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, he said. “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. Image: Boréas Technologies.
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.
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. Image: Boréas Technologies.
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 in which 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 × 0.8-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 <300 µs for faster response times; a wide supply voltage range of 3 V to 5.5 V to support integration into most devices; and support for a range of piezoelectric haptic actuators and third-party haptic-effect libraries to speed design-to-manufacture.
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.
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