Symforest is an interactive installation/experience manipulated by human emotion.


My focus in this piece is on expanding body’s memory and skin consciousness. For example, unfamiliar sense in familiarity. Nighttime often makes familiar scenes in daytime very unfamiliar. In such situation, only thing you can rely on is your body perception to explore the new space. Using full senses, you have to explore and memorize the new environment. This act of engraving the memory of experience in mind becomes “experience and familiarity” to light up the unfamiliar, darkness.

How it works

As a participant walk through the small dark forest in the room with a lantern, audio events (field recorded sound, narratives etc..) are activated depends on where he/she is. Galvanic Skin Response sensor, which detects emotional arousal of its holder by measuring sweat level on the skin surface, is embedded in the lantern handle; therefore, the lantern light changes its brightness depending on the emotional condition and controls audio volume. Therefore, each person has different impression of the space.


Symforest activates/deactivates sounds by dark activated switches. This sensing field consists of 7 dark-activated light sensors and 7 laser pointers to operate sound switching system. Light sensors and laser pointers pair each other and are located across the room as shown in diagram picture. Sound switches are “off” by default. They are activated only when light sensors detect darkness, which is caused by the lasers being blocked by walking viewers. The detected switch statuses are processed through Arduino (Arduino Diecimila: USB) to trigger sounds. Each switch is assigned to a sound (either narrative or field recording sound).

Interface Prototype

I always want people to experience the work/environment more intuitively at least in my environment. GSR usually uses wearable finger-band-shaped sensors wrapping around your fingers to measure skin’s conductance between two fingers, but having people wear them gives very clinical and less welcoming experience. I came up with my first, first prototype for GSR device.


Basically there is 5 volts going to lower grip area (red wire). The upper area and lead splits to two wires. One wire goes to analog(0) and the other goes through a 100k (300k was suggested but lower registers worked out better on this.) resistor and then to ground. What’s read in analog(0) is the change in resistance of the voltage going through participants’ body.

Resistor Ladders as Analog Input

Since I need to read many switches and the number of my arduino’s pins are limited. First I looked at the resistor ladder, which allows me to read multiple switches on a single pin. This is very economical option. 🙂 You can tell the switch status by reading different values in resistance. So, in this case, higher the activated switch is, more resistors to go through, thus higher the resistance you are reading.<br>….but this can read only one switch at a time 🙁


Finally, this is the readjusted switch circuit that multiplied to make 7 switches.

Powering laser pointers

I’m using laser pointers to trigger light switches, but I need to power them from power supply, not batteries for easier maintenance for long-term exhibition (2 weeks). I got cheap laser pointers ($1.75 each), and they run with 3 button cells (total of 4.5v). 

First thing I did was to directly hook them up with 5v power supply, but it stopped working after 10 second I pressed the buttons.

….well, no surprise!!! Looks like they won’t work with more than 4.5v, otherwise I’m frying them up.

Learning Summary
  • Power the pointers using a variable voltage regulator, LM317
  • Don’t let the voltage go higher than 4.5!
  • Put a 100 ohm potentiometer on the negative line and turned the current down slightly, in order to keep the pointer from burning out. Also try some low value (10 ohms +) fixed resistors.
  • Category

    Interactive Installation
    Process Documentation

  • Tools & Media

    Arduino Diecimila
    Arduino Bluetooth
    GSR Sensors
    Conductive thread