5 Minute Healthtech Jargon Buster: Exoskeletons and Bionics

Exoskeletons [1] are external frames designed to assist and augment human movement. Typically employed in rehabilitation and industrial settings, these devices reduce physical strain and support mobility. They are generally categorised into two primary types:

• passive exoskeletons, which rely on materials like springs and dampers to redistribute loads and minimise muscle strain

• powered exoskeletons, which are equipped with actuators, whether electric, pneumatic, or hydraulic, coupled with sophisticated control systems to actively enhance strength and mobility.

In contrast, bionic devices integrate prosthetics with neurotechnology, specifically through brain-computer interfaces (BCIs), to either replace or augment lost functions. Unlike conventional sensors that simply capture raw data, these devices employ smart sensors and neural interfaces to translate muscle or brain signals into controlled movements, offering transformative potential in healthcare for individuals with mobility impairments, amputations, or neurological disorders.

Modern exoskeletons and bionic limbs rely on advanced materials and engineering techniques to be strong, lightweight, and biomechanically compatible. Key technologies include:

• Lightweight Alloys & Composites: Aerospace-grade aluminium, titanium, and carbon-fibre composites have revolutionised the design of exoskeleton frames. For instance, replacing a traditional aluminium frame with carbon fibre can reduce weight by over 50% while increasing stiffness - German Bionics’ Cray X suit uses a carbon-fibre plastic support that weighs half as much as its aluminium predecessor [2].

• Soft Robotics and Wearable Exosuits: A shift from rigid, bulky exoskeletons to soft, flexible "exosuits," which utilise textiles, elastomers, and compliant actuators like springs or pneumatic muscles, has improved ergonomics and user acceptance. As one leading ergonomics researcher noted, “the future of exoskeletons is soft”[3]. For example, Harvard’s textile ankle exosuit has helped stroke survivors walk faster and further by providing adaptive assistance [4].

• Bio-Integrated Materials: Bionic devices increasingly incorporate bio-integrated materials that interface directly with the human body. Biocompatible implants, such as titanium used for integration with bone in prosthetic limbs, anchor devices directly to the skeleton, providing stable, natural force transmission. Bone-anchored prosthetic legs have demonstrated improved mobility and are becoming a growing clinical option [5]. Researchers are also developing skin-like silicone liners, gel pads, and smart textiles to cushion the contact between device and body, while flexible electronic materials (e.g., electrode arrays or conductive polymers) provide sensory feedback essential for next-generation prosthetics.

• Advanced Actuators & Power Sources: Exoskeletons employ actuators, ranging from miniaturised electric motors to hydraulic or pneumatic systems, to move joints or provide lifting support. Innovations such as regenerative braking, energy-storing springs, and shape-memory alloys allow these devices to mimic natural muscle function while extending battery life through efficient energy use.

Artificial intelligence (AI) plays a pivotal role in bringing exoskeletons and bionic limbs to life, making them not just powered frameworks but intelligent assistants that adapt to user needs. Advanced AI algorithms, including machine learning and adaptive control techniques, are being embedded to improve everything from motion control to the user experience.

• Adaptive Movement and Balance:

  AI enables wearable robots to dynamically tailor assistance to an individual’s biomechanics and current activity [6]. For instance, Lockheed Martin’s Onyx exoskeleton processes inputs from sensors at the foot, knee, and hip to infer the user’s intent, adjusting torque for different terrains. DARPA’s SuperFlex exosuit demonstrated predictive algorithms that precisely timed power delivery [7], leading to smoother, more natural steps and reduced joint strain. These adaptive features promote balance and user safety, ensuring the exoskeleton supplements rather than overrides personal movement preferences.

• Personalised Assistance:

  A groundbreaking Stanford study showcased how an AI-driven ankle exoskeleton can automatically calibrate in minutes using real-time gait and metabolic data [8]. This swift personalisation boosted walking speed by 9% and trimmed energy cost by 17%, effectively mimicking the removal of a 20-pound backpack [9]. By continuously interpreting user metrics, the system demonstrates how AI-driven wearables can streamline mobility support and reduce fatigue, even outside clinical settings.

• Enhanced Prosthetic Control:

  AI drastically advances bionic prostheses beyond traditional myoelectric models that rely on patterned muscle contractions. Pattern recognition and neural networks interpret even faint signals [10], allowing a prosthetic hand to differentiate between subtle intentions like pinching, gripping, or rotating an object. This intelligent approach reduces user training time, providing a more natural extension of the wearer’s body. AI-powered prosthetics thus grant users finer motor control, enabling tasks previously considered too delicate or intricate to perform.

Exoskeletons and bionic technologies are increasingly central to healthcare innovations, playing integral roles in rehabilitation programs, supporting elder care, and serving as powerful assistive tools for individuals with disabilities. Their versatility makes them relevant across a wide spectrum of clinical and everyday scenarios.

