Home Phones Galaxy Note How does the S-Pen Work? An MRI Scanner in your pocket!

How does the S-Pen Work? An MRI Scanner in your pocket!


As mobile technology progresses there is more scope for it to be adapted into the medical market, but have you ever thought that technology that was originally designed for the medical market might have made its way into your pocket? Introducing, the Samsung Galaxy Note. This handy ‘phablet’ comes with something known as the S-Pen which utilises a technology which has been designated EMR (electro-magnetic resonance).

Samsung Galaxy Note - Samsung Geeks

Also introducing the MRI (magnetic resonance imaging) scanner…

Can you tell where I’m heading with this yet? Let me break this down….

The MRI Machine

In most hospitals now there is a hulking great machine that uses a giant magnetic field (usually in the order of 15,000 times the strength of the Earth’s magnetic field) to align all the protons in the human body.

MRI Scanner - Samsung Geeks

After all of the protons are aligned, a radio signal is ‘bounced’ off these protons. The returning signal is received by a coil in the MRI scanner, other coils in the x,y and z axis aid the scanner in receiving location data of where the bits (of you!) are that the signal has bounced off. Then a computer pieces all this together and there you go, you have a highly detailed picture of the human body.

Mind blown yet? mine is…

Which sort of in a round about way brings me back to the Galaxy Note and particularly the S-Pen…

The S-Pen

Samsung Galaxy Note S-Pen - Samsung Geeks

Underneath that gorgeous screen there are two main boards; the sensor and the control board. The sensor board has coils arranged in the x and y axis (sound familiar?) and the control board uses alternating current to switch select coils in the sensor board on and off rapidly, this excites the little coils and they generate a magnetic field.

Each time the S-pen passes through these magnetic fields it picks up and stores energy in its resonant circuit. This energy is then used to return a magnetic signal back to the control board (number 3 in the Galaxy Note teardown picture from Samsung Tomorrow) in the Galaxy Note. Using this method, the S-pen can transmit a whole host of information such as angle, pressure and co-ordinates.

Now I hear you asking “why is that so much better than a usual stylus?!” or you may be saying “urgh, using a stylus is so 90’s!”

Why is the S-Pen better than a usual stylus?

Well lets head back to the fact that with the S-pen you can have up to 256 levels of pressure and it’s accurate to 0.5mm which is all down to the snazzy technology inside it., the S-pen also doesn’t need to be in contact with the screen for the Galaxy Note to register its position (it can be free to hover a few mm above the screen). Other styluses such as capacitive are just that….capacitive, this means there will be some kind of conductive material at the tip of the stylus.

Galaxy Note S Pen - Samsung Geeks

A capacitive screen works by detecting changes in capacitance of the screen, these slight changes are caused by distortion in the screens electrostatic field and in turn these distortions are caused by touching it with your finger (as we humans are electrically conductive!). Basically a capacitive stylus just mimics this effect, but with a smaller ‘point’ than your finger. Another type of screen that can use a stylus is the resistive touchscreen, now this doesn’t require a special capacitive stylus, any pointy thing will do!

htc touch diamond stylus - Samsung Geeks

A resistive touch screen is composed of two layers with an air gap or microdots between, on each layer there are horizontal and vertical lines, when these lines are pushed together they register the coordinates of the touch. In its own nature resistive technology isn’t very accurate and often you need to push that little bit harder to register a touch in the first place.

As you can see technology is a wonderful thing, and even the most largest sophisticated technology may be sitting in your pocket already!

If you’re interested in the technology in the Galaxy Note’s S-Pen and want more detail, check out Wacom’s explanation of the technology and Samsung Tomorrow’s Galaxy Note teardown.

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