This article chronicles the rise of a new generation of robots whose boundary-breaking form and domain-transforming function are shaped by the synthesis of organic components and mechanical parts.
Success in meeting the unique challenges of the development of these biomechanical robots and our ability to realise their full potential will depend as much on the invention of new technologies as on the invention of a new vocabulary to describe them.
Introduction
We are living in an age where domains once clearly delineated have been eclipsed by what British botanist Merlin Sheldrake refers to as ecosystems that “span boundaries and transgress categories”. Exemplifying the phenomenon of boundary-spanning “ecosystems” Sheldrake has identified, a new cohort of robots that integrate biological systems with mechanical components is making its debut.
A bio-sensing robot developed by scientists at Carnegie Mellon University and the University of Southern California in the U.S. that integrates organic and inorganic elements to detect chemicals in the environment and a network-aware robot conceived by students on the Paris-based 2022 iGEM Bettencourt team whose interface facilitates communication between colonies of bacteria and the Internet are among the more prominent occupants of the liminal space that Sheldrake has marked out. They also represent the latest phase in the evolution of solutions incorporating bio-based components and mechanical devices.
The History and Evolution
“Biomimetic", "bioinspired" and "bio-based" are just a few terms coined by scientists, philosophers and medical experts to describe how these solutions have evolved to place robotics in closer proximity to the biological systems they interface with. These terms help describe a variety of forms and functions, from a pacemaker overlaid on the heart to regulate its rhythm to prosthetic limbs that approximate the form and function of the appendages they replace.
In as far as they incorporate both biological systems and mechanical devices, the bio-sensing and the network-aware robots are the legitimate heirs of this evolution and well-positioned to extend its trajectory. However, they distinguish themselves from their predecessors in a number of fundamental ways:
The degree to which they integrate bio and mechanical elements - not just straddling the boundary between the two domains, but effectively dissolving it.
The materials they employ - replicating and, in some cases, even replacing commonly used polymer-based components with organic, bio-based parts.
The scope of their application - from an exclusive focus on the human body ( pacemakers, prosthetic limbs, etc.) to broader industrial use.
To achieve these enhancements in design, fabrication, and scope, the scientists behind the development of these robots have leveraged insights gleaned from the latest advances in synthetic biology, a discipline whose practitioners apply engineering principles to redesign biological organisms and soft robotics, a field that has set itself the goal of producing kinder, gentler robots using components made of novel materials that are both sensitive to even the most subtle changes in pressure and pliable enough to respond to those changes.
Building Blocks
Regardless of their function and the focus of their application, technologies such as the bio-sensing and network-aware robots draw on a common set of building blocks: actuators that transform energy into a force capable of moving mechanical devices, sensors that detect changes in the environment and then transmit information about those changes to a receptor that can act on it, transformers that mediate between systems that would be otherwise incompatible.
The use of actuators, sensors and transformers is certainly not exclusive to the bio-sensing and network-aware robots. They are integral parts of virtually all automated control systems. What makes these biomechanical robots unique is not the use of these components, but rather the way in which they use them. The novelty of this application is most readily apparent in their implementation of sensors and transformers.
Both biosensing and network-aware robots eschew traditional sensors made from synthetic materials in favor of organic ones formed from colonies of bacteria specially engineered to emit a chemical signal in a systematic and controllable way when they encounter a change in the environment. “We took our inspiration from the innate ability of bacteria to generate a response to changes in their environment and then we thought about how we could repurpose that as the basis for a signaling scheme,” explained Kyle Justus, PhD student in the Mechanical Engineering Department at Carnegie Mellon University and lead researcher on the bio-sensing robot development team. To facilitate communication between the bacterial sensors and the robots’ electronic systems, the team devised an interface module that makes use of a phototransistor mounted on a printed circuit board. The transistor is capable of recognizing fluorescent signals emitted by proteins the bacteria express when they encounter changes in the environment and then converts those chemical signals into electronic signals that mechanical devices can recognize and respond to.
Challenges
Developing these components and implementing them is one thing, actually getting them to work together is quite another. “Initially, we weren’t able to detect the signal the bacteria generated,” recalled Dr. Cheemeng Tan, a professor in the Biomedical Engineering Department at the University of California/Davis and research adviser on the bio-sensing robot development team, highlighting the type of hurdles those attempting to integrate discrete mechanical components and complex biological systems are likely to encounter. Seen in broader context, these system integration obstacles represent just one of a diverse range of often interdependent challenges that developers of biomechanical robots must contend with.
The bio sensing robot team was eventually able to amplify the signal the bacterial sensor emitted by filtering out the “noise” that was an unintended by-product of the method the scientists used to provoke a response from the bacteria colony. Despite these achievements, there were a number of challenges that remained unresolved, such as growing bacteria stably, particularly in the context of a complex real-world environment. This is not a trivial task given the sensitivity of bacteria to environmental conditions. Ambient temperature, for example, must be strictly maintained within a specific range for optimal results, that is dependent on the species or even strain.
Assuming such a product could be developed, securing regulatory approval to incorporate bacteria in the product design, for example, would be a necessary precondition for production. It will then be necessary to provide all the biosecurity guarantees so that potential users can confidently appropriate this new type of product. It is clear that achieving success in devising solutions effective enough to overcome the challenges and obstacles, scientific and regulatory, will depend on a thorough understanding of the complex interplay between hardware, wetware (hardware’s biological corollary) and software, as well as a strong emphasis on creativity and innovation.
Conclusion: Future View
Despite their number and complexity, the challenges highlighted have not dampened the enthusiasm of the systems engineers, molecular biologists, and designers who have committed themselves to developing these robots. The progress they have made has encouraged them to think more expansively about the future.That future, as they envision it, will be defined by broad-based networks whose dense connections will undergird the integration of biological and mechanical systems and, ultimately, constitute the foundation on which environmentally-friendly applications that don’t sacrifice efficiency or productivity will be built.
It is widely assumed that realizing this vision of the future and exploiting the full potential of the biomechanical systems that shape it will depend on the ability of those working at the intersection of synthetic biology and soft robotics to invent new technologies that push against the boundaries of our current scientific understanding. Yet Sheldrake suggests that it may not be the invention of new technologies that poses the greatest challenge to conceiving these “boundary-spanning” systems, but the invention of a new vocabulary capable of overcoming the limitations of our language to describe them. Even though they are still in a nascent phase of development, the robots featured here are tangible demonstrations of the promise the future for biomechanical solutions holds and give confidence that with necessary refinements to technology and language, challenges that have already been identified and those not yet imagined can be addressed and overcome.
References
Justus, Kyle B., et al. "A biosensing soft robot: Autonomous parsing of chemical signals through integrated organic and inorganic interfaces." Science Robotics 4.31 (2019): eaax0765. DOI: 10.1126/scirobotics.aax0765
Sheldrake, Merlin. Entangled life: How fungi make our worlds, change our minds & shape our futures. Random House Trade Paperbacks, 2021.
iGEM Paris Bettencourt. "Paris Bettencourt 2022." iGEM Wiki, 2022, https://2022.igem.wiki/paris-bettencourt/.
Softbotics." Carnegie Mellon University Engineering, 2024, https://engineering.cmu.edu/softbotics/index.html.
This article was copy edited by Carys Croft
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