Boréas’ piezoelectric actuator driver chip opens up new opportunities for HD haptics in next-generation wearables and other battery-powered consumer devices

By Gina Roos,
editor-in-chief

Imagine shopping at an e-commerce site and you can “feel” the item
that you’re considering purchasing right on your mobile device. Maybe it’s the
wool material of a winter hat or the texture of wood on a kitchen table.
Startup Boréas Technologies’ new piezoelectric
actuator driver IC could be the enabler to make it possible in the future, with
some help from haptics software applications.

Haptics, or tactile, feedback is all about improving the user’s
experience on mobile phones, tablets, and other consumer devices. Most of these
applications use inertial haptics actuators like eccentric rotating mass (ERM)
motors and linear resonant actuators (LRAs). High-definition (HD) haptics is
tactile feedback on steroids, boosting the vibrational effects for better
feedback. These HD haptics applications are using piezoelectric (piezo)
actuators and driver ICs thanks to their advantages over traditional ERM and
LRA technologies.

“Haptics is everything you can touch,” said Simon Chaput, founder
and CEO of Boréas Technologies, a developer of ultra-low-power haptic
technologies. In a simple example, a call is received on a cellphone and it
vibrates and communicates with touch, but haptics can be much more than that. “The
vision for the future is to be able to represent texture on the screen of
different devices — for example, if you’re shopping on an e-commerce site and
you want to touch the fabric. We think in five to 10 years, you’ll be able to
swipe your finger across the touchscreen and feel the fabric.

“It could be a differentiator, for example, for smartphones,” he
added. “It becomes more important for companies to differentiate their
products. Almost all smartphones are the same size and look alike. If you add
haptics, and with software, you can define a different user experience, which
is really not possible now.”

Boréas Technologies potentially opens up new design opportunities
for realistic touch interfaces in applications such as wearables and
battery-powered consumer devices with its new BOS1901 piezoelectric driver IC,
based on the company’s CapDrive technology platform.

Boréas, a fabless semiconductor company, is a spin-out from
Harvard University, founded in 2016 in Bromont, Québec, Canada. CapDrive,
originally developed at Harvard University for ultra-thin cooling fans, is a
proprietary scalable piezoelectric actuator driver architecture that offers
greater energy efficiency, low heat dissipation, and rapid response times,
according to Boréas. The BOS1901 piezoelectric haptic driver is Boréas’ first
production-ready device based on the research started at Harvard University.

Fig. 1: The
BOS1901 is a single-chip piezo actuator driver based on Boréas’ CapDrive
piezoelectric actuator driver technology.

The market for haptic actuator driver ICs is big, estimated to
reach $26.5 billion by 2022, according to BCC
Research
. Boréas’ product takes aim at the fastest-growing
segment — piezoelectric haptic components — among the haptic interface
technologies, which includes ERM motors and LRAs. These traditional
architectures for haptics are said to be limited by higher power consumption,
larger size, and slower response time.

Even though piezoelectric is the fastest-growing segment among the
haptic interface technologies, there are still challenges.

“Piezoelectric drivers harvest energy from ambient sources,
reducing the need to constantly seek an external charge,” said Michael Sullivan, senior editor of BCC
Research. “Most of these drivers, however, still require more power than
the cost and form factor can accommodate.”

One of the biggest design challenges of haptic technologies,
particularly for mobile and consumer electronics applications, is power
consumption. “The key is power consumption to accommodate the reduced form
factor in these device types,” said Sullivan.
“As with most applications of actuators and drivers, the design consequences of
excessive power requirements can increase the cost and feasibility of the
device while also preventing its full utility in the consumer market.”

Sullivan believes that the Boréas piezoelectric actuator driver
chip solves some of these challenges. “The driver offers one of the lowest-power
solutions in this form factor adapted for both consumer and business markets,”
he said.

Designed for HD haptic feedback in battery-powered devices that
range from smartwatches and smartphones to game controllers, the new BOS1901 IC
meets the performance requirements and power demands of haptic applications
while delivering big power savings.

Power consumption is a problem in haptics, agreed Chaput. Haptics
technology consumes a lot of power, requiring more energy-efficient power ICs.

Boréas said that the new device enables realistic haptic feedback
without draining a device’s battery. The biggest advantage of the BOS1901 is
the power savings for piezoelectric actuators. The BOS1901, a low-power,
high-voltage driver for piezoelectric actuators, provides a 10× power savings
compared to its nearest piezoelectric competitor and a 4× to 20× power savings
compared to traditional haptic technologies, including LRAs and ERM motors.

Boreas BOS1901 dev kit

Fig. 2: The
BOS1901-Kit includes two 
BOS1901 high-voltage piezo drivers
compatible with a wide range of piezo actuators, along with two piezo actuators
to jumpstart the designer’s evaluation.