• Rehabilitation and Mobility Recovery

  One of the most impactful uses of robotic exoskeletons is in rehabilitation for patients recovering from strokes, spinal cord injuries, or neurological disorders. These devices guide repetitive, precise limb movements, helping rebuild neural pathways essential to regaining mobility. Cyberdyne’s Hybrid Assistive Limb (HAL) detects faint bio-electrical signals in the user’s muscles [11], allowing them to initiate therapy by simply intending to move. Clinical studies with commercially-available exoskeletons report enhanced lower limb strength, increased walking speed, and better overall motor function [12], while spinal cord injury users note improved circulation and reduced muscle atrophy. This approach is not limited to lower limbs; specialised arm exoskeletons can help stroke survivors regain upper-limb dexterity and strength through repetitive, targeted exercise.

• Elderly Care and Mobility Support

  With global populations ageing, exoskeletons can significantly bolster the independence of older adults. By offloading strain on muscles and joints, they reduce the risk of falls and injuries while enabling safer performance of daily tasks. In Japan, power-assist suits help carers and seniors lift heavy objects without incurring back strain [13].

  
  

  Devices like the Muscle Suit Every [14] support the lumbar region, subtracting a substantial portion of the load involved in bending or lifting. Powered braces can also assist weak hips or knees, extending walking ranges and preserving energy. Meanwhile, simplified HAL lumbar exoskeletons in nursing homes [15] aid older adults in sitting, standing, and gait training, supporting both safety and confidence.

• Assistive Technology for Disabilities

  Exoskeletons and bionic prosthetics also offer transformative benefits for people with permanent disabilities. Individuals with paralysis can use devices like ReWalk, Indego, or Ekso, many of which are approved for personal use [16], to stand upright and walk with robotic assistance. These systems provide psychological uplift, improved cardiovascular health, and greater social interaction at eye level. Although current exoskeletons may not match natural walking speeds, they enable achievements such as crossing a finish line in a race or walking short distances unaided—an enormous leap in autonomy.

  
  

  For amputees, AI-enhanced prosthetic limbs restore key functionalities of arms or legs. Microprocessor-controlled systems like Ottobock’s C-Leg or Össur’s Power Knee modulate joint stiffness in real time, simulating muscle action. Multi-articulated hands, such as the Open Bionics Hero Arm or COAPT, grant fingertip-level control for operations ranging from handling small objects to playing musical instruments. A breakthrough occurred in 2018 when a user took DARPA’s “LUKE” arm home [17] successfully learning piano unsupervised. This milestone underscored how advanced prosthetics can transition from experimental prototypes to everyday aids, expanding users’ capabilities in profound ways.

In the UK, the MHRA regulates exoskeletons and AI-driven bionics as medical devices, emphasising a risk-based and innovation-friendly approach [18] Initiatives such as the AI Airlock sandbox [19] enable early dialogue with developers, easing regulatory burdens while ensuring safety. In Europe, these devices are governed under the EU Medical Device Regulation (MDR 2017/745) [20] which requires rigorous clinical evidence and notified body oversight. Moreover, the EU AI Act [21] classifies AI components as high-risk, imposing additional requirements for transparency, risk management, and continuous monitoring.

In the US, the FDA categorises exoskeletons and advanced prosthetic devices as Class II medical devices [22] and provides several regulatory pathways for market entry, such as the Breakthrough Device program and the Software as a Medical Device (SaMD) guidance, promoting adaptive innovation while managing risk [23].

Brain-Computer Interfaces (BCI) for Direct Neural Control

A major frontier in exoskeletons and prosthetics is direct neural control via brain-computer interfaces (BCIs), bypassing muscle activity to decode movement intent directly from the brain. Implanted BCI systems have already demonstrated remarkable breakthroughs. In one study, scientists implanted electrodes in a paralysed man’s motor cortex and a stimulator on his spinal cord; by decoding his brain signals and stimulating his legs, they enabled him to walk with an assistive harness, effectively bridging his injury with a neural bypass [24]. Another milestone involved a tetraplegic patient using a wireless brain-controlled exoskeleton, allowing him to walk and move his arms solely by thinking [25].  Companies like Neuralink are developing high-bandwidth brain implants that could stream motor commands directly to robotic prostheses or reanimate paralysed limbs [26]. Despite ethical and regulatory hurdles, BCIs represent a fascinating fusion of human intent and cybernetic execution, bringing us closer to fully mind-controlled exoskeletons.

Biohybrid Exoskeletons and Living Muscles

A fascinating field at the intersection of biology and robotics is biohybrid exoskeletons, devices integrating living muscle tissue into robotic structures. Muscle cells have the unique ability to contract efficiently when stimulated, making them an ideal actuator for biohybrid robotics. Recently, researchers in Japan engineered a biohybrid robotic hand powered by cultured human muscle bundles. These lab-grown muscles, arranged into tendon-like strands (termed MuMuTAs), allowed the 18-cm robotic hand to perform complex finger movements and grasp objects naturally [27]. While this remains an early-stage proof-of-concept, the potential exists for full-scale biohybrid exoskeletons that use cultivated muscle fibres instead of electric motors, offering a more adaptive and biomimetic movement system.