Ensayos

Sound-Responsive Magnetic Fluid Display
Sachiko Kodama, Minako Takeno Dept. of Human Communications The University of Electro-Communications 1-5-1, Chofugaoka, Chofu-shi, Tokyo, JAPAN kodama@hc.uec.ac.jp
Abstract: A new magnetic fluid device is developed in which the magnetic fluid is manipulated in sync with sound. The magnetic fluid moves due to changes in a magnetic field produced by severalelectromagnets installed above and below a shallow, horizontal acrylic panel in which the magnetic fluid is held. The voltage to each electromagnet is controlled according to sound input by computer processing, making the fluid pulsate like a living thing. In this paper, we propose the concept and design of the magnetic fluid display, and discuss the results of a demonstration of a trialwide-screen projection of the working device. Keywords: Magnetic fluid, display, sound-response, interactive art

1

Introduction

In this paper, we propose and construct a prototype magnetic fluid display in which the magnetic fluid exhibits peculiar shape and motion. The responsive behavior of a magnetic fluid to an applied magnetic field, producing interesting shapes with many protrusions, iswidely known, however there have been few studies that apply magnetic fluid as a display.

2

Concept

Magnetic fluid was placed in a shallow, open acrylic panel. One electromagnet was installed above the panel, and five electromagnets were used as base. Initially, the same poles of the two electromagnets faced inward (Figure 1). A gap between the fluid and the upper electromagnet was providedto allow the magnetic fluid to move freely. The current supplied to the electromagnet was controlled within the range where the relation between the electric and magnetic fields is linear. The voltage to the electromagnets was controlled by a personal computer, with a sound level meter for input.

The shapes that magnetic fluids take can be likened to animals such as sea urchins and hedgehogs.We propose a project that utilizes this ability of a magnetic fluid to move like a living thing. The basic concept is (1) a display that uses a magnetic fluid, (2) changing the shape of the magnetic fluid continuously, and (3) manipulating the magnetic fluid in sync with sound. As an extension of Takeno's device (Takeno, 1999), we increased the number of electromagnets and used a computer tocontrol the voltage applied to each electromagnet synchronously with sound input. We observed the behavior of the magnetic fluid under a variety of conditions and constructed a digitized database of the shape.

10mm

Figure 1: Configuration of electromagnets and magnetic fluid

3.2

Software

3
3.1

Basic System Components
Hardware

A sound level meter and microphone were employed tomeasure environmental sound levels (including the voices of observers), and the data sent to a personal computer at a sampling rate of 5 Hz. The software analyzed the sound level input, and generated voltages for each electromagnet according to the software's processing and distribution algorithm. (Figure 2) As a result, the shape of the magnetic fluid responded to the sound level of the sampledenvironment.
Environmental Sound Sound Level Meter Sound Analysis Magnetic Fluid Control System Magnetic Fluid

Figure 2: Software components

to visualize sound amplitude. This makes it possible to create a fuzzy condition of shape of magnetic fluid by means of environmental sound. In this mode, the power of the upper electromagnet is inversely proportional to the sound amplitude.

4 NewMethods to Control Shape and Movement of Magnetic Fluid
4.1 Variety of Shapes
We initially observed the shape of the magnetic fluid while controlling the voltage of each electromagnet manually, and selected several specific shapes for display (Figure 3).

5

Demonstration

The panel in which the magnetic fluid is held is small, allowing only a few people to observe the display at any one...