E-Textile; Wearable I

OBJECTIVE
This class focused on exploring how we can produce soft circuits and sensors, to embed them into garments and wearables, using soft circuits and soft actuators.

CONDUCTIVE FABRIC

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BEND SENSOR
The objective of the first test was to build a sensor using the conductive fabric.
In my case, I build the Bend sensor using the following materials:
Materials: Neoprene
Conductive fabric: Pure copper
Conductive thread: Silk 6.4 Ohm
Resistance: Velostat

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  • Cut two swatches of Copper fabric and match it with the two neoprene pieces. Is possible to saw it or glue it. 
  • To run the electricity between the two copper pieces, I used a silver conductive thread.  Stich the thread on both neoprene piece, being careful to don’t go through the fabric, in this case, the neoprene thickness might be helpful.
  •  Close the sensor with the second piece of neoprene, putting the middle a Velostat. Is important that the wires don’t touch each other.
  • Now is time to Measure the voltage range. With a multimeter check the voltage in two states: when the sensor is stretched and when it is relaxed. If the voltage range is short we need to add a resistor.
  • In this case, I use the Velostat as a resistor 
    //Voltage range: 0.6 to 0.3 ohm ( from flat to bend) range with one Velostat.
  • In order to have  big range, I add one more layer of Velostat
    //Voltage range: 2.3 to 1 k/ohm (from flat to bend) with two Velostat

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  • The voltage range can be found dividing the max voltage with the min voltage.
  • According to the range choose the correct Resistance.  It will be used for the circuit.

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  •  POTENTIOMETER
    Moreover, is possible to measure the resistance using a potentiometer.
    91371-Adafruit-Breadboard-Trim-Potentiometer-10K-Pic01-1200x630w
    Open the Sketch in Arduino to read the potentiometer and set up the Arduino tab.
    Arduino –> File –>EXAMPLE –> 0.1 BASICS –> READ ANALOG VOLTAGE
    //find the biggest range
    //take off the Potentiometer and measure with the Multimeter the Ohm (in my case
    7.7  k/ohm)
  • Pick the correct Resistance.

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  • CIRCUIT – Stretch and Pressure
    • Once we know the resistant is possible to build the circuit. For this assignment, I followed the PDF  explained in the Class.
    • Sketch_Arduino_bb.png
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ARDUINO SKETCH
BLINK – THREE STATUS –

int sensorPin = 12; // select the input pin for the potentiometer
int threshold = 450; // threshold for turning the lamp on
const int ledPin = 13; // select the pin for the LED
int threshold1 = 370;
int threshold2 = 340;

int sensorValue = 0; // variable to store the value coming from the sensor
void setup() {
Serial.begin(9600);
// declare the ledPin as an OUTPUT:
pinMode(ledPin, OUTPUT);
}
void loop() {

// read the value from the sensor:
sensorValue = analogRead(sensorPin);
Serial.println(sensorValue);
delay(100);
// if it’s lower than the threshold
if(sensorValue < threshold)
{
digitalWrite(ledPin, LOW);
}
if (sensorValue >threshold || sensorValue < threshold1 ) {
// turn the LED on
digitalWrite(ledPin, HIGH);
delay(100);
digitalWrite(ledPin, LOW);
delay(100);
}
if (sensorValue > threshold || sensorValue < threshold2 ) {
// turn the LED off
digitalWrite(ledPin, HIGH);
delay(1000);

}

}


Exercise 02

Objective
Create a Soft circuit with an ATTiny

The soft circuit is becoming an interesting challenge year by year. In order to wear it all the wires, board and batteries need be placed in the comfort zone on the body but more important They can be replaced with smaller solutions.
For this assignment to create a soft circuit I will use an ATTiny. The ATTiny will be programmed with the Arduino sketch by the Tiny AVR Programmer.

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Install ATTiny

Open and Configure Arduino

  • Open Arduino and the sketch to program on the ATTiny.
  • Setup: Tool–> ATtiny / Processor –>ATtiny85 / Clock –>8MHz
  • Place the Programmer on the USB port and ATTiny on it.
  • Usually, the ATtiny85 has a dot next to Reset, this should be placed up towards the notch.
  • The atTINY present different pin numbers. Change the pin numbers on your code to run the function correctly  ( example from 13 to 0, from A0 to A1 )

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Potential error from the ‘Serial Port’ :  If the serial port make an error, remove it adding the  “//”.

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  • If all this step run correctly the Programmer will blink.

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  • Now the ATTiny has been a programmer. Make a test. Replace the wires from the Arduino board to the Programmer board.
  • Take off the ATtiny and start to build the circuit

link
https://learn.sparkfun.com/tutorials/tiny-avr-programmer-hookup-guide

 

BUILD THE SOFT CIRCUIT ON A GLOVE
In order to have a great value of stretch, I decided to place the sensor on top of the hand, next to the elbow.
Using a black neoprene fabric,  I build a glove and attached the stretch sensor on a fabric,  with metal bottom clips.
The atTINY, battery, and LED had been positioned next to the sensor in order to avoid the movement impedance.

 

IMG_8427.JPGOnce you placed the sensors is time to attach the atTINY and make the circuit,.
It is important to plane in advance the circuit connection in order to avoid the overlap of wires. If it is not possible to avoid the overlapping, protect the wire with a piece of fabric or other not conductive materials.

IMG_8564I used the copper wire as a conductive thread. The copper wire presents a protective film, therefore the ends parts have to be sand.

 

 

Stich the thread in the fabric manually and connect the power up the circuit with a button battery.IMG_8441

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