Haptic feedback devices

When Elitac Weaerables was founded over 11 years ago, we started with developing haptic feedback wearables, taking the technology out of the research & development level and making it market-ready.

These devices, which provide tactile feedback to users, are becoming more and more common in everyday products and markets, ranging from automotive, gaming to healthcare.

At the core of these products are haptic actuators, the components responsible for generating the vibrations that users feel. To enable users to feel vibrations and other tactile sensations, several key technologies are commonly employed.

Among the most common types of actuators used in wearable haptic devices are Piezo actuators, Eccentric Rotating Mass (ERM) motors, and Linear Resonant Actuators (LRAs). Each of these technologies offers specific advantages, making them suitable for different applications.

An exploded view of a cilindrical or ‘pill-shaped’ ERM by Precision Microdrives (Image courtesy of Precision Microdrives)

An exploded view of a coin-style LRA, by Precision Microdrives (Image Courtesy of Precision Microdrives)

Here’s a breakdown of the main technologies powering haptic feedback wearables:

1. Vibration Motors

• Eccentric Rotating Mass (ERM) Motors: ERM motors are widely used in many haptic wearable devices, such as fitness trackers and smartwatches. They create vibrations by spinning an off-centre weight, producing a simple, familiar vibration that users can feel.
• Linear Resonant Actuators (LRAs): LRAs offer more precise (direct or ‘snappy’) and consistent vibrations compared to ERMs. These actuators use a magnetic mass that moves back and forth within a coil, making them ideal for haptic feedback where more controlled and refined vibrations are necessary.

2. Piezoelectric Actuators

• Piezo actuators are known for their precision and rapid response, making them a go-to technology for wearables that need high-frequency, sharp feedback. These actuators work by expanding or contracting in response to electrical signals, producing subtle, detailed vibrations perfect for intricate haptic feedback.

3. TENS (Transcutaneous Electrical Nerve Stimulation)

• TENS technology is used in some wearables to create a tingling sensation by delivering electrical impulses to the surface of the skin through electrodes. While primarily used for pain relief, this technology is also integrated into haptic feedback wearables to provide varied tactile experiences, such as feeling rain drops, slight pressure or touch. .

4. EMS (Electrical Muscle Stimulation)

• EMS technology stimulates muscles directly through electrodes for wearables, placed on the skin, and giving electrical impulses, causing the muscles to contract. This can be used in haptic feedback to simulate more intense sensations, such as muscle movement, or ‘impact’, adding another layer to the tactile experience.

5. Ultrasonic Haptics

• Ultrasonic haptics is an upcoming technology that uses high-frequency sound waves to create tactile sensations in ‘thin air’. This allows users to feel vibrations or textures without direct contact, offering a futuristic approach to haptic feedback in devices, human machine interaction and virtual reality for example.

6. Electro vibration

• Electro vibration technology changes the friction between a user’s finger and a touch surface through electrical signals, creating the sensation of texture. This haptic technology can be used in devices to simulate different material surfaces ( e.g. simulating a texture on the surface of a phone screen), enhancing the user experience.

7. Thermal Haptics

• Thermal stimulation is another technique used in haptic feedback wearables, providing sensations of warmth or coolness. Although not vibration-based, combining thermal haptics with other feedback technologies can significantly enhance the immersive experience.

Each of these technologies plays a critical role in delivering the dynamic and responsive touch experiences that define modern haptic feedback wearables. By carefully selecting and integrating these technologies, developers can create wearables that offer not just functionality, but a truly engaging tactile experience for users.

Selecting the appropriate haptic technology for wearable devices depends largely on the specific needs of the application.

For delicate, low vibration power, but when a high resolution of actuators is needed (for example to experience the haptic sensation of rain drops on the skin), TENS electrodes can be considered.

In case you want to have strong, powerful (even painful) sensations, EMS could be your choice.

But in most of our projects, where we are looking at a great combination of control, robustness, ease of use and strict costs, we go for vibration motors.

• Piezo actuators offer accurate and responsive feedback, but a relatively ‘soft’ vibration and are not so durable, making them less suitable for haptic feedback wearables.
• LRAs provide both precision and robustness, yet at a larger cost. And they are not so powerful, making them a good choice for a wide range of ‘rigid’ consumer electronics, such as mobile phones, where you need only a few of them in one product.
• ERM motors on the other hand are suitable for applications where power, cost and simplicity are the primary concerns. These are our go-to option.

To develop truly effective haptic feedback wearables, one must consider more than just the hardware. It is a delicate balance between hardware, software, integration methods, human factors, vibration patterns, constellations and more. At Elitac Wearables, we specialise in all these facets of haptic wearables and softgoods development.

We can advise you on the most (cost-)effective way to apply haptic feedback in your wearable: we start by evaluating your requirements, the end users’ needs, the application and budget. Then, we take you step by step through the process of optimising the haptic feedback for your wearable.

Our team has over 45 years of combined experience developing haptic feedback wearables. We’ve developed wearables for a variety of domains (Health, Medical, Safety and Sports), in various configurations (belts, vests, shirts, sleeves) and for a wide range of applications.

Different vibration motors (tactors) have different applications. We have used and/or researched the most recent and effective options, helping us advise you on the best type and implementation for your wearable.

By balancing end user requirements, weight, cost, integration options, vibration strength, etc. we can help you develop the most efficient haptic feedback wearable. And thanks to our haptic feedback building blocks, we are able to quickly test and refine new applications.

To ensure our knowledge remains current and help you take advantage of the latest technological developments, we continually research new technology options in our Wearables Lab.

We use haptic interpolation to develop wearables that are more efficient, lighter and cheaper to manufacture.

Haptic interpolation is a concept that allows us to generate haptic sensations anywhere on a patch of skin that is covered by a set of vibration motors – not only underneath or at the location of the vibration motor. In order words, we can generate the sense of vibration or virtual vibration (Av) anywhere on the line of 2 or in the area of 3 actual tactors.

Learn more about haptic interpolation here.

Contact us or consult these scholarly articles to learn more about haptic feedback technology:

Contact us to find out how we can help you to getting wearables in production with efficient and cost-effective haptic feedback.