You must’ve heard the terms Haptic Energy or Haptic Feedback. The term has been used frequently in these times of wearable tech. In 2024, a humongous volume of 534 million wearable units were shipped globally.
These units included a wide variety of electronic device items such as smartwatches, fitness trackers, headphones, extended reality devices, that is, VR headsets, and augmented reality glasses. With the emergence of wearable electronics, a paradigm of haptic energy has emerged.
Over the last four decades, the main communication method in electronics has been audible or visual feedback, with the main language of communication being sound and light. But today, haptic feedback has become another way for electronics to communicate with human beings, using their sense of touch.
Smartphones, smart watches, fitness trackers – all these portable battery-powered systems could use haptics. As an application, it has its place well-established in consumer, industrial, and automotive applications, such as a smartphone, tablets, mice, ATM machines, and automotive infotainment systems.
Now, a team of researchers has successfully applied haptic energy to wearables¹. While speaking about the purpose of their research and the importance of what it could achieve, Saad Khan, co-corresponding author and INVISTA Professor of Chemical and Biomolecular Engineering at NC State, had the following to say:
“We then began a series of experiments to explore whether we could use amphiphiles to modify materials and incorporate them into haptic energy harvesters.”
To learn more about the research and its achievements, we will delve deeper into it in the next segment.
Compressing Slippery Surface-Assembled Amphiphiles for Tunable Haptic Energy Harvesters
Source: NC State University
The researchers realized that a recurring challenge in extracting energy from ambient motion was that devices must maintain high harvesting efficiency and a positive user experience when their interface is going through dynamic compression. The researchers showed that small amphiphiles could be used to tune friction, haptics, and triboelectric properties by assembling them into specific conformations on the surface of materials. Amphiphiles are molecules that are often used in consumer products to reduce friction against human skin. For instance, these molecules are often incorporated into diapers to prevent chafing.
While speaking about the quest and motivations that drove it, Lilian Hsiao, corresponding author of a paper on the work and an associate professor of chemical and biomolecular engineering at North Carolina State University, had the following to say:
“We set out to develop a model that would give us a detailed fundamental understanding of how different amphiphiles affect the surface friction of different materials.”
Researchers saw that molecules that formed multiple slip planes under pressure, especially through π-π stacking, produce 80 to 90% lower friction than those that form disordered mesostructures. As a result, the researchers proposed a scaling framework for their friction reduction properties that account for adhesion and contact mechanics.
In achieving their purpose, the researchers realized that amphiphile-coated surfaces tended to resist wear and generate distinct tactile perception, with humans preferring more slippery materials. On another level, the researchers could also enhance triboelectric output through the use of amphiphiles with high electron affinity.
Altogether, molecules that could self-organize into slippery planes under pressure represented a facile way to advance the development of haptic power harvesters at scale. To explain in more practical terms, researchers found that it was possible to use amphiphiles to create wearable fabrics with slippery surfaces that felt good against human skin.
Moreover, the researchers found that some amphiphiles, owing to their inherent electronic properties, could work as electron donors. These electron-donating amphiphiles, when incorporated into wearable materials, resulted in comfortable material capable of generating electricity through friction produced by rubbing against human skin or other surfaces.
Summarily, as Hsiao highlighted, in their proof-of-concept testing, the researchers found these amphiphile materials not only felt good on the skin but could generate up to 300 volts, which was remarkable for a small piece of material.
According to Saad Khan:
“We’re interested in doing more to make use of these materials, such as exploring how they can be incorporated into existing haptic devices. And we’re open to working with industry partners to identify new applications.”
While research and its industrial adoption must go hand in hand, there are several companies that are already deep into researching products that would harvest energy from the body to run wearable tech devices. In the following segments, we discuss a couple of such pioneering companies that could benefit from research like the one we discussed.
1. Medtronic PLC (MDT +1.61%)
One of the companies that has worked extensively with wearable tech is Medtronic. This large public med-tech giant is perhaps one of the best-positioned ones to leverage haptic energy harvesters.
One of Medtronic’s most significant offerings is the BioButton, a multi-parameter, medical-grade wearable device designed for intelligent patient monitoring. It provides trending data on key vital signs and biometrics, serving as an early indicator of patient decline.
