Developmental Bioengineering

Among the challenges for nature-inspired engineering is how to build synthetic devices capable of emulating the process of development, and its uses in repair and regeneration. Here, I offer a set of principles for designing and building bio-synthetic self-repairing devices based upon nature’s process of development. First, nature’s living devices are built by a process of gene and environment regulated self-organization. I illustrate this principle with the process by which nature builds embryos and discuss how bioengineers are using in vitro organoids to model nature’s process. Second, devices are inseparable from the micro-environments in which they develop, as illustrated in nature by the micro-environment of stem cells, called niches, as well as by the regulatory interactions between stem cell and niche. Bioengineers leverage the mechanical and chemical properties of the niche to build synthetic organs, via processes such as bio-printing. A challenge in emulating the way that nature builds organs is the incorporation of vasculature. Third, nature builds consortia of heterogeneous parts that exhibit distributed control, evident in the relation between neurons and glial cells during development of the mammalian nervous system, and in communication between gut bacteria and the brain. Research has demonstrated that manipulating the properties of the gut microbiome influences the brain and may actually change behavior. This may provide leverage for bioengineers in promoting healthy behavior of individuals with neuropathology. Fourth, nature repairs worn-out or damaged parts by recapitulating the developmental processes used to build them. For example, nature uses progenitor, or stem cells, both during development and to repair injured organs. However, not all animals have the same capability for repair and regeneration, as evident in the contrast between salamanders that can regrow a lost limb, and humans who cannot. Bioengineers facing the challenge of repairing human spinal cord injury have made great strides in promoting regeneration by emulating the process in other animals, such as axolotls. Fifth, nature’s parts and systems may switch from one function to another, depending upon the context of intrinsic regulatory networks and environmental signals. Glial cells, called microglia, are resident central nervous system immune surveillance cells that have multiple functions during development, including synaptic refinement and clearing dead and dying cells. The detection of changes in a cell’s microenvironment may switch microglial function from surveillance to clearance. In diseases such as neurodegeneration, synapses may be incorrectly marked as debris, and activate microglia to eliminate them. It may be possible for bioengineers to program swarms of bio-hybrid molecular robots for similar surveillance functions. Sixth, biological regulatory systems allow animals, such as killifish, to enter altered metabolic states under adverse environmental conditions, such as drought. Synthetic biologists are emulating the processes by which nature enables animals to enter different metabolic states. And seventh, biological systems exhibit emergent properties, such as low-dimensional patterns in the vast connectivity of brain networks as well as in behavior. The appearance of these low dimensional patterns in recordings of animal reaching behavior has implications for control of neuro-prosthetic devices

Design and control of a bio-inspired soft wearable robotic device for ankle-foot rehabilitation

Abstract We describe the design and control of a wearable robotic device powered by pneumatic artificial muscle actuators for use in ankle-foot rehabilitation. The design is inspired by the biological musculoskeletal system of the human foot and lower leg, mimicking the morphology and the functionality of the biological muscle-tendon-ligament structure. A key feature of the device is its soft structure that provides active assistance without restricting natural degrees of freedom at the ankle joint. Four pneumatic artificial muscles assist dorsiflexion and plantarflexion as well as inversion and eversion. The prototype is also equipped with various embedded sensors for gait pattern analysis. For the subject tested, the prototype is capable of generating an ankle range of motion of 27 • (14 • dorsiflexion and 13 • plantarflexion). The controllability of the system is experimentally demonstrated using a linear time-invariant (LTI) controller. The controller is found using an identified LTI model of the system, resulting from the interaction of the soft orthotic device with a human leg, and model-based classical control design techniques. The suitability of the proposed control strategy is demonstrated with several angle-reference following experiments

Développement moteur: La robotique au secours de la psychobiologie du développement

Cet article a pour objectif de susciter une discussion sur les possibles contribution des expriences robotiques la connaissance du dveloppement moteur des jeunes enfants. Plus prcisment, il se focalise sur les points suivants : 1) comment les interactions entre les systmes nerveux, musculaire et osseux et les forces agissant sur le corps, induisent des changements d'organisation du systme densemble, et (2) comment le comportement exploratoire et les signaux d'information slectifs impliqus dans l'apprentissage d'une nouvelle comptence lchelle microgntique, peuvent permettre de stabiliser le comportement lchelle du dveloppement macrogntique. L'article dcrit la dmarche qui a conduit dgager trois principes gnratifs, inspirs de la biologie dveloppementale et se rvlant tre la base de lapprentissage du saut sur Jolly Jumper par de jeunes enfants. Ces principes ont t ensuite dcomposs en un ensemble de mcanismes permettant de contrler un systme robotique, et ont abouti un profil dveloppemental similaire. Une comparaison des performances des enfants et des robots a conduit laborer un ensemble de critres destins amliorer la contribution des tudes robotiques la connaissance du dveloppement moteur

Ontogeny of infant bimanual reaching during the first year. Infant Behavior and Development,

Abstract: Handedness and pattern of coordination during bimanual reaching were assessed separately for six groups of infants, 7 to 12 months old. Infants reached bimanually for a transparent toy-filled box. On some presentations of the box a low barrier was placed in the path of either the right or left hand, while on other presentations there was no barrier. The youngest and two oldest groups of infants were more likely thon the other age groups to perform simultaneous bimanual reaches with no barrier present, but when a barrier was present the 11.montholds were most likely to continue to perform simultaneous reaches. This suggests that while infants as young as 7 months perform simultaneous reaches, the organization of these reaches may be different than for older infants. Hand-use preference contributed significantly to selection of a lead hand in non-simultaneous bimanual reaching. The 8-month group, which had the highest proportion of infants with a hand preference, was the only group likely to hit the barrier when it was placed on the nonpreferred side. Hand preference may, thus, bias the use of information about what the environment affords for action

Active Modular Elastomer Sleeve for Soft Wearable Assistance Robots

Abstract — A proposed adaptive soft orthotic device performs motion sensing and production of assistive forces with a modular, pneumatically-driven, hyper-elastic composite. Wrapping the material around a joint will allow simultaneous motion sensing and active force response through shape and rigidity control. This monolithic elastomer sheet contains a series of miniaturized pneumatically-powered McKibben-type actuators that exert tension and enable adaptive rigidity control. The elastomer is embedded with conductive liquid channels that detect strain and bending deformations induced by the pneumatic actuators. In addition, the proposed system is modular and can be configured for a diverse range of motor tasks, joints, and human subjects. This modular functionality is accomplished with a decentralized network of self-configuring nodes that manage the collection of sensory data and the delivery of actuator feedback commands. This paper mainly describes the design of the soft orthotic device as well as actuator and sensor components. The characterization of the individual sensors, actuators, and the integrated device is also presented. Fig. 1. Overall structure of the modular active elastomer sleeve prototype. I