DIY Capacitive Stylus


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Introduction: DIY Capacitive Stylus

My name is Jason Poel Smith. In my free time, I am an Inventor, Maker, Hacker, Tinker, and all arou…



Most smart phones and tablets have capacitive touch screens. This is an impressive bit of technology that lets you interact directly with the screen using only your finger. But there is one problem with this kind of interface, messy finger foods. Nobody wants streaks of food all over their screen. One way to solve this problem is to use capacitive stylus. But you don't need to spend a lot of money on a commercial stylus when you can make one for free out of everyday items. In this instructable, I am going to share with you a few of my favorite designs for a DIY capacitive stylus.

Step 1: Background Information

There are several different kinds of capacitive sensing. But in general, they all work by using an array of sensors to monitor the electrostatic field around the screen. When your finger touches the screen, it changes the electrical capacitance of that portion of the screen. This is detected as a change in voltage at various locations. The microprocessor captures, filters, and analyzes the data. Then it calculates the coordinates of where the touch occurred. You can read more about capacitive sensing here: http://en.wikipedia.org/wiki/Capacitive_sensing

When a stylus is used, the same principles apply. The only difference is that the stylus is acting as a conductor to transmit electrical charge between your hand and the phone. In order to function properly, a capacitive stylus must meet several criteria.

1. A conductive surface: It must be able conduct an electrical charge between your hand and the screen. If the material is too resistive or if the distance between your hand and the screen is too great, the signal reaching the screen may be too weak to be detected.

2. At least 1/4 inch wide: When filtering data, the processor ignores areas that are significantly smaller than a human finger tip. This helps avoid unintentional activation. Having a stylus that is about 1/4 inch wide will ensure that there is enough surface area to be detected.

3. A relatively flat end: Having a flat tip ensures that the whole face can get close enough to the screen to be detected.

4. A smooth surface: This will ensure that you don't scratch up your screen.

Following these criteria, you can find a wide variety of common items that can be used to activate a capacitive touch screen. Here are five of my favorite designs for a DIY capacitive stylus.

Step 2: Metal Pen Stylus

The back end of many metal pens may be used as a stylus without any modification. The more metal there is in the pen, the more sensitive and more reliable it will be. When selecting a pen be careful to avoid shiny plastic that may look like metal. This is probably the most convenient stylus because it can function as both a pen and a stylus. 

Step 3: Battery Stylus

The negative end of a battery (such as a AA, AAA, or AAAA) can also act as a stylus without any modification. However, if you would like to make it more sensitive, you can remove any insulating wrapping. A battery makes a great impromptu stylus. With the prevalence of hand help electronics we are rarely far from a battery of some kind.

Step 4: Sponge Stylus

Probably the most interesting material that can be used to activate a capacitive touch screen is a sponge. It's cheap, effective and actually cleans your screen as you use it. But a sponge is a bit too flexible to make an effective stylus as it is. To fix this, the easiest thing to do is to insert the sponge into a metal pen barrel or other metal tube. This gives it shape and makes it a lot easier to work with. 

Cut off a strip of sponge that is about 1/2 inch wide and about 3 inches long. Pinch the end of the sponge and twist it into the barrel until you have 1/2-1 inch sticking out the end. Make sure that the sponge is deep enough that it makes good contact with the metal housing. Then trim the tip of the sponge with a pair of scissors and round it off. This helps make the stylus more accurate.

The only problem with using a sponge as a stylus is that it will not work if it is completely dried out. The water in the sponge helps conduct the charge. So periodically you need to rewet the sponge. It doesn't need to be soaked, just moist enough that the sponge is flexible.

Step 5: Office Supply Stylus

While most office supplies are either too small (like paper clips) or too large (such as staplers and hole punches) to be conveniently used as a stylus, there are quite a few that work quite well. Some examples of metal office supplies that will work as a stylus are scissors with metal handles, a name tag clip, binder clamps, or an unbroken bunch of staples. The best way to figure out what will work is to just open up your office supply drawer and start trying different things out.

Step 6: Foil Stylus

Pretty much anything wrapped in foil can work as a stylus. A pencil or pen wrapped in foil is probably the simplest example. Just tear off a piece of foil that is about 3-4 inches long. Then roll it onto the pencil leaving about an inch of foil sticking out past the eraser. When it is rolled up, fold this extra bit of foil over the end. Then fold up any sharp ends. To finish smoothing the end, you may want to press it against a table on all sides to ensure that the end is flat and free of any sharp edges. The creased foil should hold itself in place, but if you use tape to secure the foil, make sure that there is enough exposed foil to make a good contact with your hand. If the stylus is not very responsive, you may wish to adjust the shape of the tip by either pressing it into a different shape or rerolling it.

