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The lack of intuitive and active human-robot interaction makes it difficult to use upper-limb-assistive devices. In this paper, we propose a novel learning-based controller that intuitively uses onset motion to predict the desired end-point position for an assistive robot. A multi-modal sensing system comprising inertial measurement units (IMUs), electromyographic (EMG) sensors, and mechanomyography (MMG) sensors was implemented. This system was used to acquire kinematic and physiological signals during reaching and placing tasks performed by five healthy subjects. The onset motion data of each motion trial were extracted to input into traditional regression models and deep learning models for training and testing. The models can predict the position of the hand in planar space, which is the reference position for low-level position controllers. The results show that using IMU sensor with the proposed prediction model is sufficient for motion intention detection, which can provide almost the same prediction performance compared with adding EMG or MMG. Additionally, recurrent neural network (RNN)-based models can predict target positions over a short onset time window for reaching motions and are suitable for predicting targets over a longer horizon for placing tasks. This study's detailed analysis can improve the usability of the assistive/rehabilitation robots. Agency for Science, Technology and Research (A*STAR) Published version This work was partially supported by the grant “Intelligent Human–robot interface for upper limb wearable robots” (Award Number SERC1922500046, A*STAR, Singapore).

In this paper, we present the modelling of a hyper-redundant mechanism for assisting fingers in achieving desired configurations. The device is composed of serially linked rotating rigid elements and is actuated by a cable-driven mechanism that can provide both flexion and extension. The modelling is based on the analysis of the static equilibrium configurations that the structure acquires, which are dependent on the design parameters of each segment and on the ratio of the tensions applied on the cables. We show how it is possible to obtain different configurations by properly shaping the geometry of each element. Such a relationship was theoretically investigated and experimentally validated to compare the actual configuration with the one predicted by the model. The prototype was designed so that its static equilibrium configuration approximates the geometry of a finger during flexion-extension. It was observed that the customised structure achieves a configuration more closely resembling the desired one than a non-customised actuator. By adapting the design of each element and properly adjusting the ratio of tensions, one is able to compute the final configuration achieved by the actuator so that it can approximate the desired posture.

Polymeric materials systems developed for actuators and human-machine interfaces suffer from limitations associated with effective force output due to their low mechanical modulus. New material solutions which can provide intrinsic multi-modal responses are needed to reversibly modulate rigidity; to be flexible, stretchable and bendable one moment, and to be rigid, able to bear load and resist deformation at another moment. Thermally modulated phase transition materials are promising for modulation of mechanical properties; however, they have not been explored for electrically driven shape morphing and responsive surfaces which require favourable electrical properties too. Polymers like polyethylene glycol (PEG) allow for low melting point (56 ℃) and high dielectric constant (10), however they are limited by slow crystallization kinetics and large temperature window. We architect an MXene incorporated PEG-water hybrid which allows for both reduction in melting point and rapid heterogeneous nucleation, which in turn increases the crystallization point. Multimodal response is demonstrated via thermal and electrical input, resulting in modulation of 700 times in Young's modulus, 100 times in flexural modulus and 10 times in hardness as well as large actuation strains (~28%) at low electric fields (~0.7 V/µm). They can be printed to create hardness domains, allowing for local and programmable modulation. An all-printed haptic device with an array of 3 × 3 pixels has been demonstrated, capable of independently varying the hardness values for each pixel. Ministry of Education (MOE) Accepted version The authors would like to acknowledge the funding support for this project from Ministry of Education (MOE) Tier 1 grant (MOE2018-T1- 002-179) (Singapore).

Soft exosuits have advantages over their rigid counterparts in terms of portability, transparency and ergonomics. Our previous work has shown that a soft, fabric-based exosuit, actuated by an electric motor and a Bowden cable, reduced the muscular effort of the user when flexing the elbow. This previous exosuit used a gravity compensation algorithm with the assumption that the shoulder was adducted at the trunk. In this investigation, the shoulder elevation angle was incorporated into the gravity compensation control via inertial measurement units (IMUs). We assessed our updated gravity compensation model with four healthy, male subjects (age: $26.2 \pm 1.19$ years) who followed an elbow flexion reference trajectory which reached three amplitudes $(25^{\circ}, 50^{\circ}, 75^{\circ})$ and was repeated at three shoulder angles $(25^{\circ}, 50^{\circ}, 75^{\circ})$. To assess the performance of the exosuit; the smoothness, tracking accuracy and muscle activity were investigated during each motion. We found a reduction of biceps brachii activation (24.3%) in the powered condition compared to the unpowered condition. In addition, there was an improvement in kinematic smoothness (0.83%) and a reduction of tracking accuracy (26.5%) in the powered condition with respect to the unpowered condition. We can conclude that the updated gravity compensation algorithm has increased the number of supported movements by considering the shoulder elevation, which has improved the usability of the device.

