Biohybrid robotics combines engineered artificial structures and living bio-systems. The main motivation for biohybrid robots is to provide actuation using bio-hybrid actuators. Biohybrid robots may use bacteria or other motile cells. Actuators have also been based on explanted whole-muscle tissues, cardiomyocytes, optogenetically modified cardiomyocytes, insect self-contractile tissues and engineered skeletal muscle.
Proposed applications for biohybrid actuators include miniaturized therapeutic robots and biohybrid medical devices, in vitro muscle models for drug testing and platforms for investigating muscle contractions. In the longer term biohybrid actuators have applications in the interaction of soft robotic artifacts with humans, microscale devices that perform medical procedures, biobased surveillance systems, manufacturing systems that self-assemble and self-repair and environmental monitoring with swarm biorobots.
Biobots that could be injected into a patient’s bloodstream and destroy a blood clot or cancer would require sensing, computation and actuation. Living cells have an advantage over synthetic microswimmers in their ability to detect and respond to environmental stimuli without additional components. Bacteria and algae can be steered using their attraction to light, which is not possible in deep tissues of the body. Magnetic control is one possibility for medical applications since magnetic fields can safely penetrate the body. Magnetotactic bacteria naturally have magnetic nanocrystals and other living cells could be artificially magnetized if embedded with iron oxide nanoparticles or by attaching them to magnetic substrates. Chemicals can also control cell behavior. Biohybrid devices could respond to biochemical signals released from tumor cells. Thermotaxis and aerotaxis are also possible ways to steer microorganism-based biohybrid robots.
Researchers at Polytechnique Montréal demonstrated magnetic guiding of a magnetotactic bacteria bound to drug-containing nanoliposomes. These Magentococcus marinus bacteria also use aerotaxis, to migrate towards low oxygen in their natural environment. Since tumors are also low oxygen environments, the researchers demonstrated in mice that this aerotaxis can be exploited for delivering drugs to tumors.
Beating cells from a rat (ventricular cardiomyocytes) were first placed on poly(dimethylsiloxane) (PDMS) thin films in 2007 by Whitesides and Parker. This work defined a biohybrid soft robotic device as a hybrid device which has a soft body and where the actuation is performed by a living biological part. Soft biohybrid robots go beyond replication of nature, but seek to fulfill tasks that neither nature nor physical robots can achieve.
Professors Anne Staubitz and Christine Selhuber-Unkel at University of Bremen and University of Kiel proposed a taxonomic scheme for the concept of “living materials” used in biohybrid soft robotics. Their taxonomy builds on the taxonomy scheme put forth by Webster-Wood.
The following are examples of biohybrid soft robots described by the taxonomy scheme. The walker is a biobot actuated by a skeletal muscle ring modified for optogenetic control with light. The pump is a bio-micropump on a chip powered by earthworm muscle.
Researchers at University of Illinois developed soft robotic devices driven by neuromuscular tissue that triggers when stimulated by light using optogenetics, which was published in 2019 in PNAS. In 2014, the team developed self-propelled biohybrid swimming and walking biobots that uses cardiac muscle cells from rats, which beat on their own, as motors. Their swimming biobots were modeled after sperm, with a single tail. In the 2019 version, optogenetic neuron cells, derived from mouse stem cells, were added to their device with two tails. The biobots self assemble since neurons advanced towards the muscle and formed neuromuscular junctions. The resulting neuromuscular tissue worked with their synthetic biobot skeletons. Muscle activity is controlled by neuron activity, which is controlled by exposure to light using optogenetics.
Su Ryon Shin and Ali Khademhosseini are corresponding authors
Harvard Medical School, King Abdulaziz University, Jeddah, Saudi Arabia and Konkuk University, Seoul
An autonomous structure-controlled self-actuating ray powered by cardiomyocytes using design and structuring principles.
Gaszton Vizsnyiczai, Giacomo Frangipane, Claudio Maggi, Filippo Saglimbeni, Silvio Bianchi & Roberto Di Leonardo
NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Rome
"The synthetic components consist of 3D interconnected structures having a rotating unit that can capture individual bacteria into an array of microchambers so that cells contribute maximally to the applied torque. Bacterial cells are smooth swimmers expressing a light-driven proton pump that allows to optically control their swimming speed."
Park, Sung-Jin et al. Corresponding author Kevin Kit Parker.
Harvard University, Sogang University, Stanford University
Swimming robot mimics a ray fish (1/10 scale version) powered by cardiomyocytes genetically engineered to respond to light cues. The robot was built with microfabricated gold skeleton and rubber body.
Caroline Cvetkovic, Ritu Raman, Vincent Chan, Brian J. Williams, Madeline Tolish, Piyush Bajaj, Mahmut Selman Sakar, H. Harry Asada, M. Taher A. Saif, and Rashid Bashir
University of Illinois at Urbana-Champaign, MIT
Yoshitake Akiyama,Takayuki Hoshino,Kikuo Iwabuchi,Keisuke Morishima
Osaka University, Tokyo University of Agriculture and Technology
Yo Tanaka, Kae Sato, Tatsuya Shimizu, Masayuki Yamato, Teruo Okanobd and Takehiko Kitamori
The University of Tokyo, Japan Science and Technology Agency, Kanagawa Academy of Science and Technology (KAST)
Adam W. Feinberg, Alex Feigel, Sergey S. Shevkoplyas, Sean Sheehy, George M. Whitesides*, Kevin Kit Parker*
Cell sheet engineering using rat cardiomyocytes on polydimethylsiloxane thin films was used to build centimeter-scale biohybrid constructs that perform functions as diverse as gripping, pumping, walking, and swimming with fine spatial and temporal control.
Development and Future Challenges of Bio-Syncretic Robots
Living Materials Herald a New Era in Soft Robotics
Clement Appiah, Christine Arndt, Katharina Siemsen, Anne Heitmann, Anne Staubitz, Christine Selhuber-Unkel
July 3, 2019
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- Soft roboticsA field of engineering that designs and builds soft robots. One aim is to improve performance of robots in healthcare applications. Soft robots consist mainly of soft material and may mimic human touch.
- Tissue engineeringTissue Engineering is a multidisciplinary scientific field working on the development of lab grown tissues, such as organs, muscle tissues, or specific cell types, by combining expertise from synthetic biology, molecular biology, biology, chemistry, material science, and mathematics.
- 3D cell culture3D cell culture techniques use engineering to provide 3D environments for cells to grow. Cells can be attached to or embedded in scaffolds engineered from biological or synthetic materials or grown in conditions that promote cells to self-organize into 3D structures.
- Cell cultureProcess by which cells are grown under controlled conditions. Adherent monolayer and free-floating suspension cultures are the two primary growth strategies used for culturing cells.
- Stem cellStem cells are self-renewing cells that have the potential to become multiple different cell types in the body. Stem cells are found in developing embryos. Adult stem cells maintain and repair tissues throughout life. Induced pluripotent stem cells are a type of stem cell derived from adult cells that are reprogrammed in the lab.