From the tiniest pacemaker buried inside the human chest to the next-generation flexible sensors sewn into wearable tech, the demand for compact, efficient energy sources is surging like never before. Yet, the power driving these marvels of modern science often comes with a dark side—environmental toxicity. Most contemporary energy harvesting devices, especially piezoelectric generators that convert mechanical movement into electricity, rely heavily on inorganic materials such as lead zirconate titanate (PZT) and other heavy-metal-based compounds. These materials may be highly effective in electrical performance, but their lack of biocompatibility, non-biodegradability, and toxic nature pose critical challenges.
The situation is particularly dire in biomedical applications, where power sources for implanted devices must operate safely within the human body for extended periods. Traditional batteries require replacement every few years, necessitating risky surgical interventions. The urgent need for sustainable, safe, and biodegradable alternatives has pushed researchers to search beyond the realm of conventional materials. Could nature itself offer a cleaner solution?
Mimosa Pudica: More Than Just a Touch-Me-Not
Enter Mimosa pudica, an unassuming plant known more for its delicate leaf-folding response to touch than its bioelectrical prowess. But beneath its botanical charm lies a powerful secret—its seeds possess remarkable electroactive and piezoelectric properties. Researchers at the Materials Science Centre of the Indian Institute of Technology (IIT) Kharagpur, led by the visionary Prof. Dr. Bhanu Bhusan Khatua, have tapped into this hidden potential. Their innovation? A novel bio-piezoelectric nanogenerator and self-chargeable supercapacitor derived entirely from Mimosa pudica Linn (MPL) seeds.
This groundbreaking device—termed the MSPEG (Mimosa Seed Piezoelectric Generator)—represents a major leap forward in sustainable energy solutions. It is edible, non-toxic, biodegradable, and capable of producing power outputs rivaling many of its inorganic counterparts. Moreover, it can not only harvest mechanical energy but also store it autonomously, eliminating the need for separate batteries or capacitors.
Green Engineering: Where Nature Meets Nano
The team’s primary goal was to create a fully biocompatible and efficient energy-harvesting platform that could seamlessly integrate with electronic systems used in human health monitoring, robotics, and wearable electronics. Central to this innovation is the MPL seed-derived hydrogel, which serves as both a mechanical-to-electrical energy transducer and a flexible medium for energy storage.
Under mechanical pressure—such as the tapping of a finger or bodily movements—the hydrogel undergoes structural deformations. This deformation leads to shifts in electric dipoles within the seed particles, generating electricity through the piezoelectric effect. But what makes this bio-material unique is its composite molecular architecture.
The MPL seed powder is rich in natural compounds: tubulin, glycosylflavones, phenolic ketones, buffadienolides, and glucuronoxylan polysaccharides. These organic molecules are interwoven with numerous hydroxyl (-OH) groups, connected via hydrogen bonding. When mechanical stress is applied, these bonds shift and twist, translating mechanical force into electrical charge with remarkable efficiency.
“Unlike toxic, non-degradable ceramics, Mimosa pudica seeds offer a green, edible, and renewable solution,” explained Dr. Khatua. “We essentially convert a biological reflex into electrical energy, and that’s both elegant and profound.”
Engineering the MSPEG Device
Constructing the MSPEG required a blend of material science, chemical engineering, and biological insight. The team fabricated a flexible nanogenerator by embedding the MPL hydrogel between two electrodes coated with RGO/NiZTO (Reduced Graphene Oxide/Nickel Zinc Titanium Oxide). This composite electrode material was selected for its excellent conductivity, mechanical stability, and compatibility with biological tissues.
But the team didn’t stop at energy harvesting. Using the same MPL hydrogel and electrodes, they engineered a self-chargeable supercapacitor (SCS) capable of storing the harvested energy. The two functions—generation and storage—were unified in a single, seamless bio-device.
The resulting system delivers performance figures that are nothing short of astounding. As a piezoelectric generator, it produces an output voltage of ~13.5 V and a current of ~2.98 μA. The piezoelectric coefficient clocks in at 24 pC/N—a competitive figure by any standard—and the device boasts a conversion efficiency of 40.2%.
As a supercapacitor, the energy density peaks at 125.4 Wh/kg with a power density of 1200 W/kg. Even more impressively, it retains 87.5% of its capacitance after 6,000 charging and discharging cycles, demonstrating superb long-term stability.
From Bench to Body: Real-world Applications
The applications of this device extend well beyond the laboratory. In the field of biomedical implants, the MSPEG could offer a radical alternative to traditional battery-powered systems. Imagine a pacemaker that never needs replacement surgery, powered instead by the body’s own rhythmic movements. Or a neurostimulator that recharges itself through the motion of surrounding tissues.
In wearable technology, the possibilities are just as transformative. Fitness trackers, health monitors, and smart clothing could all benefit from a clean, organic power source that eliminates dependency on heavy metals and disposable batteries. The MSPEG could even be embedded in flexible skin patches or stretchable garments, capturing the kinetic energy of human motion to fuel embedded sensors.
The Internet of Things (IoT) also stands to gain. With billions of sensors anticipated to come online in the coming years, powering them sustainably is a pressing concern. Devices like the MSPEG offer a scalable, eco-friendly path forward—especially in applications where wiring or conventional power supplies are impractical.
Future Directions: Toward Hybrid Energy Ecosystems
Even with its promising capabilities, the MSPEG is still evolving. One area the researchers are actively exploring is improving the structural stability of the hydrogel. While its biodegradable nature is a key advantage, it also means the device could degrade too quickly in certain environments. By tweaking the hydrogel’s formulation, perhaps with naturally derived cross-linkers or nanomaterial reinforcements, the lifespan of the device could be extended without compromising its green credentials.
Another frontier is hybrid energy harvesting. “We’re aiming to integrate piezoelectric, triboelectric, and solar energy generation into a unified platform,” noted Dr. Khatua. “Imagine a single flexible patch that captures sunlight, touch, and friction—all while storing energy for later use. That’s the vision.”
The team is also focused on scaling up production methods. While MPL seeds are abundant, transforming them into high-performance hydrogel structures and coating them with nanoscale materials like RGO/NiZTO requires precise, cost-effective processes. Advances in green chemistry and nano-fabrication could pave the way for commercial viability.
Bioelectrical Renaissance: A Paradigm Shift in Energy
The MSPEG isn’t just a new gadget—it’s a glimpse into the future of bio-integrated electronics. By drawing inspiration from nature and leveraging materials that harmonize with the human body, Dr. Khatua and his team have ignited what could become a renaissance in sustainable electronics.
Their work reflects a broader trend emerging across multiple disciplines: the convergence of biology and engineering. From artificial organs that mimic living tissues to self-healing materials and biodegradable electronics, science is increasingly turning to nature not just for inspiration, but for ingredients. The result is a new kind of technology—clean, conscious, and compatible with life.
Seeds of Change
In a world racing toward digital ubiquity, the need for clean, sustainable energy sources has never been more urgent. The humble Mimosa pudica, long admired for its sensitive leaves, now finds itself at the cutting edge of this revolution. Its seeds, once overlooked, could soon power everything from heartbeats to health monitors, creating a world where energy is not just harvested—but harmonized with life.
As Dr. Khatua eloquently puts it, “It’s time to stop fighting nature and start working with it. The answers to our greatest technological challenges might just be growing in our gardens.”
Reference: Prem Pal Singh et al, Mimosa pudica linn seed derived natural piezoelectric nanogenerator and separator for RGO/NiZTO based high performance supercapacitor, Chemical Engineering Journal (2025). DOI: 10.1016/j.cej.2025.161802.