The electromagnetic stimulation of nervous tissue has represented an alternative to electrical stimulation since the 1980s. The growing number of potential applications has led to an increasing interest in the development of modeling tools that can help the design of novel electromagnetic stimulators. In this context, the aim of this paper is to provide a versatile calculation framework to investigate the properties of the electric field generated by a plurality of miniature coils, arranged in cuff configuration. Furthermore, the capability of the miniature coils to elicit a neuronal response in specific portions of the (peripheral) nerve will be investigated. Starting from Jefimenko's equations, a model was implemented in MATLAB. It calculates the electromagnetic field induced by coils, with arbitrary shape and spatial orientation, and the activating function around the coils through simple numerical integration. By studying the activating functions, it is possible to determine where the neurons can be excited. The model was validated by comparison with FEM simulations. A dimensional analysis was conducted to compare in terms of shape and depth of the stimulation volumes different coil geometries, regardless of design parameters such as current, number of turns and coil sizes.The dimensionless groups identified according to Buckingham's theorem provide a direct estimate of the stimulation depth reached within the nerve.The calculation tools developed in this paper can be used in the design of coils to quickly compare different geometries and spatial distribution of coils in order to identify the optimal configurations for the specific application addressed by the designer.

In this paper, a smart pill for local drug delivery is presented. The pill is designed to achieve local therapy on gastrointestinal tissue thanks to a novel drug delivery system (DDS). The DDS consists of a miniature electrolytic pump. This microfabricated pump is ideal for medical applications because of its low power consumption, compatibility with small size batteries, integrability on miniaturized systems, and biocompatibility. The actuation principle of the micropump relies on the electrolysis of a water-based solution, which is separated from a drug reservoir by an elastic membrane. The electrolytically produced gases pressurize the electrolytic solution reservoir, causing the deflection of the elastic membrane. Such deflection, in turn, forces the drug out of its reservoir through a nozzle. In order to measure and monitor the membrane displacement, and therefore the volume of drug ejected, a strain gauge sensor has been prepared using a conductive thermoplastic nanocomposite elastomer (CTPE). The sensor is fixed on the deformable membrane. The CTPE shows high sensitivity and allows to customize the resistance of the device to obtain low power consumption. Thus, by measuring the current though the electrolytic cell and monitoring membrane deformation, the volume of the ejected drug can be controlled. [2015-0200]

Humans are favoured to conventional robotics for some tasks in industry due to their increased dexterity and fine motor skills, however, performance of these tasks can result in injury to the user at a cost to both the user and the employer. In this paper we describe a lightweight, upper-limb exosuit intended to assist the user during lifting tasks (up to 10kg) and while operating power tools, which are common activities for industrial workers. The exosuit assists elbow and shoulder flexion for both arms and allows for passive movements in the transverse plane. To achieve the design criteria an underactuated mechanism has been developed, where a single motor is used to assist two degrees of freedom per arm. In the intended application, the hands are generally busy and cannot be used to provide inputs to the robot, therefore, a voice-activated control has been developed that allows the user to give voice commands to operate the exosuit. Experiments were performed on 5 healthy subjects to assess the change in Muscular Activation (MA), inferred through Electromyography (EMG) signals, during three tasks: i) lifting and releasing a load; ii) holding a position and iii) manipulating a tool. The results showed that the exosuit is capable of reducing EMG activity (between 24.6% and 64.6%) and the recognition rate (94.8%) of the voice recognition module was evaluated. This work was partially supported by the "Smart Exosuits for Human Augmentation in Industrial Working Environment" project funded by Parts Precision Technology (S) Pte Ltd (project definition: M4062147).

