Intelligent Design — In Miniature
A recent research award from the European Research Council supports the study of some of the world’s tiniest vertebrates, hoping to unravel what is considered the mystery of animal miniaturization. Small vertebrates may be a thousand times larger than single-cell organisms, but they occupy a region of parameter space that presents uniquely fascinating properties.
Within a single cell, the multitude of interacting organelles are basically large, complex molecules with specific structures allowing them to carry out particular functions. Interactions proceed along the lines of biochemistry. At the size scale of insects, spiders, and small vertebrates, multicellular components form the functioning structure of the living organism. At such miniature size scales formidable engineering challenges are encountered, appreciated within the field of micro-robotics.
Among the contenders for the smallest vertebrates are flea toads.
Just seven millimetres long, flea toads are among the smallest vertebrates on Earth. Despite their diminutive size, their organs and functions hardly differ from animals a thousand times larger. While examples of extreme miniaturisation abound in nature, just how these creatures get so small remains a scientific mystery.
Serious Engineering Challenges
Is it easier to construct a micro-robot or a macro-scale robot? From an engineering point of view, the smaller size scale introduces serious challenges.
Over the past years, the field of miniaturized robotics has rapidly expanded with many research groups contributing to the numerous challenges inherent to this field….However, despite all efforts and many available soft materials and innovative technologies, a fully autonomous system-engineered miniaturized robot (SEMR) of any practical relevance has not been developed yet….A careful examination of current SEMRs that are physically, mechanically, and electrically engineered shows that they fall short in many ways concerning miniaturization, full-scale integration, and self-sufficiency.
Physics principles concerning the mechanical properties of a system change appreciably with increasing miniaturization. Designing a functioning miniaturized system involves more difficulties than simply scaling down the physical size of every component.
As the systems become smaller, the relative forces that act on the system change dramatically, and the robots experience an increase in friction and adhesion. At the same time, weight and inertia gradually become irrelevant. Changes in fluid mechanics and stochastic motion challenge fundamental engineering notions of how mechanical elements move and interact. These physical effects form a crucial factor in designing and operating robots on a small scale.
Ingenious Solutions to Miniaturization
Tiny living creatures abound, demonstrating ingenious solutions to miniaturization that surpass human technological skills. A short list of the challenges that engineers face in trying to make robots the size small-scale life is given below, and includes adequate power, “intelligence,” and sensor-feedback-control mechanisms.3
“One of the challenges in designing capable SEMRs [system-engineered miniaturized robots] is the limited power budget, as existing propulsion methods require significant power, and the energy-storage systems (ESSs) are extremely difficult to downscale into the submillimeter range.”
“However, with miniaturization of the robot’s size, it is also clear that robots lose the ability of on-board intelligence and become limited in functionalities.”
“Current SEMRs have no energy on-board and lack any continuous feedback-controlled sensing, actuation, data processing, and communication.”
Observing a tiny spider that built its web in the corner of a window in my house was what set me to thinking about the amazing design in miniature creatures. Although this little critter had taken up its residence on the inside of the window, I let it alone out of fascination. I had to look closely to even see the spider, barely a millimeter or two in size. And yet it had woven this little web stretching several centimeters across the corner of the windowsill. For comparison, this would be like me using rope to construct a web the size of a football field.
This little arachnid warrior had managed to capture prey in its web (several of their remains could be seen) and presumably nourished itself thereby. Think about the capabilities packed into this tiny creature. It’s mobile and autonomous. It can see its surroundings and make decisions based on that sensory input regarding where to make its web. It manufactures and dispenses the finest web strands — not randomly, but with a specific type of design that can trap other small bugs. It can immobilize its prey and appropriately consume it. It metabolizes its food to generate sufficient energy for mobility, web production, and sensory processing. And it can presumably reproduce itself multifold (although my forbearance with its existence in my house may not extend to cover this circumstance!)
An Advancing Discipline
Even though micro-robotics is an advancing discipline, all the efforts of specialists in this field have not come close to manufacturing anything with the capabilities of this one little spider. The smallest spiders discovered on Earth measure only about 0.4 mm across, perhaps five times smaller than my little window dweller. Packing the many sophisticated capabilities of a spider into such a miniscule package speaks of the highest level of engineering design.
Notes
Vineeth Kumar Bandari and Oliver G. Schmidt, “System-Engineered Miniaturized Robots: From Structure to Intelligence,” Adv. Intell. Syst. 2021, 3, 2000284.
Vineeth Kumar Bandari and Oliver G. Schmidt, “System-Engineered Miniaturized Robots: From Structure to Intelligence,” Adv. Intell. Syst. 2021, 3, 2000284.
Vineeth Kumar Bandari and Oliver G. Schmidt, “System-Engineered Miniaturized Robots: From Structure to Intelligence,” Adv. Intell. Syst. 2021, 3, 2000284.