One of the main problems with piezo haptics is not from the
actuator technology — it’s the driver technology, said Chaput. “Compared to
other technologies [such as ERM and LRA]
and other piezos using other types of drivers, we can reduce power
by 6× to more than 10× and provide better haptics.”

But what about cost? Chaput said that it’s going to cost more than
ERM, the cheapest and most basic solution, but it provides much better haptics
and the cost is comparable to an LRM solution. All mid- to high-end devices
gave up on the ERM technology, and the current solution being used, LRA, doesn’t
provide the correct user experience, he added.

Sample use case

Midé Technology Corp., an engineering, design, and manufacturing
solution provider in Medford, Massachusetts, has been working with the new
Boréas piezo chip due to its lower power and efficient amplification stage.

“We’ve been working on haptic or tactile feedback systems for a
number of years,” said Jared Keegan, Midé’s vice president of business
development.

Although one
of the benefits of piezo is that it’s very low power, some of that benefit
is lost in battery powered applications where you must
often boost lower voltages up to the higher voltages required to actuate the piezoelectric
element itself, explained Keegan. This stage,
where you boost a lower voltage to a higher voltage to induce the piezo to work
appropriately, weren’t that efficient using previous chips, he said.

Midé is
using Boreas’ chip to build a prototype wearable shirt, which integrates more
than 20 actuators. The wearable garment targets simulation, training, and
operational uses in military/aerospace applications, specifically as a project
for the Department of Defense (DoD) to help pilots maintain situational
awareness when visuals are degraded. The company’s patented actuator
array architecture for wearable haptics and tactile feedback uses smart
individually addressable tactile actuators, each with piezo, bus transceiver,
onboard intelligence and a piezo boost driver IC packaged together.

The wearable shirt can be worn by a pilot in a simulator or in an
aircraft specifically to give them vibrational information — tactile or haptic
feedback, said Keegan.

For example, if you veer off the side of the road onto the rumble
strip, which vibrates the car, the vibration tells you to come back on the road
in a very simple sense, he said. “In a similar manner, this garment would
provide an array of different intuitive tactile cues for the pilot.

“In our previous generation, using a competitor’s chip, it took
more power to drive the actuators and it was limited to how many actuators that
you could drive at one time,” said Keegan.

Along with Midé’s own development effort to intelligently drive
all of the actuators — improving the technology to communicate “smartly” to a
host of actuators — Keegan said that it was able to lower the total system
power in the design. This translates into either driving more actuators or
using the same number of actuators at less power to improve the battery life.

“For any battery device, you want as low power as possible,
especially when you have more than one actuator,” said Keegan. “You pay that
[power] penalty for every actuator, so it has helped us out a lot.”

“We have created prototypes that are much better from a size, weight,
and power (SWaP) perspective,” he added.

“Across markets, whether it’s mobile phones, tablets, watches, or
other handheld devices, there is going to be a significant benefit by using a
piezoelectric haptic feedback actuator, and Boreas’ chip is going to be an
enabler for those markets. Gaming and VR are also very interesting growing areas for
haptic feedback,” said Keegan.

Other advantages

A small package size is also a differentiator, with the BOS1901
housed in a 4 × 4 × 8-mm footprint. A small footprint is very important in
smartwatches and any application tight on space, said Chaput.

Another feature that is very interesting is low latency, which
means that the chip can go from a complete power-down to startup in a very
short time — up to 7× faster than the nearest competitor, he added.

The BOS1901 offers several advantages over legacy technologies,
including low power consumption, which lowers the frequency of battery
recharging; a startup time of

In addition, the device can drive one bipolar piezoelectric
actuator or two unipolar piezoelectric actuators, which reduces the number of
drivers needed and, thus, cutting board space.
Key specs include:

  • 1.8-V to 5.0-V digital I/O supply
  • Up to 35-MHz SPI
  • 64 samples internal FIFO interface
  • Multiple drivers on the same communication bus

Thanks to these advantages, the new technology is promising in the
area of next-generation HD haptics. Haptic feedback today, like those found in
devices like smartphones or game controllers, delivers information to users via
vibrations, pulses, and motion, whereas HD haptic feedback in user interfaces
promises to deliver enhanced haptics to the user via surface “textures” such as
the feel of fabric or wood.

Chaput admits that this functionality is still a good five to 10
years into the future. But the possibility of new opportunities with this kind
of haptic feedback is only limited by a designer’s creativity.

Boréas offers a plug-and-play development kit, the BOS1901-Kit,
for interactive piezoelectric haptic feedback. Two commercial piezo actuators
are included in the kit: Midé Technology’s PPA-2014 and TDK’s
PowerHap 2.5G. Production volume is scheduled for the
first quarter of 2019.

As a startup, there are often concerns around production-volume
supply. Chaput said that the company is partnering with a large foundry to
mitigate any possible supply risks often associated with startups. The company
will be “able to supply millions of chips easily, so ramping up volume
production is not a problem,” he said. Boréas is also in the process of
developing a distribution network to sell its chips.