Wearable robotic devices and exoskeletons, that assist human beings in physically-demanding tasks have the potential to both increase productivity and reduce the risk of musculoskeletal disorders. Soft exoskeletons, known as exosuit, provide improved portability and fit. While many exosuits are populating the market to support light weights, very few are powerful enough to reinforce workers in lifting heavy loads. Adopting the advantages of novel soft-robotic principles, we propose a voice-controlled upper limb exosuit designed to aid its user in lifting up to 10kg per arm. The exosuit uses a wire-driven mechanism to transmit power from a proximally-located actuation stage to the shoulder and elbow. Forces are transmitted to the human body via soft, textile-based components. We evaluate the impact of the device on the muscular effort of a wearer in both a lifting and a holding task. Holding a weight of 14kg with the exosuit results in an average reduction in muscular effort of the biceps brachii and anterior deltoid of 50% and 68%, respectively. Similarly, lifting a weight of 7kg with the exosuit reduces the muscular activity of the same two muscles by 23.4% and 41.2%, respectively.

Smart pills were originally developed for diagnosis; however, they are increasingly being applied to therapy - more specifically drug delivery. In addition to smart drug delivery systems, current research is also looking into localization systems for reaching the target areas, novel locomotion mechanisms and positioning systems. Focusing on the major application fields of such devices, this article reviews smart pills developed for local drug delivery. The review begins with the analysis of the medical needs and socio-economic benefits associated with the use of such devices and moves onto the discussion of the main implemented technological solutions with special attention given to locomotion systems, drug delivery systems and power supply. Finally, desired technical features of a fully autonomous robotic capsule for local drug delivery are defined and future research trends are highlighted.

Systems for delivering robot-mediated rehabilitation therapy are useful tools to support clinicians in providing high-intensity, repetitive, and task-specific treatment, in order to maximize the efficacy of the recovery process, especially for neurologically injured patients. Such systems are typically conceived to constantly work in constrained motion with the human body. This is a quite challenging situation for designers: physical human-robot interaction should be properly exploited and optimized, starting from the definition of adequate functional and technical specifications of the overall system up to the integration of some level of real-time, adaptive behavior of the robot that should feature an effective performance while dealing with uncertainty and complexity associated with physiopathologic conditions of human subjects. A top-down, biomechatronic design approach is consequently required to develop systems for robot-mediated therapy: in-depth modeling of the human agent, that is, the patient, must be the first step that provides basic guidance for subsequently running a typical concurrent, iterative mechatronic design cycle of mechanical, electronic, and multilayered control subsystems of the robotic therapeutic machine. The present chapter has the aim to provide an overview on biomechatronic design criteria of generic systems for robot-mediated rehabilitation therapy focused on both the upper and lower extremities. First, basic guidelines on how to build an appropriate model of the human component instrumental for robot design are briefly discussed. Then, criteria for the identification of functional and technical specifications and the selection of key components of the robotic system as a result of the application of a truly biomechatronic approach are introduced. Finally, two design case studies are presented: (a) the CBM-Motus, a planar robot for upper-limb poststroke rehabilitation, and (b) LENAR, a nonanthropomorphic wearable robot for walking assistance.

Capillary and surface effects at the interface between two media enhance adhesion in wet environments. This phenomenon, called wet adhesion, is exploited in nature by some insects and amphibians to stand or walk over wet substrates. Since surface effects are generally voltage-sensitive, as demonstrated, for example, by electrowetting phenomena, one may expect that the strength of wet adhesion could be adjusted by using electric means. Indeed, in this paper, we show that the liquid-mediated adhesion between a flat and a grooved surface, the latter equipped with interdigitated electrodes deposited beneath it, can be reduced by more than 80 %, when a 90 V DC voltage is applied. The described technique points out the possibility of realizing surfaces with tunable adhesive properties, when in contact with wet substrates, which may be useful for several applications, including the development of propulsion systems for autonomous endoscopic robots and the fabrication of microgrippers for the manipulation of small objects.

