image: (a-d) Optical images of the tardigrade with Pt patterns transitioning from an anhydrobiosis state to an active state under suitable conditions. Shooting time interval is about 4 min. Images of the tardigrade raising its head (e), twisting (f), rolling (g), and crawling (h) after regaining vitality.
Credit: ©Science China Press
In the rapidly advancing field of nanotechnology, cutting-edge micro/nano fabrication techniques, such as ultraviolet lithography, electron beam lithography, and nanoimprinting, have made it possible to precisely construct complex patterns on the surfaces of various inorganic materials. However, a more challenging scientific question arises: Can we overcome the limitations of traditional substrates and achieve the precise fabrication of microscopic structures on living organisms? While research into bioelectronic devices is flourishing, the harsh process conditions required by traditional micro/nanofabrication technologies are often incompatible with the delicate nature of biological systems. This challenge is particularly pronounced when dealing with dynamic biological interfaces, such as animal skin, which exhibit complex physiological properties. The integration of functional materials into such interfaces remains an unsolved problem.
Recently, Professor Min Qiu's research team from the School of Engineering at Westlake University published a groundbreaking study in Science Bulletin titled "Tattooing Water Bears: Microfabrication on Living Organisms." The research demonstrates the pioneering application of semiconductor thin-film deposition techniques, specifically magnetron sputtering and electron beam evaporation, to create micron-scale functional metal patterns on the surface of living tardigrades. Tardigrades, also known as water bears, are famous for their extraordinary resilience to extreme conditions, including temperatures ranging from -273°C to nearly 100°C, extreme dehydration, intense radiation, high pressure, and toxic environments. The research team ingeniously utilized the cryptobiotic state of tardigrades， during which their metabolism is nearly suspended， to successfully deposit metallic films onto their surfaces. After the deposition, the tardigrades were placed in optimal hydration conditions, allowing them to resume their normal activity. As they did, the metallic films naturally fractured into stripe-like patterns. The different metal modifications imparted unique characteristics to the tardigrades. By exploiting the magnetic properties of the metals, the researchers were able to control their movement，including rotation, rolling, and in-plane displacement， through an applied external magnetic field.
This study paves the way for new advancements in the micro/nanofabrication of living organisms, showcasing the immense potential of bio-inorganic hybrid systems. The use of advanced micro/nanofabrication techniques, such as electron beam lithography and 3D printing, promises to enable the creation of even more intricate patterns on the surfaces of biological organisms. By employing techniques like light, electricity, and heat to precisely manipulate specific areas, this research could lead to significant breakthroughs in fields such as bioelectronic devices and living robots.