PED

Molds for the soldered board

After I tested the board as a wireless stand alone I decided that an enclosure was in order.

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This meant joining the knowledge of Prototyping Electronic Devices and Digital Fabrication classes in making the board and then designing the enclosure.

The design process started off with the following models:

These I consulted with Danny Rozin who suggested that I tried a dip casting (how rubber gloves are made), for this I created the following models

These dip molds were made at La Guardia studio. Since the date of delivery was going to take a while I decided to start working in another mold.

With the help of Chester Dols I created these models which will make up the spheric enclosure I´ve been dreaming of for so long.

The molds are comprised of 4 parts to do the casting and one part to hold the circuit.

 

This is the central part that will keep the casted mold hollow.

This is the bottom piece which has standing legs that will helo the casting

This top mold was divided in to so that placing the interior hollow mold would be possible.

All parts of the mold had long tabs made to allow for clamping. And the bulb mold had resporatory and casting holes which proved actually too narrow to use, it was actually this part what proved more need of adjusment but lets not jump ahead in the process.

The base and bulb molds were made in the Ultimaker 3 with a 6mm nozzel and PLA filament. It took for the machine an average of 25 hours to create each part. The two parts that comprise the top mold were made in a Fortus 450mc at Tandon´s makespace. The average cost of the outsourced jobs (drip molds and top mold) was of $20 USD due to the subsidy provided both by Tisch and Tandon.

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For the material I used Ecoflex 00-50 sylicone bought in the Complete Sculpture.

The casting process for the dripping molds was not successfull as the layer poured was too thin, so if I am to try this process again I would need a hardener for the ecoflex so that it cures faster and I can drip mor layers on top.

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The casting for the sphere mold, as I mentioned before was a little hard due to the pouring hole being too smal, it took some work to

It took 24 hours for the material to cure completly and the realese was extremly easy. Once it was done I installed the conict enclosure with the pressure sensor attached to a baterry holder inside the sphere I had to hold it with electrical tape to make sure it didn´t move but in general terms it was tightly sealed and the pressure sensing worked perfectly.

To further develop this prototype the bulb mold will be need to be improved so that casting is easier, the circuit enclosure holds to the sphere in a better way and I also need to create a lid to seal the enclosure part.

First Try: The hand soildered board

My two main goals with this part of the process were 

  1. Making the button a stand alone object
  2. Being able to release the model so other can use the basic structure of it, specially into the Sensor Library

With this in mind I started this project by transferring the code into an ATTINY85 and selecting the output to be a LED.

To install the code into the ATTINY85 I used an Arduino Uno as the loader. The process of doing this is pretty straight forward, both with regards to the code and the circuit setup. Since this code is very simple it doesn't need much tryout but if it needed to be revised (which I did only because I worked with a flawed ATTINY for about an hour) its better to have two boards, one that will test the sketch and another one that will load the code into the ATTINY.

Once the ATTINY85 was ready I set it up on a Breadboard for tryout with two 3V batteries.

At this point I realized there were two main components I needed to pay attention to in this prototype: the battery package and a switch.

As the enclosure I designed a holder to be laser cut and placed with standoffs above the board. This design includes a switch and the breadboard design considers a battery package for two 3V cell batteries. Due to time constrains and the battery packages I tried being horribly faulty I ended up creating my own "package" for the batteries, so this is something that still needs to be figured out so that it is included in the BOM.

Part of the idea of this board was that it could be placed into a ballon, closed in there and then just squish the ballon to get the signal. But this was not happening, because the sensor checks for pressure diference and by being withing the fluid it cannot register a change in the pressure since it is only displacing withing its atmosphere

So to hold the "guts" of the button I laser cutted a paper dodecahedron. This is not the best solution as the switch gets trapped inside of it. So if the button will be used in this application the board and the enclosure need to be design with the light diffuser.

Moving forward with this project this is the checklist:

  • Imagine other applications for this prototype other than a very weird flashlight
  • Create a board in which the output of the sensor can be changed
  • Also the communication of the sensor can be augmented, through giving the board a way of having a wifi/bluetooth integration, as well as communicating with another microcontroller or having a Serial communication port.
  • Have a 3D library of the components so new enclosures can be designed for different applications
  • Solving how power should be provided for the different communication solutions (wifi, serial, bluetooth)

In order to replicate this prototype the BOM would be:

  • Enema Bulb
  • MPX5010 case 867B-04
  • ATTINY85
  • 220 resistor
  • White LED
  • 2 3V cell batteries
  • Acrylic (or other material for enclosure) and standoffs

The schematics and code live here:

https://github.com/RSofiaC/pressureControl/tree/master/ATTINY85

Let's do this once more

For my "Do it once, do it again" project I want to dive deeper into a project I started working last semester: My squishy buttons

This project started from the idea of using the tangibility of a squeeze to activate a reaction. And what started as a LED in a balloon:

And for a Unity game inside a escape room experience.

 

All of these have been iterations on the same kind of sensor attached to the micro-controller in the same way: As an analog read getting a map of values that is then printed into the output.

This time around I would like to:

  • Explore wider capabilities of the sensor  (I'm just using three out of its six pins)
  • "De-attach" the sensor from the micro-controller
  • If possible place the sensor within the squish device.

I know there are similar products to this idea in the market, but what I'm trying to do is a pressure sensitive button not a ball that lights up.