The central challenge the researchers set out to solve is a familiar one in the field of ionic electroactive materials. Cellulose is flexible, biocompatible, sustainable, and cheap, which makes it an attractive scaffold for soft machines. But pristine cellulose is a poor ionic conductor and electrochemically sluggish, so devices built from it alone cannot move much or respond quickly. Ionic actuators work by shuttling ions through a polymer membrane under an electric field; when ions pile up asymmetrically near the electrodes, one side of the strip swells while the other contracts, producing bending. The speed and magnitude of that bending depend directly on how fast ions can migrate through the membrane and how many charge carriers are available. Any material strategy that improves ion transport therefore translates almost immediately into better actuation.

The Hangzhou group, led by Fan Wang with first author Linghao Xu, attacked the transport problem with a dual-function additive. They first carboxylated cellulose nanocrystals—introducing negatively charged carboxyl groups onto the surface of the rod-like crystalline particles—to create a CCNC matrix. Into this matrix they blended an ionic liquid, which serves as the reservoir of mobile ions, and then added AMPS at two concentrations, 0.2 and 0.4 percent by weight. The membranes were formed by solution casting, a simple and scalable process in which the mixture is spread into a film and dried. Flexible electrodes made of PEDOT/PSS, a well-known conducting polymer blend, were then coated onto both faces of the membrane to complete the trilayer actuator.

AMPS turned out to do two jobs at once. First, it induces the formation of ordered nanochannels within the cellulose network, creating continuous, aligned pathways along which ions can travel through the membrane. Second, its sulfonic acid groups provide sites for proton hopping, a Grotthuss-type conduction mechanism in which protons relay from one acidic group to the next rather than physically diffusing the whole distance themselves. Together these effects raise the ionic conductivity of the composite substantially, and the actuation results show it. The optimized CCNC-IL-AMPS (0.4) actuator—containing 0.4 weight percent AMPS—delivered the 8.38 millimeter tip displacement at 1.5 volts, a dramatic improvement over the CCNC-IL control device, and it maintained stable bidirectional bending, meaning it could flex back and forth repeatedly in both directions without degrading.

Durability is often the quiet killer of ionic actuators, since repeated ion migration can dry out membranes, deplete the ionic liquid, or delaminate the electrodes. The reported device sustained continuous operation for 120 minutes while retaining its bending performance, a result the authors attribute to the well-anchored ionic liquid within the cellulose nanochannel network and the mechanical reinforcement provided by the nanocrystals themselves. Cellulose nanocrystals are stiff crystalline rods, and their hydrogen-bonded network gives the membrane enough structural integrity to survive thousands of bending cycles while remaining thin and compliant enough to flex dramatically. In effect, the nanocrystals act as both the skeleton and the ion-transport plumbing of the device.

Perhaps the most striking aspect of the work is that the actuator does not only move—it also feels. The same device that bends under voltage can report its own displacement and the forces applied to it, a capability known as self-sensing. When the actuator bends, the strain redistributes ions within the membrane and modulates the ionic distribution at the PEDOT/PSS electrode interfaces, producing a measurable electrical signal that tracks the mechanical state of the strip. The researchers quantified the quality of this feedback with correlation coefficients: R² values of 0.9965 for displacement and 0.9953 for micro-force sensing. Values this close to 1.0 indicate an almost perfectly linear relationship between the electrical signal and the mechanical quantity being measured, which is essential if the sensor output is to be used for closed-loop control without complicated calibration.

Self-sensing actuators are a kind of holy grail in soft robotics because they collapse the traditional separation between muscle and nerve. In a conventional robotic system, actuators move the body and separate sensors tell the controller where it ended up, adding wiring, weight, and latency. A material that is simultaneously its own actuator and its own strain gauge allows a soft robot to know its posture from the same electrodes that drive it, simplifying design and enabling proprioception—the body’s sense of its own position—in machines with no rigid parts at all. The linearity demonstrated here suggests the CCNC-IL-AMPS platform could serve that role directly, with the electrical response serving as a reliable proxy for bending angle or contact force.

To demonstrate real-world utility, the team attached the material to the human body and monitored live physiological activity. The strip successfully tracked wrist flexion, the muscular motion of swallowing, coughing, and even the subtle expansion of breathing. These are demanding tests: swallowing and coughing involve rapid, small-amplitude strains, while respiration produces slow, gentle deformation over long periods. The fact that a single cellulose-based strip could resolve all of them points to both high sensitivity and a wide dynamic range. It also underscores the biocompatibility argument for cellulose in the first place—materials destined for prolonged skin contact or even implantable applications benefit enormously from being derived from renewable, non-toxic feedstocks rather than petrochemical polymers.

