IoT and Capacitive Touch through Quartz

Hi all,

I’m looking to make a gift for my long-distance SO in the form of two small crystals on pedestals - one for me and one for her. They can be powered from the wall and sit on our respective places of work. When one of us touches a crystal, the other will glow blue - a way to send a quick and subtle “hello” while we work. If both are touched they will both glow red - a nice way to feel connected across a country.

There are two main issues I’m looking to solve. The first question is which IoT device should run the thing. I’m not new to electronics projects but I am new to the IoT world. My needs are pretty basic: Any amount of space and processing power should be plenty, and I’ll need three pins for an RGB LED and maybe two for my touch input. I’m between the Electric Imp and the Sparkfun ESP8266 Thing. The Thing is cheaper and should suffice, but the Imp (~2x the cost) has some cool features like remote code uploads. If anyone has feedback in this area or another suggestion I’m all ears.

The larger issue is detecting touch. Ideally I’d use capacitive touch sensing since it’s cheap and easy, but I’m not sure if the properties of quartz or glass would allow the touch to be detected. I haven’t been able to find reliable information about the resistivity of natural quartz stone, and wouldn’t be sure how to interpret it if I did.

Using a metal touchpoint could work, but I’d sacrifice the niceness of having the actual touched object itself glow. I don’t like the idea of a button or anything moving or clicking - I’m shooting for a sleek and subtle experience. If anyone has feedback on the feasibility of detecting touch through a quartz stone or something like it, I’d love to hear it.

Feedback in general about product suggestions or design choices are also welcome.



I'm all ears.

Better than being all thumbs.

I think that you are going to find this project more challenging than you think. Each end will need to be both a client and a server. The client part tells the other server that it has been touched. The server part changes the color of the LED based on the input and the state of the touch sensor on its end.

Internet propagation times may make the device feel slow, rather defeating the purpose of the device.

Nothing beats personal testing.

I was hoping to sidestep this issues with some IoT service like Sparkfun's Phant or Thingspeak for the Sparkfun board. It's looking like these free services limit the number of updates to around once per ~15 seconds though, so that's a bit too slow.

The Imp claims that it runs "from the cloud". Does this mean I can have an application constantly running on Imp's servers, which both of the Imps communicate with? This seems like the simplest solution provided I'm understanding the framework correctly.

Essentially you are building a touch screen interface to an IRC server. For development, perhaps you could find a little used channel and repurpose it for private communications. If the concept works then look for a paid service.

Capacitive Sensing through 5mm of glass/quartz should work.

For a thicker piece of quartz you will probably need to use a load cell. Capacitive sensing would be preferred as it would be able to discriminate on the basis of dielectric constant.