Advances introduced by additive manufacturing have significantly improved the ability to tailor scaffold architecture, enhancing the control over microstructural features. This has led to a growing interest in the development of innovative scaffold designs, as testified by the increasing amount of research activities devoted to the understanding of the correlation between topological features of scaffolds and their resulting properties, in order to find architectures capable of optimal trade-off between often conflicting requirements (such as biological and mechanical ones). The main aim of this paper is to provide a review and propose a classification of existing methodologies for scaffold design and optimization in order to address key issues and help in deciphering the complex link between design criteria and resulting scaffold properties.

Robots operating in close contact with humans require actuators capable of accurately and safely modulating the delivered torque. To this aim, rotary series elastic actuators are largely adopted. Torque control is often implemented using a cascade control scheme involving proportional–integral regulators (velocity controller nested in a torque controller) for its simplicity and its potential of ensuring coupled stability. A high-level impedance control loop is also commonly added to regulate the interaction with the external agents. In the present work, conservative passivity conditions are derived when a cascade-controlled series elastic actuator is used to haptically display different models of virtual impedance. In particular, the case of a null impedance, of a pure spring and of series and parallel spring–damper systems (corresponding to standard linear viscoelastic bodies) are analyzed in order to derive design guidelines useful for the selection of the control gains as well as for determining the ranges of renderable virtual impedance.

Invasive interfaces with the Peripheral Nervous System (PNS), which currently rely on electric means for both nerves stimulation and signals recording, are needed in a number of applications, including prosthetics and assistive technologies. Recent studies showed that the quality of the signal-to-noise ratio of the afferent channel might be negatively affected by physiological reactions, including fibrosis. In this paper we propose a novel approach to the development of implantable neural interfaces, where the PNS is excited electromagnetically and in situ, while electrical means are used only for neural signals recording. Electromagnetic (EM) waves, capable of overcoming fibrotic capsules, are generated by microfabricated coils. Stimulation coils and registration electrodes are deposited on the same flexible substrate, also provided with a bio-absorbable coating, which releases anti-fibrotic drugs and neurons-specific functionalized magnetic nanoparticles (NPs). The NPs are intended to improve the capability of local EM waves to elicit membranes depolarization, thus enhancing selectivity. This paper details the concept of the proposed technology and provides a preliminary in silico feasibility study.

Slip sensing is important in robotic dexterous manipulation and in advanced upper limb prosthetics because it provides useful information for conveniently adapting manipulation forces. In this paper the physical phenomena involved in slip occurrence are briefly examined, as well as the physiological bases of the human “sense of slip.” Transduction principles and technological approaches, exploited over the years for reproducing the “artificial sense of slip,” are analyzed, with the final aim of identifying the most relevant open issues, as well as research trends.

This paper presents the design of a surgical positioning system conceived to handle and orient a cannula for Minimally Invasive Spine Surgery (MISS) keeping fixed a remote center of rotation during the orientation procedure. Specifically, many MISS treatments require the use of a transpedicular cannula as a guiding tool for spine fixation or for delivering biomaterials to the vertebral body or to the disc space. We designed a cannula orientation mechanism able to percutaneously guide the insertion towards the intervertebral space based only on the acquisition of a few fluoroscopic images. The insertion orientation, and therefore the regulation of the system joints configuration, can be planned by a software based on two perpendicular C-arm fluoroscopic images and starting from the identification of the insertion point and of the insertion direction drawn on the images by the surgeon. We present the software for the orientation planning and a simple kinematic structure with remote center of motion that allows the positioning and orientation of the guiding cannula. The system was dimensioned so to be compatible with the size of C-arm workspace and to minimally interfere with the surgical procedure and with the work of the medical staff.

We report on a novel slip microsensor that uses a strategy similar to the one employed in hot wire anemometry. The device includes a miniaturized probe kept at constant temperature by a dedicated control. The sensor fires a signal whenever it detects an increase in the convective heat transfer associated with the occurrence of mechanical slip. The sensor is microfabricated by patterning multi-layer electrodes on a flat glass substrate. The operating principle, fabrication procedures, and control strategy for the device are described in detail. A simple experimental setup was used to test the effectiveness of the proposed device. Tests were performed on bars of four commonly used materials with varying thermal properties. Also, the slip speed was varied and its effect on the performance of the sensor was evaluated. The results show that, with careful choice of the operational parameters, slip can be detected with a response time comparable to that of human skin receptors. The performance of the device can be further improved when used in conjunction with a separate pressure sensor and by improving the accuracy of the electrical resistance readings.

