@INTERACTIONSMAG 88 INTERACTIONS JANUARY–FEBRUARY2020
Envisioning, designing, and implementing the user interface require a comprehensive understanding
of interaction technologies. In this forum we scout trends and discuss new technologies with the potential
to influence interaction design. — Albrecht Schmidt, Editor
FORUM INTERACTION TECHNOLOGIES
They achieve this by computing the
cell geometry (e.g., beam thicknesses)
around the hidden object to deform
differently in order to feel the same to
Since metamaterials originate
in engineering disciplines, most
research is concerned with testing the
mechanical response of the structure.
Therefore, these materials are mainly
actuated by a mechanical force.
However, we think HCI researchers
can push toward interactive
metamaterials by drawing inspiration
from areas within HCI, such as
shape-changing interfaces or self-assembly, to create metamaterials
that can be controlled interactively.
Possible forms of actuation include
embedding mechanisms actuated
by motors, pneumatics, shape-memory polymers, electromagnets, or
thermally responsive, light-absorbing,
or hydrophilic materials.
Metamaterials are designed to
deform in specific locations—the
cells’ flexures; therefore, that is what
needs to be actuated. For inspiration,
in Figure 2 we illustrate one of the few
examples of actuated metamaterials.
The material consists of 3D shearing
cells and is pneumatically actuated
[ 3]. Inflating one of the integrated air
pockets at an edge flattens the incident
faces, which causes the cell to shear. By
selectively inflating combinations of air
pockets, users can control the overall
tilting direction(s) of the material.
We think that interactive
metamaterials will be a trend in the
The ability to design and fabricate
internal structures is powerful, as
it enables users to engineer new
types of materials, with properties
that are not found in nature. Such
materials are known as mechanical
Metamaterials have thousands of
degrees of freedom, allowing them to
cover a large design space. Since
metamaterials are solely defined by
their structure (i.e., their geometry),
they can become a tool for HCI. As
such, we can enable novice users to
participate in and drive this material
In this article, we outline
traditional metamaterials and their
programmable properties, discussing
how metamaterials can be actuated
for interactivity. We then lay out
our vision for future metamaterials.
We believe that metamaterials will
emerge from being materials to
being complete devices. We envision
cell-based metamaterial devices
that sense, process, and output
electronics, purely in the material
Mechanical metamaterials are artificial
structures with unusual properties that
originate in their geometry, rather than
in the specific material from which they
are made [ 1].
Researchers in physics and related
fields have discovered cell designs
that enable materials to change their
volume, absorb shocks, propagate
waves, or enable localized elasticity.
These extreme properties result from
simple building blocks: The material
consists of cells containing parts
specifically designed to deform in
certain ways. Figure 1 illustrates the
structure of these cells, which typically
include bending or rotating parts,
buckling beams, or constrained beams;
it also shows how the macroscopic
material properties are affected.
The capabilities of metamaterials
can be seen in a powerful example: the
“unfeelability cloak” [ 2]. Researchers
designed the material’s geometry such
that an object hidden within the block
of material cannot be felt; touching
the material that hides an object feels
the same as a plain block of material.
Alexandra Ion, E TH Zurich, Patrick Baudisch, Hasso Plattner Institute
→ Metamaterials have thousands
of degrees of freedom, enabling
a material revolution.
→ Their properties are defined
by their geometry, calling for
HCI researchers to investigate
efficient design tools.
→ The bounds of metamaterials’
potential are yet to be found.