Hi! My name is Alex Mazursky from the University of Chicago and today I'd like to talk to you about
our work on a new type of haptic actuator to add tactile output to everyday objects.
This work was done in collaboration with my colleagues Shan-Yuan Teng,
Romain Nith and our advisor Pedro Lopes. What you see here on screen is our new haptic actuator
and it is currently vibrating against the user's finger pad. When we move the finger away we can
see that the vibrating element is a magnet and it is being excited by a coil worn on the fingernail.
Now this is not unlike classical vibration devices such as linear resonant actuators; we too
incorporate the typical coil magnet and spring. However, what is new is that we have mechanically
decoupled the active component, the coil, from the passive components, the magnet and spring.
No wired tethers electronics or batteries are needed within the haptic patches themselves.
Therefore the benefit of this decoupling is that we need only one power source to actuate
any number of passive patches in an environment. We see this as being akin to ubiquitous sensing,
specifically passive approaches, but for haptic output. Let me use some applications to illustrate
how magnetIO works. Here we see a user in their home using magnetIO to control their environment
the user wears our coil on their nail and as they walk inside, they tap the patch on their
door and are met with two vibrations confirming in an eyes-free way that their home alarm is now
disabled. Next the user walks to a patch on their wall that controls their thermostat.
As the user slides their finger to adjust the temperature, magnetIO senses which
part of the patch the user is touching using a magnetometer built into the coil.
According to where they touch, they receive haptic feedback to indicate the setting that
they've selected. One factor that enables placing these patches on many surfaces
is that they are soft and flexible because they are made from mostly silicone.
Next the user picks up their toy which has a heart-shaped patch on its chest. They can feel its
heartbeat with magnetIO. When the toy is shaken the onboard IMU detects the movement and the heart
rate and vibrations speed up accordingly before slowing down again after no movement is detected.
I'll now detail how we implemented this actuator beginning with the nail worn coil which acts as
a wearable power source. This has an IMU with magnetometer, the coil itself, a lipo battery
microcontroller, motor driver, and bluetooth. Our coil is designed to provide strong magnetic forces
while maintaining a compact, lightweight footprint that importantly does not occlude the user's
fingerpad, because we believe it is important to allow the user to still feel their surroundings
in addition to the patches. The final coil design weighs just 2 grams without battery
the user only wears one of these yet they can actuate many haptic patches which I'll describe
now. At the center of the patch is a tactile magnet made from silicone doped with magnetic
powder. This magnet is mounted on two thin beams of silicone that act as springs.
Surrounding the magnet is a cut out and the magnet rests within an air gap.
This allows the magnet to vibrate up and down even when the user compresses the patch with their
finger. In our paper we demonstrate that by tuning the dimensions of the spring and magnet, we can
tune each patch's individual resonant frequency to elicit different tactile sensations more strongly.
Finally the patch's perimeter has four id magnets that enable the patch to be uniquely detected via
magnetometer. The net magnetic field of all magnets encodes a unique 3D signature
to each patch. Using Bluetooth, the actuator can communicate back and forth with the main
application to determine appropriate haptic renderings. Here's how we fabricate our patches,
which are made of two parts: a soft and stretchable magnet made of silicone mixed with
permanent magnetic powder adhered to a flexible silicone mechanism. First, the silicone mechanism
is made by casting silicone into a mold. Next, we fabricate the soft magnets by mixing the silicone
and magnetic powder. The mixture is then cast into a 3d printed mold to shape the magnet. The mold is
then held between two strong permanent magnets and this strong (about 1.1 Tesla) field magnetizes and
aligns the polarities of the individual particles. This process results in a composite with a
strong permanent magnetic field while remaining flexible due to the silicone holding it together.
With a goal of maximizing magnetic field strength due to to produce strong vibrations, we use
a magnetic powder concentration of eighty percent by weight. The haptic patch is then
assembled by adhering the magnets to the mechanism with silicone glue. To summarize,
we designed and evaluated a one-to-many actuator to allow haptic interactions to more easily scale.
We tend to think of magnetIO not necessarily as an end product but as a hardware and fabrication
idea that may inspire more ubiquitous use cases for haptics. Thank you for tuning in to our talk
and please come stop by our demo and check out our paper for more details, thank you!