Ideally, robots used for motor rehabilitation, in particular, during assessment, should minimally perturb the voluntary movements of a subject. In this paper, we show how a state-of-the-art back-drivable robot, i.e., a robot that can be moved by the user with a low perceived mechanical impedance, when used for assessment can still perturb the voluntary movements of a subject. In particular, we show that, despite its low mechanical impedance, a robot may still not comply with the intrinsic kinematic constraints, which are of neural origin and are adopted by the human brain to solve redundancy in motor tasks. Specifically, the redundant task under consideration is the 2-D pointing task, which is performed by a subject with the sole use of the wrist [3 degree of freedom (DOF) kinematics]. Wrist orientations during pointing tasks are assessed in two different scenarios. In the first experiment, a lightweight handheld device is used, which introduces no loading effect. In the second experiment, similar pointing tasks are performed with the subject interacting with a state-of-the-art robot for wrist rehabilitation. In the first case, intrinsic kinematic constraints arise as 2-D surfaces embedded in the 3-D space of wrist configuration. Such surfaces are typically subject-dependent and reveal personal motor strategies. In the second case, a strong influence of the robot is remarked. In particular, 2-D surfaces still arise but are similar for all subjects and are referable to a mechanical origin (excessive loading by the robot). The assessment approach described in this paper, including both the experimental apparatus and data-analysis method, can be used as a test for the degree of back-drivability of mechanisms and robots in relation to constraints of neural origin, thus allowing the design of robots that can actually cope with such constraints. The clinical potential impact is also discussed.

Robots for space applications require a level of autonomy while operating in highly unstructured environments that current control architectures cannot manage successfully. We investigated including pre-developed insect brain tissue into the control architecture of space exploratory vehicles. A doubly hybrid controller is proposed that hinges around the 'insect-in-a-cockpit' concept towards an evolution of the classical deliberative/reactive paradigm, featuring a biological (insect brain) high-level deliberative module coupled with low-level reactive behaviors embedded in a robot. The proposed concept, its design methodology and functional description of the submodules are presented, along with a preliminary feasibility assessment mainly derived from an in-depth review of the state of the art.

The rapid and precise delivery of small volumes of bio-fluids (from picoliters to nanoliters) is a key feature of modern bioanalytical assays. Commercial ink-jet printers are low-cost systems which enable the dispensing of tiny droplets at a rate which may exceed 10 4 Hz per nozzle. Currently, the main ejection technologies are piezoelectric and bubble-jet. We adapted two commercial printers, respectively a piezoelectric and a bubble-jet one, for the deposition of immunoglobulins into an ELISA plate. The objective was to perform a comparative evaluation of the two classes of ink-jet technologies in terms of required hardware modifications and possible damage on the dispensed molecules. The hardware of the two printers was modified to dispense an enzyme conjugate solution, containing polyclonal rabbit anti-human IgG labelled with HRP in 7 wells of an ELISA plate. Moreover, the ELISA assay was used to assess the functional activity of the biomolecules after ejection. ELISA is a common and well-assessed technique to detect the presence of particular antigens or antibodies in a sample. We employed an ELISA diagnostic kit for the qualitative screening of anti-ENA antibodies to verify the ability of the dispensed immunoglobulins to bind the primary antibodies in the wells. Experimental tests showed that the dispensing of immunoglobulins using the piezoelectric printer does not cause any detectable difference on the outcome of the ELISA test if compared to manual dispensing using micropipettes. On the contrary, the thermal printhead was not able to reliably dispense the bio-fluid, which may mean that a surfactant is required to modify the wetting properties of the liquid.

In this paper we present a miniature electrolytic pump sensorized with a novel strain sensor to be used as active component of a drug delivery system. It consists of an electrolytic solution reservoir where inert electrodes are immersed. By polarizing the electrodes, the electrolytic reaction is activated and the produced gases (i.e. oxygen and hydrogen) displace an elastic membrane delimiting the electrolytic solution reservoir. In order to measure and monitor the membrane displacement, and therefore the volume of drug ejected, a strain gauge sensor has been prepared using a conductive thermoplastic nanocomposite elastomer (CTPE). The sensor has been fixed on the deformable membrane. The conductive thermoplastic elastomer is a good candidate for this application because of its high sensitivity. Furthermore, the CTPE allows to customize the resistance of the device in order to obtain low power consumption.

