HydroHaptics: Soft Surfaces With Real Force Feedback

Touch is one of our most important senses, and it begins to develop even before we are born. It is actually the earliest sense that’s developed in human embryology.

As an integral part of our lives, touch occurs when specialized neurons sense tactile information from the skin and convey it to the brain, where it is perceived as temperature, pressure, pain, and vibration.

Our sensory neurons are highly diverse, with their ends held in varied sensory structures. These neurons work in harmony to detect many different qualities of touch.

As our understanding of the intricate language of touch has grown, so has our ability to recreate it through technology. This is where haptics comes in, an emerging field that translates the sensory richness of human touch into digital and mechanical experiences.

Derived from the Greek word ‘haptein’, which means contact or to touch, haptics refers to sensing and manipulation through touch. It also involves the use of technology to create tactile sensations like vibrations or force feedback. Examples include game controllers, smartphone vibrations, robotic surgery, and virtual reality.

Haptics enables a user to touch and feel distant objects indirectly. Special devices like joysticks and data gloves provide feedback from computer applications in the form of tactile sensation. By providing forced feedback to those interacting with virtual environments, haptics create a bi-directional flow of information.

The Evolution of Haptic Technologies 

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Since its introduction about half a century ago, haptics has evolved into a sophisticated field where sensations like texture, temperature, pressure, and even softness can be engineered into everyday objects. This new generation of haptics promises to bring digital experiences closer to real, physical interaction.

The diverse range of haptic technologies shaping today’s interfaces shows just how much the technology has rapidly advanced.

Smartphones and wearables utilize vibrotactile feedback to generate vibrations, while electrostatic haptics in touchscreens and trackpads create an illusion of texture or friction on an otherwise smooth screen. Thermal haptics simulates temperature changes to bring more realness to virtual interactions.

Force Feedback adds a sense of pressure or motion to make interactions feel more real. Haptic actuators & motors is what makes you feel resistance on a gaming controller or a VR device.

Beyond these, emerging smart materials like electroactive and magnetorheological polymers, which change shape or firmness when exposed to electric or magnetic fields, are enabling flexible haptic feedback.

Then there are piezoelectric haptics for precise and localized feedback using voltage. Small lateral forces applies small lateral forces to the skin, while microfluidic haptics uses tiny fluid channels to simulate touch sensations.

Yet another tech in this growing field is pneumatic and hydraulic haptics, which are used to simulate grip strength, weight, or impact by leveraging air or liquid pressure.

Among these, hydraulic haptics has been gaining a lot of traction among researchers as a high-fidelity haptic technology. This emerging tech, after all, provides powerful and realistic sensations that surpass the capabilities of older vibration-based haptics.

The use of fluids here allows for the creation of strong, precise, and highly dynamic force feedback. Additionally, hydraulic haptic systems can provide swift and realistic thermal sensations by rapidly circulating water with different temperatures. On top of that, hydraulic and pneumatic systems can be integrated into soft, flexible devices, allowing for more natural wearable haptics that reduce user fatigue and maintain dexterity.

With current haptic devices often bulky and rigid, which makes them unsuitable for ubiquitous interaction, researchers have addressed this drawback by developing miniature hydraulic pumps and actuators, thus enabling the creation of small, wearables that are far more practical for everyday use.

For instance, several years ago, researchers from Autodesk Research, the University of Manitoba, and the University of Toronto collaborated to create HydroRing¹, a device worn on the finger to deliver tactile sensations of temperature, vibration, and pressure to allow for mixed-reality haptic interactions. 

When active, this wearable provides sensations with the help of liquid that travels through a thin, flexible tube that’s worn across the fingerpad. In passive mode, it has minimal impact on a user’s dexterity and their perception of stimuli.

More recently, researchers from Georgia Tech introduced their soft haptic ring², which combines pneumatic and hydraulic actuation to mimic softness, roughness, and thermal on the proximal phalanx. This ring, which is made from EcoFlex 00-30 silicone to match the mechanical properties of human skin, enables wearers to use their fingertips to explore their surroundings. 

Its design accommodates the delivery of vibration through pneumatic inflation, thermal sensations through circulating water in a hydraulic circuit, and pressure at the same time. 

Upon evaluating the effectiveness of the ring and rendering techniques, the researchers conducted a user study involving 15 participants. They found an accuracy rate of up to 90% in participants’ ability to match virtual textures to real. Multi-dimensional adjective ratings also indicate that the device effectively communicated distinct tactile sensations across modalities.

A few years ago, researchers from Carnegie Mellon University pushed the technology further by developing hydraulic-based haptics³ thin enough, just 5mm, to be put into an OLED screen to allow for touchscreen notifications to be physically felt. 

The new display tech can allow users to have a more immersive and interactive way to engage with notifications, press buttons, and type on the keyboard. The prototype tech, according to researchers, can further allow for dynamic interfaces on other devices such as music players, games, electric vehicles, and more.

Now, researchers at the University of Bath have developed a responsive new technology⁴ called HydroHaptics that responds to even taps and squeezes.

