Digital Dining With Charged Chopsticks

You step out of the audience onto a stage, and a hypnotist hands you a potato chip. The chip is salty and crunchy and you are convinced the chip is genuine. Now, replace the ordinary potato chip with a low-sodium version and replace the hypnotist with an Arduino. [Nimesha Ranasinghe] at the University of Maine’s Multisensory Interactive Media Lab wants to trick people into eating food with less salt by telling our tongues that we taste more salt than the recipe calls for with the help of electrical pulses controlled by everyone’s (least) favorite microcontroller.

Eating Cheetos with chopsticks is a famous lifehack but eating unsalted popcorn could join the list if these chopsticks take hold and people want to reduce their blood pressure. Salt is a flavor enhancer, so in a way, this approach can supplement any savory dish.

Smelling is another popular machine hack in the kitchen, and naturally, touch is popular beyond phone screens. You have probably heard some good audio hacks here, and we are always seeing fascination stuff with video.

Etching Your Own Metal

It’s been said that with enough soap, one could blow up just about anything. A more modern interpretation of this thought is that with enough knowledge of chemistry, anything is possible. To that end, [Peter] has certainly been doing a good job of putting his knowledge to good use. He recently worked out a relatively inexpensive and easy way to etch metals using some chemistry skill and a little bit of electricity.

After preparing a set of stencils and cleaning the metal work surface, [Peter] sets his work piece in a salt solution. A metal bar is inserted in the other end of the bath, and both it and the work piece are connected to electrodes. The flow of electricity removes some metal from the exposed work surfaces, producing whatever patterns [Peter] wants.

One interesting thing that [Peter] found is that the voltage must stay under 6 volts. This is probably part of the reason it’s relatively easy to etch with even a wall wort. Above that, the iron work piece produces a different ion which can clog the work surface and create undesirable effects. Additionally, since his first experiments with this process he has upgraded the salt bath with magnetic stirrers. He also gets the best results in a very cold environment.

There are many other uses for etching metals, too. Creating your own printed circuit boards comes to mind, but there are plenty of other uses as well. What will you do with this technique?

Water Purification Uses Home-built Electrolysis Rig

If you plan ahead a little bit you could have your own system of water purification to use in emergencies. Everyone needs clean drinking water and this gadget will let your produce your own purification drops quite easily.

The solution contains chlorine, which is created through electrolysis. The PVC cap seen near the bottom of the image has two electrodes sticking out of it. These are titanium plated mesh plates separated by a rubber ring. The cap has a small hole in it to keep the flow rate low and the fitting at the top acts as a funnel. When you pour in a salt water mixture it passes through the energized plates and a chemical reaction splits the sodium from the chlorine.

A twelve volt power source is necessary for this to work. But since the electrolytic process takes just a minute or two you could easily source the power from batteries charged with solar cells. Check out a full build walk through and demonstration video after the break.

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Etching PCBs With Vinegar

When we hear about etching PCBs at home we assume that either Ferric Chloride or Cupric Chloride were used to eat away unmasked copper from the boards. But [Quinn Dunki] just wrote up her PCB etching guide and she doesn’t use either of those. Instead, she combines vinegar, hydrogen peroxide, and salt. It’s easier to find vinegar than muriatic acid (Cupric Chloride is made using this, peroxide, and adding the copper) so this is something to keep in mind if you’re in a pinch (or a Macgyver situation).

The rest of the process is what we’re used to. She’s using photoresistant boards which can be masked with a sheet of transparency instead of using the toner-transfer method. Once they take a bath in the developer solution she puts them in a shallow dish of vinegar and hydrogen peroxide along with a teaspoon of salt. She wipes the surface with a foam brush every minute or so, and inspects them every ten minutes to see if they’re done.

She does discuss disposal. Seems that she throws the solution in the garbage after each use. The liquid will contain copper salts which are bad for wildlife. We’ve heard that you should neutralize the acid and make a block of concrete using the liquid, then throw it in the garbage. Does anyone have a well-researched, ethical, and environmentally friendly way of getting rid of this stuff?