Underactuated compliant swimming robots are characterized by a simple mechanical structure, capable to mimic the body undulation of many fish species. One of the design issue for these robots is the generation and control of best performing swimming gaits. In this paper we propose a new controller, based on AFO oscillators, to address this issue. After analyzing the effects of the motion on the robot natural frequencies, we show that the closed loop system is able to generate self-sustained oscillations, at a characteristic frequency, while maximizing swimming velocity.

No-moving-part (NMP) valves are microconduits able to partially rectify an oscillating fluid moving through them. The modeling of such valves is not at all trivial. Even greater difficulties arise when the behavior of the whole micropump equipped with those NMP valves is investigated, because of the complex fluid-dynamic phenomena interacting with deformable structures. This paper proposes a generalization of the efficiency modeling, nowadays used for single valves, to whole micropump equipped with them. Such modeling has been applied to design a novel, high efficiency NMP valve to be used in a piezoelectric micropump. The main feature of the new valve is the presence of some properly shaped vortex area along its fluid-dynamic pattern, allowing to improve micropump performance. For comparison purposes, the same modeling has been applied to a standard nozzle-diffuser NMP valve to be used with the same piezoelectric actuator. The experimental comparison of micropump performance (maximum flow rate and pressure head) shows that the proposed modeling technique is able to discriminate between better and worse performer. The effects of unsteady dynamic effects have been evaluated a posteriori, confirming their important weight on the actual performance of the micropumps equipped with NMP valves.

In this paper we present a model for calculating the electric field, and its spatial derivatives, produced by arbitrarily shaped, oriented and placed coils carrying time-varying currents. The model has been validated by comparing its results with those obtained using FEM simulations. The model provides a simple and fast computation framework to investigate the electromagnetic stimulation of neural tissues. Some example applications are also provided.

In this paper a novel system for local drug delivery is described. The actuation principle of the micropump used for drug delivery relies on the electrolysis of a water-based solution, which is separated from a drug reservoir by an elastic membrane. The electrolytically produced gases pressurize the electrolytic solution reservoir, causing the deflection of the elastic membrane. Such deflection, in turn, forces the drug out of its reservoir through a nozzle. The proposed system is integrated in a swallowable capsule, equipped with an impedance sensor useful to acquire information on the physiological conditions of the tissue. Such information can be used to control pump activation.

Mozzarella cheese is one of the most counterfeited dairy product worldwide, with implications concerning either economical and health issues. In the context of food quality monitoring and authentication, a non-destructive multi-sensorial analytic approach is proposed. A minimally invasive evaluation of the mechanical properties of the mozzarella cheese as well as of its preserving whey has been performed by means of a mechanical and a liquid sensor, respectively. Data fusion of both approaches allowed a good and easy discrimination between mozzarella cheese samples having different brand provenance and milk composition.

The paper presents the development of segmented artificial crawlers endowed with passive hook-shaped frictional microstructures. The goal is to find design rules for fabricating biomimetic, adaptable and mobile machines mimicking segmented animals with hydrostatic skeleton, and intended to move effectively along unstructured substrates. The paper describes the mechanical model, the design and the fabrication of a SMA-actuated segmented microrobot, whose locomotion is inspired by the peristaltic motion of Annelids, and in particular of earthworms (Lumbricus Terrestris). Experimental locomotion performance are compared with theoretical performance predicted by a purposely developed friction model -taking into account design parameters such as number of segments, body mass, special friction enhancement appendixes--and with locomotion performance of real earthworms as presented in literature. Experiments indicate that the maximum speed of the crawler prototype is 2.5 mm/s, and that 3-segment crawlers have almost the same velocity as earthworms having the same weight (and about 330% their length), whereas 4-segment crawlers have the same velocity, expressed as body lengths/s, as earthworms with the same mass (and about 270% their length).

