of, or damaged, hair cells in the cochlea!

Damaged hair cells can cause distorted hearing, tinnitus, and deafness. It is also the reason why humans get worse hearing when growing old, becausethe hair cells can get damaged by noise, drugs, infections etc, and they can’t regrow.

Under an electron microscope, it can look like this:


image source:

Luckily, there is help to be found: the cochlear implant. Unlike the ear, there are only two parts of it, the external and the internal. The external part consists of a microphone that picks up sound, and a speech processor that digitizes the sound into signals which are then transmitted into the (internal) cochlear implant by a transmitting coil. On the inside, in the actual implant, there is an internal processor placed behind the ear (fixed in a bone), that picks up the message and sends electrical energy to an array of up to 22 electrodes that has been inserted into the cochlea and replaced the hair cells in the job of stimulating the auditory nerve fibers in there.

CIdiagram_MAESTRO Cross Section_720

Image source:

The surgery takes a couple of hours and the patient can normally go home on the same day. After 1–4 weeks of healing, the implant is “activated” by connecting the external part to the internal device, via magnets on each sides! (shown more clear below)


Image source:

The initial results of the implant vary widely, and post-implantation therapy is required as well as time for the brain to adapt to hearing new sounds.

Hearing with the implant is not exactly like normal hearing; voices can sound static, robotic or cartoonish. You can try it out on this site.

Remember, 22 electrodes have been given the task to replace 16000 hair cells which is quite a challenge, so there are ideas to increase the number of electrodes. Most patients only get the implant on one ear, but studys suggest that it might help to get one on the second ear as well. This would give stereo hearing and help in sound localisation, and it might even make music appreciable.

The implant is only for people with severe hearing problems, or that are deaf. It is for adults who have been able to hear before, and learnt how to process sounds, or for children who have not passed the critical time where humans learn this, so preferably before the age of 2-3. (Kids who lack an auditory nerve can get auditory brainstem implant, which is similar but the signal goes straight to the brainstem instead of the cochlea.)

The implant is quite expensive so it is more frequent in richer countries. The cost for the implant should however be related to what is saved on special-education costs that are no longer needed. In 2000 it was stated that 1/10 children born deaf in the US had cochlear implants, and the number was expected to grow fast.

Hopefully it will, because:

Seeing the reaction of someone regaining their sense of hearing is truly something.
Or an infant that hear it’s parents’ voices for the first time.


Read more:


‘A sixth sence’ through magnet implants

Body-hackers (and scientists) use technology to evolve the human body.

Physical appearance has always been important for us humans, and through history there has been quite a variation of methods we’ve used to improve or change our appearance. Most common in our days is the use of clothes and cosmetics, but during the last few decades it has become increasingly popular with surgical methods to enhance lips, breasts, hairgrowth etc, or to get a tattoo or a piercing.

Now there are people, so called ‘body-hackers’, that seems to be taking this one step further, and not only change how they look, but instead change how they function.

 “How much can I push the human, how much can I consciously evolve the human body, to do more, to do it better, do it faster and stronger ”, Shawn Sarver says in the documentary “Biohackers: A journey into cyborg America” before he gets a Neodymium magnet impanted in his finger.  But why does he do it?


 Picture 1. Paper clip attracted to magnet implant in finger. Source:

After the operation, whenever he enters a magnetic field, the magnet starts reacting to that, and vibrates. The stronger the field, the more it vibrates, and because the magnet is surrounded by nerv cells in the finger, he can ‘feel’ the magnetism. This ‘sixth sense’ is called magnetoception – the ability to sense magnetic fields, just like sea turtless and birds!

It was first done in 2005, and since then several people have followed, and perfected the procedure through trials, errors and online discussions. But it is of course still not something I would recommend, mainly because you can’t have it done by a surgeon. Instead you have to consult a specialised body artist, and they are not allowed to use anesthesia, why it is a very painful procedure!


Picture 2. The operation. Source: “Biohackers: A journey into cyborg America”

To insert the magnet, you need to open up your finger with a scalpel, and then insert the magnet with a tweezer or a big syringe. With the magnet in position, you need to sew up. After the surgery it will take a few days for the scar tissue to build, and for nerv endings to settle. Then you will feel the sensation of the magnet touching your nerv cells, but it will take a while before your brain understands what it is.

The main risk is infections. As with all surgerys, there are risks with contamination from the air or any objects that are close, and could give infections. And with the use of scalpel, there is always a risk of cutting something wrong. The magnet is a potential risk as well, and has to be coated with a compound that is suitable for the environment inside the finger.


Picture 3. X-ray of the hand with the implant. Source:

It is suggested that the best position of the magnet is on the ring finger of your secondary hand, because if something goes very wrong, you want it to be on your least important finger. Also it shouldn’t be between the bone and the touch surface because if you have to grab something in an emergency situation, that could really hurt, and shatter the magnet.

How will this ‘sixth sense’ change your life?

The risk of demagnetising your credit card or disk drives are minimal, remember you can only lift very light objects, like the paperclip, with it, but I wouldn’t enter an MRI with the implant still in.

You will be able to sense magnetic fields – the finger will vibrate when close to an electric motor or a microwave oven. You will be able to pick up tiny metal objects, determine if a metal is ferrous. For electronics you could feel which wires are dead and live. And I bet some people do it just for the party trick. But not everyone.

Remember the guy from the video above, Shawn Sarver? He is part of Grindhouse Wetware who are developing a product called ‘Bottlenose’ that you put on the finger with the implant, and stimulates it with additional senses. For example, they are using an IR sensor that detects remote temperatures and emits an induced magnetic field – that the magnet will react on. The stronger vibration – the warmer it is. The video on this link shows how a person with blindfold successfully finds a person that is hiding in a room, using this device.