Why Hydraulic Haptics Outperform Pneumatics (HydroHaptics Explained)

Soft and flexible interfaces offer unique interaction potential but suffer from limited force feedback. Here, pneumatic approaches aren’t suitable because they lack responsiveness and precision while microhydraulic solutions have limited input. 

So, hydraulic systems make for the perfect option. Hydraulic systems make use of liquid as the working fluid, unlike pneumatic approaches that use air, whose compressibility limits speed and accuracy of force and displacement of output. The liquid allows for greater precision as well as more responsive output. 

The current interactive hydraulic models mainly use microhydraulics, which can provide increased control but have volume limitations, which restricts the interface to small buttons, in turn, affecting the input flexibility and form diversity. 

When designing hydraulic interactive systems, one also has to deal with leakage, limited back-drivability, and the need for specialised components, which make it harder to achieve them.

So, the researchers have created HydroHaptics, a new system that enables high-fidelity force feedback on deformable interfaces through hydrostatic transmission. This platform is capable of boosting the quality of force feedback on soft interfaces, while maintaining the qualities that enable rich user experiences i.e., flexibility, softness, and freedom of input.

This technology comes with several advantages. For starters, it is powered by a brushless DC motor and doesn’t need pumps, valves, and regulators. By utilizing the availability, affordability, and control options of the compact motor, the researchers can create force-feedback effects on HydroHaptics. 

Being designed with fewer components to be scalable reduces the system’s susceptibility to leaks while making it adaptable to larger interfaces. Most components used in the system are also either off-the-shelf parts or 3D-printed.

On top of it, HydroHaptics is intrinsically bidirectional to enable both the sensing of force input interactions and deliver force feedback. What this means is that, the novel technology enables two-way communication between a person and the object that they are holding or wearing. 

Together, all these benefits provide unique opportunities to explore haptic interactions on soft interfaces and develop novel deformable devices.

Now, HydroHaptics is an open-source system with a sealed hydraulic cell, which contains a fixed amount of liquid, which is incompressible and hydraulically couples the two flexible surfaces of the cell. This enables the transmission of bidirectional force between them.

A linear mechanical actuator acts as the haptic engine, which can provide force feedback by displacing the fluid, transmitting force to the deformable interface. To allow the interface to deform, the same engine moves in response to the force applied to the deformable interface while maintaining the pressure within the hydraulic cell, which is adjustable to render different stiffness levels.

Using this approach, users can feel vibrations, sharp clicks, and varying resistance while the surface keeps its natural softness and flexibility, no matter how one presses, pinches, or twists it, “something that, until now, simply hasn’t been possible,” said study co-lead James Nash, who’s a Bath Computer Science PhD student.

So, an individual can pinch, tap, or twist an object like a pliable computer mouse, an item of clothing, or a cushion, and that object will respond in an expressive and meaningful way, for instance, by dimming light, sculpting on a screen, or changing the TV channel.

User input can also be sensed by monitoring the internal pressure.

“Input from the user is sensed by the system through the object, and the user then feels the system’s haptic response through the deformable surface.”

– Study lead Professor Jason Alexander from the Department of Computer Science at Bath.

This way, HydroHaptics allows for distinct haptic experiences on soft, deformable interfaces, which are currently impractical through existing approaches.

With HydroHaptics, the researchers are opening the doors to exciting opportunities for touch-based interactions with mundane items. The tech can greatly benefit gaming, wearable tech, medical simulation, product design, and other fields.

The Next Wave of Human-Computer Interaction

The team of computer scientists from Bath presented their study on HydroHaptics at the  ACM Symposium on User Interface Software and Technology (UIST ’25) a few weeks ago, where the paper received an honourable mention award.

In its existing form, the system is in a cylindrical shape, at the top of which, is a deformable dome made of silicone, which makes the exposed top surface of the cell, whose bottom is also sealed with a flexible silicone membrane. Right below the cell is a pressure sensor and a screw carriage, which is powered by the DC motor.

When the user interacts with the dome, as in pressing or squeezing it, they displace the water, causing it to press down on and extend the lower membrane. The sensor detects the resulting increase in pressure and matches it to the corresponding gesture and command associated with it.

To provide tactile feedback, the device uses the motor to compress the cell from below, which pushes the dome upwards against the user’s finger, thus creating a sensation of an oscillating vibration, a distinct click, or a tensioned pushbutton.

To demonstrate the capability of HydroHaptics in enhancing interaction through fine-grain force feedback, the team integrated it into four everyday applications. 

A force-augmented, deformable computer mouse with a soft, silicone dome that allowed users to sculpt digital objects on a screen by pressing and deforming the mouse surface. 

A small interactive cushion that delivers haptic feedback while maintaining its softness. A HydroHaptic pouch was placed into the cushion to control smart devices when pressed or squeezed.

A backpack that provides on-body force feedback through the straps. It delivered smartphone notifications through shoulder taps and presses, which can also be used for navigation.

A 3D-printed force-augmented joystick is improved with HydroHaptic technology to boost video game immersion. The haptic feedback was given to players during gameplay to simulate tension, resistance, or sharp impact.

These applications demonstrate the integration of quality haptic feedback in soft, flexible interfaces and objects for the first time. And the team sees a lot of potential for their technology across a wide range of interactive devices.