Step 7: Other Materials

There are a lot of other materials that can be used to activate a capacitive touch screen. Here are just a few.

The head of a bolt or screw
Nails with a wide head
Silverware
The inside of a zipper
A capacitor
A metal thumbtack
A rolled up green leaf
Wet paper towel/napkin
A stack of quarters
A freshly cut twig or stem
A pocket knife or multi-tool
Large Keys
The back end of a drill bit
Anti-static film
Anything porous that is wet
Anything that is made of metal that has the right shape

This is just a short list of some materials that will work. Feel free to try out whatever you have laying around. If you think of a particularly interesting material that works, leave a comment and share.

7 People Made This Project!

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52 Comments

0
orangeade.
orangeade.

6 years ago

i used a bobby pin, the coated end works too and doesn't scratch the screen.

0
dax321
dax321

Reply 2 months ago

What's bobby pin?

0
sanlpetty
sanlpetty

5 months ago on Step 1

Where I live, stylus's are not easy to find, nor cheap. I once bought a package of 12 off WISH, but eventually they wore out. After reading about other peoples ideas for stylus's, all great ideas, I decided to try using saran wrap, wapping the rubber tip with it so that just one thin layer of saran wrap covered the black rubbe tip and the excess wrapped around the shaft. Surprisingly, it works just like a brand new stylus. The only down fall is that it looks like crap AND after a while the thin layer of saran wrap tears. If you use it for just texting, the saran wrap will last longer, while, if you use it to scroll alot, it will tear.
I am an older lady with fat fingers, trying to type a text or play a game on my phone with my fingers is frustrating. Also just as frustrating is using a worn out stylus. A quick fix is to use saran wrap.

0
hhhhhhhhhhhhm
hhhhhhhhhhhhm

Question 1 year ago

i used a battery and it worked great, but batteries aren't very long so i stuck it on a pencil--it stopped working when i had it on there, but it worked fine when i took it off. what can i put it on to make sure it keeps working?

0
Flip Recrute
Flip Recrute

Answer 8 months ago

Try using foil. Wood, plastic, etc don’t conduct electricity. Metal can conduct electricity and so does foil.

0
Darksonic232
Darksonic232

Question 1 year ago on Step 6

But what if it sratches the screen?

0
aahaan.jain
aahaan.jain

Answer 1 year ago

to not get scratches on the screen i prefer the sponge one

0
lacamera
lacamera

2 years ago

Hi,. If the sensitive part, the screen sensor, is removed because it could no more functioning, what can I do? Can any of the methods listed work? If they could not, what do you think can work for this situation.
mkam0001@gmail.com

0
EMIL¥
EMIL¥

Reply 1 year ago

Hi, I am a phone technician here. What controls touch is on the actual motherboard, you can’t get it removed, but it can stop touch when There is bending or breakage with tiny pins located on the motherboard. Also, if you see a weird gray line at the top of your screen that comes and goes, it’s a software issue.
Motherboards can be repaired but you’ll have to find a shop willing to do it, it’s a difficult and fragile repair and very expensive.
I bought a lightning to female USB adapter, I was then able to plug in a usb on a standard keyboard.
I also later used a Bluetooth keyboard attached to an iPad mini case, by using the first keyboard to turn on and pair Bluetooth.
This is good to retrieve a back up of what was on that phone soooooo you won’t lose all your information

0
Nandu2u2
Nandu2u2

Reply 2 years ago

You can find a way to plug a mouse in and use that if it's android.

0
GuineaPigKitKat
GuineaPigKitKat

5 years ago

I tried the tin foil one, but it never let me touch with it on my iPad or iPhone... What do I do?

0
hack_anything∞
hack_anything∞

Reply 1 year ago

You should touch the foil to make it work

0
LadyWalker43
LadyWalker43

Question 3 years ago on Step 7

Will any of these stylus pens work on Apple iPhones??

0
hack_anything∞
hack_anything∞

Answer 1 year ago

Yes’m it will as it will not recognise it as Apple Pencil but as your finger

0
rraghavendran52
rraghavendran52

2 years ago on Step 2

Wonderful write up. Thanks. But using knife or sharp objects is not a good idea since they will damage the surface or our hands.

0
BrijeshMV
BrijeshMV

Question 2 years ago on Step 7

I tried using an aluminum hanger ~0,6-~0.7mm wide with tip shaped like pencil and ~10cm long, it isn’t working ? But if I use same piece horizontally, it works, why? Please help me with making it work vertically like pencil

0
RealX
RealX

Question 3 years ago on Step 3

Is using the battery dangerous?