Designed for continuous monitoring of the leading indicators of patient decline, the monitor could measure resting respiratory rate, resting heart rate, skin temperature, and a series of biometrics. The wearable made it possible for researchers to explore trending data to help clinicians identify patients who may need clinical intervention and those who may be ready for discharge.
In 2022, Medtronic entered into a strategic partnership with BioIntelliSense, a continuous health monitoring and clinical intelligence company, for the exclusive U.S. hospital and 30-day post-acute hospital-to-home distribution rights of the BioButton.
During the announcement of the partnership, Frank Chan, Ph.D., president of the Patient Monitoring business, which was a part of the Medical Surgical Portfolio at Medtronic, had the following to say:
“Our vision is to empower clinicians and patients with actionable insights to personalize care — anytime, anywhere. Through our collaboration with BioIntelliSense, we will support continuous, connected care from in-hospital to home and expand our reach to help more patients in more places than ever before.”
Medtronic plc (MDT +1.61%)
Being one of the most significant med-tech companies in the world, Medtronic is perhaps the most well-positioned to benefit from research like the one we have discussed. In May 2024, Medtronic announced financial results for its fourth quarter and fiscal year 2024. The company reported a Q4 revenue of $8.6 billion, an increase of 0.5% as reported and 5.4% organic. The company reported an FY 24 revenue of $32.4 billion, an increase of 3.6% as reported and 5.2% organic.
2. Philips
Like Medtronic, another tech giant that has put a lot of R&D efforts into developing cutting-edge wearable tech is Philips. The patient-worn monitoring solutions from Philips give patients the freedom to move around the care unit or the hospital.
Designed for comfort, Phillips’ patient-worn devices use wireless technology to transmit data and alarms to where they’re needed, such as a central nursing area, remote observation area, or a caregiver’s mobile device. The devices feature a range of measurement capabilities to address the clinical needs of general and intermediate-care patient populations.
The brand name of the product is Intellivue MX40. Users can operate the IntelliVue MX40 with disposable AA batteries or a single Philips rechargeable battery. The device supports the ability to obtain derived 12-lead ECG information while continuously monitoring ST and QT, FAST SpO2, and impedance respiration. With up to 5 screen formats, the information one needs is readily available with a single touch.
The device features a wireless short-range connection to IntelliVue monitors to capture vital signs or for more comprehensive viewing. The device features a unique cable connector designed to reduce the collection of soil and liquids and a case design that withstands high-level disinfectants, including periodic sterilization.
According to the latest available information, in 2023, Philips registered 18.2 billion Euros worth of sales with 6% comparable sales growth and an adjusted EBITA margin of 10.6%
While large tech companies like Medtronic and Philips are developing products that can benefit significantly from Haptic Energy Harvesters, several other research organizations have been working along the same lines.
In the coming segments, we discuss a few such research studies that have the potential to revolutionize applications in this field.
Electronic Prototype that Harvests Energy from Body Heat and Turn it Into Electricity
In September 2024, reports came out of University of Washington researchers developing a flexible, durable electronic prototype capable of harvesting energy from body heat and turning it into electricity to power small electronics, such as batteries, sensors, or LEDs. The device’s resilience keeps it usable even after it has been pierced several times and stretched up to 2000 times.
According to senior author Mohammad Malakooti, UW assistant professor of mechanical engineering:
“When you put this device on your skin, it uses your body heat to directly power an LED. As soon as you put the device on, the LED lights up. This wasn’t possible before.”
To elaborate functionally, the device has three main layers. The layer at the center has rigid thermoelectric semiconductors that convert heat to electricity. These semiconductors are surrounded by 3D-printed composites with low thermal conductivity, which enhances energy conversion and reduces the device’s weight.
Further, to provide stretchability, conductivity, and electrical self-healing, the semiconductors are connected with printed liquid metal traces. Moreover, embedded liquid metal droplets in the outer layers improve heat transfer to the semiconductors and maintain flexibility because the metal remains liquid at room temperature.
While speaking about the benefits of the technology and its larger purpose, Mohammad Malakooti had the following to say:
“This could be especially helpful in data centers, where servers and computing equipment consume substantial electricity and generate heat, requiring even more electricity to keep them cool. Our devices can capture that heat and repurpose it to power temperature and humidity sensors.”