“Our experiments show this is a reliable system for allowing a human to interact with soft objects in a meaningful way that will enhance the way we live and work.”

– Professor Jason Alexander

To illustrate HydroHaptics’ potential, he gave the example of a user feeling physical effects in the cushion one is leaning on, which mirrors what’s happening on the TV in front of them. For instance, the vibration in the cushion when a car drives on a bumpy road on the TV, or the cushion going solid when someone hits a hard wall. Another example is that of the backpack wearer, who doesn’t need their phone for navigation as the straps will guide them through gentle squeezes to the shoulder.

“These are just two of the many ways this technology could be integrated into our lives in the not-too-distant future.”

– Alexander 

To evaluate the performance of their technology, the team ran a series of technical assessments using a high-precision robot arm and conducted a user study. During the study, the team demonstrated HydroHaptics’ ability to create distinct haptic effects with an average identification accuracy of 82.6% across all effects and 92.8% on the most distinct effect. 

While other research teams are also working on soft, deformable interfaces, having produced prototypes that show highly localized sensations or different levels of low-fidelity feedback, they haven’t achieved HydroHaptics’ level of scale, precision, and resolution.

The team believes HydroHaptics products can be market-ready soon, if the interest in their tech is any indication. “Given sufficient resources, it wouldn’t be unrealistic for this to be in a product in a year or two,” said Professor Alexander.

But of course, the team needs to first refine the haptic engine so that its bulk can be reduced and made suitable for commercial applications.

The system is not without its technical limitations either. As the paper noted, air can get trapped within the hydraulic cell or leak into the system over time, which can reduce its performance. Additionally, high output pressure creates the need for significant power, which can lead to thermal issues.

When it comes to the haptic engine, the team’s approach depends on it being rigid, and while it can be separated through a flexible tubing, it must stay connected to the interface, which isn’t always feasible for fully deformable interfaces. The study noted:

“HydroHaptics represents a meaningful step toward the long-term goal of achieving fully deformable haptic force feedback systems, and future work should aim to reduce the number and size of rigid components.” 

Investing in Haptics Tech

Texas Instruments (TXN -5.6%) is a semiconductor giant that develops analog and embedded processing chips for various markets including personal electronics, automotive, communications equipment, industrial, and enterprise systems.

TI is also a major player in the haptics industry, providing integrated solutions that include haptic drivers, touch screen controllers, and software libraries for generating tactile feedback in consumer electronics and industrial products.

Texas Instruments (TXN -5.6%)

With a market cap of $160.5 billion, TXN shares are currently trading at $176.93, down 5.83% YTD but up 26.4% since the April low. TXN shares actually hit an all-time high (ATH) at $221.69 in July.

Texas Instruments has an EPS (TTM) of 5.28 and a P/E (TTM) of 33.46. A dividend yield of 3.22% is offered to shareholders. On Oct. 16, TI declared a quarterly cash dividend of $1.42 per share of common stock. The dividend was raised by 4% last month, marking 22 consecutive years of increases.

Recent Results (Q2 2025): Texas Instruments reported $4.45 billion in revenue (+16% YoY, +9% QoQ), ~$1.30 billion in net income, and $1.41 EPS. Management guided Q3 revenue to $4.45–$4.80 billion. Free cash flow (TTM) was ~$1.8B in the Q2-2025 report.

Conclusion

As the world of haptics expands and grows, HydroHaptics represents a paradigm shift in how we will touch and be touched by technology. By combining soft, deformable interfaces with precise force feedback, the technology is opening the door to richer, more natural interactions with our devices and environments. 

From immersive entertainment to medical training and smart homes, this technology could redefine how humans and machines communicate.

References:

1. Han, T., Anderson, F., Irani, P., & Grossman, T. (2018). HydroRing: Supporting mixed reality haptics using liquid flow. In Proceedings of the 31st Annual ACM Symposium on User Interface Software and Technology (UIST ’18) (pp. 913–925). Association for Computing Machinery. https://doi.org/10.1145/3242587.3242667
2. Sanz Cozcolluela, A., & Vardar, Y. (2025). Generating multimodal textures with a soft hydro-pneumatic haptic ring. Elsevier BV. https://doi.org/10.2139/ssrn.5170637
3. Shultz, C., & Harrison, C. (2023). Flat Panel Haptics: Embedded electroosmotic pumps for scalable shape displays. In Proceedings of the 2023 CHI Conference on Human Factors in Computing Systems (Article 745). Association for Computing Machinery. https://doi.org/10.1145/3544548.3581547
4. Nash, J. D., Sauvé, K., van Riet, C. M., van Oosterhout, A., Sharma, A., Clarke, C., & Alexander, J. (2025). HydroHaptics: High-Fidelity Force-Feedback on Soft Deformable Interfaces using Hydrostatic Transmission. In A. Bianchi, E. Glassman, W. E. Mackay, S. Zhao, J. Kim, & I. Oakley (Eds.), Proceedings of the 38th Annual ACM Symposium on User Interface Software and Technology (UIST ’25) (Article No. 59). Association for Computing Machinery. https://doi.org/10.1145/3746059.3747679