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12. Skin Electronics

Research

inspo

This week, I wanted to build upon my idea from soft robotics week. I also left Amsterdam this week to be in Dallas for a month, so I had limited time. I felt like I came to a nice stopping point with the project and have a few more steps to add to my documentation when I return in January.

I explored physical exercises that can be therapeutic for facial nerve injury. There are many outputs that can come from a device applied to skin: heat, pressure, vibration. This is what biofeedback aims to do. But, it also is important to visualize and then move the affected muscles. I decided on embedding LEDs in a wearable device that can provide a visual cue for exercising the muscles I personally need to work on as I continue recovering from temporary paralysis on that side of my face.

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References & Inspiration

process

I reworked the original design I made during soft robotics week in order to cast a thin sheet of silicone. I then 3D printed it with the generic PLA settings on a Prusa CoreOne printer.

Having the physical object allowed me to determine the size, shape, and layout of my circuit. After building it out, I decided that embedding the circuit inside the silicone would make it more secure and wearable, but there is more on that further down this page.

Tools

Process and workflow

After making the silicone pieces, I worked on Arduino. My idea was simple, I wanted to keep it approachable as a beginner. I am very interested in Arduino, but I feel like taking small steps works best for me to actually learn the language, vocabulary, and functions.

arduino

This was also my first time using a breadboard to visualize an Arduino Sketch before applying it to my design. This was SO helpful in understanding the flow of the circuit.

Alternate blinking on 2 LEDs with Arduino UNO | Maddie Olsen | Fabricademy 2025 by Maddie Olsen

I also floated the idea of adding a switch or touch sensor. I tested a push-button switch with the breadboard and also tweaked the code to be readable by by ESP32/fabriXIAO microcontroller.

Button and alternate blinking on 2 LEDs with fabriXIAO ESP32S3 | Maddie Olsen | Fabricademy 2025 by Maddie Olsen

Code Example

Just Alternating Blinking

int LED1 = D6;
int LED2 = D7;
  //for fabriXIAO name pins D6, D7; for arduino uno name pins 6, 7

void setup() {
   // put your setup code here, to run once:
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
for(int i=0; i<10; i++){
  digitalWrite(LED1, HIGH);
  delay(500);
  digitalWrite(LED1, LOW);
  delay(500);
}
for(int i=0; i<10; i++){
  digitalWrite(LED2, HIGH);
  delay(500);
  digitalWrite(LED2, LOW);
  delay(500);
}
}

Add a Push Button/Switch

int LED1 = D7;  // LED pins
int LED2 = D6;
int BUTTON = D5; // Button connected to pin 5
// remove "D" if using arduino uno


void setup() {
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP); // Internal pull-up resistor
}


void loop() {
  // Check if button is pressed
  if (digitalRead(BUTTON) == LOW) { // Button pressed
    for(int i=0; i<10; i++){
      digitalWrite(LED1, HIGH);
      delay(500);
      digitalWrite(LED1, LOW);
      delay(500);
    }
    for(int i=0; i<10; i++){
      digitalWrite(LED2, HIGH);
      delay(500);
      digitalWrite(LED2, LOW);
      delay(500);
    }
  }
}

I didn't add a touch sensor when I tried this week. However, I think I could take a look at how I did this when I made a soft speaker during wearables week, because that sketch combined the tone function with a touch sensor.

Soldering the circuit

leds working

I chose LEDs from an adhesive strip for their flat profile and adhesive backing. They had solderable pads on the surface that were easier to work with than the tiny SMDs we had. Using my arduino sketch, I tested that the leds were working before getting started with soldering.

In the past when I have soldered for jewelry-making I had used flux, but so far in this course we had not needed it. I tested the solder on a scrap of the tape without an LED and couldn't get the solder to flow onto the copper trace. It just stayed balled on the tip of the soldering iron, while the heat melted the plastic coating on the tape. Adding a drop of flux instantly solved this problem.

soldering

Results

Schematic

Once soldered, I connected the power/pin and ground wires as shown in the schematic and it worked! I then found out the adhesive of the LEDs couldn't or wouldn't stick to the silicone piece. I tested the appeareance of the final product by adhereing the LEDs to my skin and laying the silicone over the top (then I washed my face as soon as I got home). I enjoy how the light diffuses through the silicone.

progress

At this point I have visualized the final result, but need to embed it in silicone. I did not have time to do this and document it beofre leaving de Waag on Friday evening. I feel it should be monitored in case the wires pop up out of the silicone before it cured, so I want to finish this part when I come back to Amsterdam in January.

Video

Fabrication files

  1. [Rhino] ↩

  2. [Arduino alternate blinking between 2 LEDs] ↩