The same, and other similar, activities are actually also done in university environments. Professor Kevin Warwick (video link) of Reading University has studied various examples of sensory substitution. Using ultrasound instead of infrared light, you could feel how far away objects are from the finger, like a radar.

Professor Warwick sees potential applications in both the military and healthcare sector.


TEDx Warwick

The magnets of the green cars: Sensors

Ever wondered why your laptop turns into sleep when you close it?

It is because of magnetic sensors! There is a magnet on the screen-side, and a sensor on the keyboard-side. When they get close, the sensor feels it and turns a switch.

Picture showing how a sensor on the keyboard-side of the device can be used to detect a magnet on the screen-side, and use the output to switch the power on/off.

Picture showing how a sensor on the keyboard-side of the device can be used to detect a magnet on the screen-side, and use the output to switch the power on/off.  Source: Toshiba


Following last week´s post on the use of magnets in motors, this post will be about the magnetic sensors we find in cars.

Lets start at the beginning. There are numerous types of magnetic sensors, and they can be divided into three classes, depending on how they are used in relation to the ever-present magnetic field of the Earth.

There are the sensors for High sensitivity (that are highly sensitive to the magnetic field of the Earth) called MAD, which can detect ferromagnetic objects from long distances. These sensors are used to detect mines, ships and airplanes etc., and are based on the fact that the magnetic fields of ferromagnetic materials (its dipole moment) will distort the field lines of the ambient magnetic field, or create anomalies, why MAD is short for Magnetic Anomaly Detection. See picture below.

Picture showing how MAD (Magnetic Anomaly Detection) works. The dipole moment from ferromagnetic materials will distort the ambient magnet field lines.

Picture showing how MAD (Magnetic Anomaly Detection) works. The dipole moment from ferromagnetic materials will distort the ambient magnet field lines. Source: Lenz, 2006.

Then there are the sensors of Medium sensitivity that are working with (sensing) the Earths magnetic field, and they are known as compasses.
Finally, we have the sensors that are not very sensitive, and it is in this segment we find the two types of magnetic sensors that dominate in cars.

2 main types: The Hall sensor, and the AMR sensor.

The Hall sensor contains a conducting material through which a current is applied, and the voltage across the material is measured. When a magnetic field acts on the system, the voltage will change (the Hall Effect), and indicate the strength of the magnetic field.

AMR is short for Anisotropic Magneto Resistivity, which is the basis for this type of sensor. The main constituent is a Permalloy (80 % Nickel, 20 % Iron) thin film deposited onto a silicon wafer. The films properties are such that the resistivity can change 2-3 % in the presence of a magnetic field. As with the Hall sensor, the voltage (= resistance x current) is measured to indicate the strength of the magnetic field. 

Both these types of sensors are of simple design, cheap to manufacture. There are differences; for example that Hall sensor detects fields that are perpendicular to the current, while AMR senses parallel fields. The AMR has a wider detection area, and are faster, but Hall sensors are still cheaper, and can be smaller (down to a couple of millimetres) why they are more popular. With that said, they are still used for similar applications.

Now, lets focus on the cars again and how these sensors are used in them. We start with the wheel speed sensor.

Connected to the wheels of your car, there is a wheel speed sensor that measures the rotation speed of the pulse wheel (a wheel that is connected to the actual driving wheel, so it has the same speed). A sensor – often a Hall sensor with an incorporated magnet – is positioned so that the magnetic field from the magnet “covers” the cogged pulse wheel. Since the cogged pulse wheel is ferromagnetic, it will change the magnetic field depending on the cog is up or down, and thus also change the output voltage of the sensor. A microprocessor then keeps track of how many ups and downs there has been per time unit, and calculates the speed from that. See picture below.

Picture showing the graph for the output voltage from a Hall sensor next to the Pulse wheel.

Picture showing the graph for the output voltage from a Hall sensor next to the Pulse wheel. Source: Hella

Wheel speed sensors improve comfort and safety

Apart from telling you the speed of your car, the information from the speed sensors can be used to make driving more comfortable, for example with the use of cruise control. You set a speed you want to keep, and when the speed drops below, a signal is sent to the fuel pump to pump harder.

It is also used for safety applications. Heard of ABS? It is short for Anti-lock Braking System, and is a control system that modulates the break pressure in response to the detected wheel speed deceleration. So if you do an emergency break, the wheels won’t lock, instead it makes sure that the car decelerates in a controlled manner, so that the steer ability is not lost and the car won’t slide. (Read more here.)


Ever wondered how the fuel level is measured?

A Hall-type magnetic sensor is installed in the ceiling of the tank, and a floating magnet is put into the tank. The higher the level is, the closer the magnet is to the sensor and the higher the output will be. See picture below.

Picture showing how fuel level can be measured. By using a Hall sensor at the top, the distance to a floating magnet, and thus the level, can be measured.

Picture showing how fuel level can be measured. By using a Hall sensor at the top, the distance to a floating magnet, and thus the level, can be measured. Source: Nagarjuna College


Volvos aims to revolutionise road travel with magnetic sensors

The magnetic sensors can be used for a lot of things. In fact, Volvo thinks that they could
be used to guide tomorrow’s autonomous cars.

The idea is to put magnets into the roads, and then use magnetic sensors on the underside of the car to sense where it’s going and what is in the surroundings. This would improve both comfort and safety.

Video: TomoNews

I bet you wonder which kind of sensor they use?

With car speeds of 90 km/h, the sensors need a sampling rate of 400 readings per second.  And since the sampling rate of the Hall sensor is far from this, they have to use AMR sensors, which are much faster.

Volvo actually built a test road (in Hällered, Sweden) and tried the technology out, and if they can reduce the costs ($24,405 per kilometer highway), the future where we drive autonomous cars might not be that far away after all.