The broader context is a rapidly growing effort to build sustainable soft machines. Soft robotics has matured from laboratory curiosities into grippers, wearables, and medical devices, but many leading platforms still rely on elastomers, carbon-based fillers, or engineered nanomaterials such as MXenes that carry environmental and cost burdens. Cellulose nanocrystals, extracted from plant matter through established chemical routes such as TEMPO-mediated oxidation and carboxylation, offer a renewable alternative whose surface chemistry can be tuned to control ion transport, mechanical stiffness, and interfacial adhesion. The Zhejiang work builds on the group’s earlier demonstrations of nanocellulose-based electro-ionic actuators, including devices reinforced with carbon nanotubes and graphene nanoplatelets, but the AMPS strategy is notable because it improves performance through molecular design of the ion pathways rather than by adding conductive nanofillers.

There are, of course, steps between a laboratory demonstration and a commercial soft robot or wearable product. The reported actuation was characterized at 1.5 volts in controlled conditions, and scaling the membrane fabrication to larger areas, integrating the devices with flexible electronics, and validating long-term performance over months rather than hours all remain open engineering challenges. The authors also note that data supporting the study will be made available on reasonable request, and the work was funded by the National Natural Science Foundation of China, the Natural Science Foundation of Zhejiang Province, and related programs. Still, the combination of a 139 percent boost in bending displacement, two hours of stable operation, near-perfect self-sensing linearity, and successful human-motion monitoring makes a compelling case that the humble cellulose nanocrystal—seasoned with a pinch of sulfonic acid—could become a backbone material for soft robots, wearable electronics, and human–machine interfaces that move, sense, and endure.

Subject of Research: A cellulose nanocrystal-based ionic soft actuator with integrated self-sensing for soft robotics and wearable applications

Article Title: Actuation and sensing performances of ionic actuator using carboxylated cellulose nanocrystals reinforced with AMPS

Article References: Xu, L., Zhuang, Y., Peng, Y., Zhong, Z., & Wang, F. (2026). Actuation and sensing performances of ionic actuator using carboxylated cellulose nanocrystals reinforced with AMPS. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13808-3

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13808-3

Keywords: cellulose nanocrystals, ionic actuator, soft robotics, AMPS, ionic liquid, PEDOT/PSS, self-sensing, wearable electronics, ion transport, biocompatibility, sustainable materials, human-machine interfaces

The study, led by Vita Hagelskjær and colleagues from the Parker Institute at Copenhagen University Hospital Bispebjerg-Frederiksberg, the University of Southern Denmark, and VIA University College, evaluated the content and delivery of ABLE 2.0, an eight-week, individualized occupational therapy intervention designed for adults with chronic somatic conditions. The evaluation was conducted alongside a randomized controlled trial in a Danish municipality, with data collected between August 2020 and July 2021. Of 38 clients allocated to the ABLE arm of the trial, 29 completed the program, and the results paint a picture of an intervention that works largely as intended, with goal attainment achieved in 55 of 64 cases—an impressive 86 percent success rate.

ABLE 2.0 is the product of nearly a decade of systematic development within the A Better Everyday research programme, established in 2015 and guided by the United Kingdom Medical Research Council’s framework for developing and evaluating complex interventions. The first version, ABLE 1.0, was developed and feasibility-tested between 2015 and 2018. Feedback from that phase prompted targeted refinements: the mandatory number of sessions was reduced, standardized evaluation of activities of daily living (ADL) ability and collaborative goal setting were emphasized, and recent occupational therapy theory was incorporated to strengthen occupation-centered reasoning. The result was ABLE 2.0, a program structured by the Occupational Therapy Intervention Process Model (OTIPM), which provides a systematic framework for client-centered, occupation-based practice.

The technical architecture of the intervention is worth examining closely because it illustrates how modern rehabilitation science translates theory into practice. In the first session, clients undergo standardized evaluation of both self-reported and observed ADL ability using the ADL Interview (ADL-I) and the Assessment of Motor and Process Skills (AMPS), a validated observational instrument that measures the motor and process skills a person enacts while performing chosen everyday tasks. This session also involves determining any discrepancy between what clients report about their ability and what structured observation reveals. The second session centers on collaborative goal setting using Goal Attainment Scaling (GAS), a measurement approach in which goals are scaled across levels of expected attainment, alongside an analysis of the underlying reasons for task performance problems using the Person-Environment-Occupation model or the Transactional Model of Occupation.

Sessions three through seven then offer an individualized combination of nine intervention components, ranging from changing habits related to task performance and changing attitude, to modifying the physical or social environment, using tools and assistive technology, dividing tasks into smaller steps, and simplifying task processes. The program builds on a compensatory intervention model, applying adaptational strategies—changes to the environment, assistive devices, adjusted routines—rather than attempting to restore impaired performance skills directly. The final session includes re-evaluation of goal attainment. Sessions one, two, and the final session are mandatory, establishing a minimum dose of three contacts, and the program can be delivered face-to-face or by telephone, with homework assigned between sessions in more than 71 percent of cases. Examples of such homework included practicing to vacuum using new body positions, taking out the waste with a walker, and sitting down while dressing.