He added:
“This approach is more sustainable because it creates a standalone system that monitors conditions while reducing overall energy consumption. Plus, there’s no need to worry about maintenance, changing batteries, or adding new wiring.”
In the future, the researchers were optimistic about the technology finding application of this technology in virtual reality systems and other wearable accessories to create hot and cold sensations on the skin or enhance overall comfort.
Three years before this, in October 2021, researchers at CU Boulder had a similar breakthrough. We will look into that research in the next segment.
Click here to learn about the smart fabric that converts body heat into energy.
Wearable Device that Turned the Body Into a Battery
Researchers at CU Boulder came up with a new, low-cost wearable device that could transform the human body into a biological battery.
One of the most enticing features of the device was that it was stretchy enough to be worn as a ring, a bracelet, or any other accessory that touched the wearer’s skin. It tapped into a person’s natural heat—employing thermoelectric generators to convert the body’s internal temperature into electricity.
The device could generate about 1 volt of energy for every square centimeter of skin space—less voltage per area than what most existing batteries provided but was still enough to power electronics like watches or fitness trackers.
The researchers leveraged a base made out of a stretchy material called polyimine and then stuck a series of thin thermoelectric chips into that base, connecting them all with liquid metal wires. The final product looked like a cross between a plastic bracelet and a miniature computer motherboard or maybe a techy diamond ring.
The solution was flexible enough for its power to be boosted by adding in more blocks of generators. One of the researchers compared the solution with the way we deal with Legos:
“It’s like putting together a bunch of small Lego pieces to make a large structure. It gives you a lot of customization options.”
Ultra-Thin, Flexible Film Powering Next-Gen Wearables
A more recent research, led by a team from the Queensland University of Technology, developed an ultra-thin, flexible film that could power next-generation wearable devices using body heat, eliminating the need for batteries.
Additionally, the technology could cool electronic chips, helping smartphones and computers run more efficiently.
According to Professor Zhi-Gang Chen, whose team’s new research was published in the prestigious journal Science:
“Flexible thermoelectric devices can be worn comfortably on the skin where they effectively turn the temperature difference between the human body and surrounding air into electricity.”
While speaking about the potential application of this technology, Professor Chen highlighted that it could be applied in a tight space, such as inside a computer or mobile phone, to help cool chips and improve performance.
Other applications included personal thermal management, where body heat could power a wearable heating, ventilating, and air conditioning system. The researchers cited some challenges that were also true for similar innovations. These challenges included limited flexibility, complex manufacturing, high costs, and insufficient performance.
However, the research we’re currently discussing offered some solutions when it came to cost management. While most research in this area had focused on bismuth telluride-based thermoelectrics, valued for their high properties that convert heat into electricity, the team introduced a cost-effective technology for making flexible thermoelectric films by using tiny crystals, or “nano binders,” that formed a consistent layer of bismuth telluride sheets, boosting both efficiency and flexibility.
More specifically, the team deployed “solvothermal synthesis,” a technique that formed nanocrystals in a solvent under high temperature and pressure, combined with “screen-printing” and “sintering.”
The researchers created printable A4-sized film with record-high thermoelectric performance, exceptional flexibility, scalability, and low cost. The screen-printing method allowed large-scale film production, while sintering heated the films to near-melting point, bonding the particles together.
The solution could also work with other systems, such as silver selenide-based thermoelectrics, which were potentially cheaper and more sustainable than traditional materials.
Concluding Words
Successful energy management has evolved as the most critical threshold that can make or break a technological solution. Energy harvesting techniques that utilize body heat to power wearable tech are the most promising approach in this direction, ensuring efficiency without requiring external energy or power. The solutions resulting from these efforts are sustainable. With increasing adoption, it is now only a matter of time before these solutions become fit for scaled-up commercial production, reducing costs and improving availability.
Study Reference:
1. Jani, P. K., Yadav, K., Derkaloustian, M., Koerner, H., Dhong, C., Khan, S. A., & Hsiao, L. C. (2025). Compressing slippery surface-assembled amphiphiles for tunable haptic energy harvesters. Science Advances, 11(3), eadr4088. https://doi.org/10.1126/sciadv.adr4088