The process evaluation, structured according to the framework proposed by O’Cathain and colleagues, examined five dimensions: intervention development and components, mechanisms of action, perceived value and unintended consequences, feasibility and acceptability in practice, and fidelity, reach, and dose. Data came from registration forms completed independently by clients and occupational therapists after every session, with clients submitting their forms in sealed envelopes to avoid influence from the treating therapist. All nine intervention components were applied during the study period, with changing habits the most frequently implemented (34 instances), followed by changing attitude (32) and the use of tools, technology, and assistive devices (23). Session duration varied considerably, from a median of 42.5 minutes in session four to 120 minutes in the evaluation-heavy first session, underscoring the individualized nature of the delivery.

Perhaps the most striking findings concern the mechanisms of action. Both clients and therapists reported that the standardized ADL evaluations in the first session provided new insights into the client’s ability, clarified the focus of the intervention, and established a solid foundation for the collaborative relationship. This is notable because data from the parallel effectiveness trial showed that clients receiving usual occupational therapy in the municipality were typically not offered standardized evaluations at all, and their goals were usually set by the referral service rather than negotiated with the client. The 86 percent goal attainment rate in the present study also represents a substantial improvement over the 52 percent achieved in the earlier ABLE 1.0 feasibility study, suggesting that the refinements to the manual and the enhanced training—particularly the emphasis on collaborative goal setting—paid off. Occupational therapists themselves reported feeling skilled to a high or very high degree and found delivering the sessions satisfying, and no side effects were reported at all.

The findings do, however, reveal persistent friction points. A small number of deviations from the manual occurred: the AMPS evaluation was omitted for two clients, and one client expressed no goals, making GAS-based goal setting impossible. Therapists noted challenges with goal setting, and one remarked on doubt about whether a client fully understood the discrepancy dialogue. The authors argue these difficulties reflect limited routine in conducting standardized evaluations and collaborative goal setting within Danish municipal practice—a concern echoed by recent Swedish and Danish studies documenting sparse use of standardized assessment tools in primary healthcare and assistive technology services. Because collaborative goal setting was identified in the companion realist evaluation as a core mechanism of change in ABLE, the researchers recommend further refinement of the manual and training course on this specific aspect before wider implementation.

Retention also emerged as a key consideration for future rollout. Five clients dropped out before the first session, mainly due to hospitalization, and four more left before the second session, citing lack of motivation, bereavement, or no perceived need for intervention. Those who dropped out were slightly younger and had somewhat higher baseline ADL motor ability than completers, hinting that the program may be most beneficial for older adults with lower ADL ability—a conclusion supported by the effectiveness trial, which found clinically relevant and statistically significant improvements in observed ADL motor ability at both ten and twenty-six weeks among ABLE recipients, though no significant changes in self-reported ADL ability. The gap between observed and self-reported outcomes remains an intriguing puzzle for the field, but the observed gains translate into clients performing daily tasks with greater efficiency, less physical effort, and improved safety.

Taken together, the process evaluation confirms that ABLE 2.0 is feasible, acceptable, and deliverable with high fidelity within real-world municipal rehabilitation services. Its essential ingredients—standardized evaluation of ADL ability, collaborative goal setting, identification of the reasons behind task performance problems, and client engagement in trying out adaptational strategies at home—form a coherent, evidence-based template for helping people with chronic conditions reclaim their everyday lives. The authors emphasize that future implementation efforts should prioritize embedding standardized evaluation into clinical routines, optimizing training in collaborative goal setting, and treating recruitment as a central uncertainty. With a cost-effectiveness evaluation still in progress and an implementation strategy on the research agenda, the ABLE programme is steadily building the comprehensive evidence base needed to move from promising trial results to routine clinical practice across Danish municipalities and beyond.

Subject of Research: Feasibility and delivery of a home-based, occupation-centred problem-solving occupational therapy intervention for adults with chronic somatic conditions

Article Title: Content and delivery of occupation-centred problem-solving occupational therapy for people with chronic somatic conditions: A process evaluation of ABLE 2.0

Article References: Hagelskjær, V., Nielsen, K. T., Frilev, T. R., von Bülow, C., & Wæhrens, E. E. (2025). Content and delivery of occupation-centred problem-solving occupational therapy for people with chronic somatic conditions: A process evaluation of ABLE 2.0. Scandinavian Journal of Occupational Therapy, 32(1), 1-16. https://doi.org/10.1080/11038128.2026.2619344

Image Credits: AI Generated

DOI: 10.1080/11038128.2026.2619344

Keywords: occupational therapy, ABLE 2.0, activities of daily living, chronic conditions, process evaluation, goal attainment scaling, AMPS, rehabilitation, home-based intervention, adaptational strategies, municipal health services, Denmark