Novel applications in rehabilitation, surgery and tissue engineering require the knowledge of the mechanical behaviour of the tissues at microstructural level. The aim of this work is to investigate the viscoelastic properties of the tendon from the interaction of its biological constituents in the fibrillar network. Traction, relaxation and creep in-vitro tests have been performed on porcine flexor digital tendons. A viscoelastic constitutive equation at finite deformation is presented. The fibrillar deformation modes are described through a network of adaptive links between collagen type I and decorin. The theoretical predictions fit accurately the experimental data. The results of the model demonstrate the mechanical importance of glycosaminoglycan chains of decorin for the differential recruitment and the activation of fibrillar collagen.

This paper describes a proportional minivalve actuated by shape memory alloy (SMA) actuators and designed primarily for application in semi-autonomous devices for endoscopy (colonoscopy, in particular). As compared to existing valves, the new minivalve exhibits favourable values of working pressure range (0–200 kPa), size, weight and response time. The mechanical structure and the fine proportional control of the minivalve are illustrated. Some innovative features which improve the overall performance of the minivalve (e.g. a waste conduit which increases thermal exchange) are analysed. Fluidic and thermal simulations of the minivalve are presented. Prototypes have been fabricated and tested. Experimental results compare favourably with the performance predicted by the theoretical model. A minivalve has been incorporated in a prototype miniature robot for colonoscopy and preliminarily used to control the locomotion parameters of the robot.

Fiber Bragg Grating (FBG) technology is very attractive to develop sensors for the measurement of thermal and mechanical parameters in biological applications, particularly in presence of electromagnetic interferences. This work presents the design, working principle and experimental characterization of a force sensor based on two FBGs, with the feature of being compatible with Magnetic Resonance. Two prototypes based on different designs are considered and characterized: 1) the fiber with the FBGs is encapsulated in a polydimethylsiloxane (PDMS) sheet; 2) the fiber with the FBGs is free without the employment of any polymeric layer. Results show that the prototype which adopts the polymeric sheet has a wider range of measurement (4200 mN vs 250 mN) and good linearity; although it has lower sensitivity (≈0.1 nm-N1 vs 7 nm-N1). The sensor without polymeric layer is also characterized by employing a differential configuration which allows neglecting the influence of temperature. This solution improves the linearity of the sensor, on the other hand the sensitivity decreases. The resulting good metrological properties of the prototypes here tested make them attractive for the intended application and in general for force measurement during biomedical applications in presence of electromagnetic interferences. © 2014 IEEE.

An innovative approach based on a potentiometric sensor has been employed for peppers characterization. Despite a great number of hot pepper varieties are cultivated worldwide and are consumed, a simple method to discriminate them does not exist yet. A multidimensional system centered on a liquid sensor was used to successfully characterize five different pepper species by means of an easy and rapid procedure. The information deriving from cyclic voltammetry analyses was acquired by the electronic system and further evaluated through a multivariate data analysis approach. The calculated models showed an efficiency of 100 % in the classification of the hot peppers and were able to predict with good accuracy the antioxidant content of the pepper exemplars.

Wearable robots should be designed not to alter human physiological motion. Perturbations introduced by a robot can be quantified by measuring EMG activity. This paper presents tests on the LENAR, an intrinsically back-drivable non-anthropomorphic lower limb wearable robot designed to provide hip and knee flexion/extension assistance. In previous works the robot was demonstrated to exhibit low mechanical impedance and to introduce minor alterations to human kinematic patterns during walking. In this paper muscular activity is assessed, demonstrating small alterations in the EMG patterns during the interaction with the robot, in both unpowered and assistive mode.

Impaired gait can be restored to its physiological level using wearable robotic systems acting alongside human lower limbs and providing assistive forces that adapt to the residual sensory-motor capabilities of the wearer. Such systems can be used as assistive aids (to overcome disabilities or age-related impairments) or as rehabilitation tools (to restore physical and neurological abilities through proper training). In order to elicit physiological gait as a behavior emerging from the interaction between the robot and the user, the robot morphology must be considered as an open design variable, thus relaxing the constraint of using basically anthropomorphic architectures. This chapter deals with several design aspects related to this approach for the development of lower limbs wearable robots. In particular, it analyzes kinematic compatibility issues, possible topological connections among robotic elements, morphological optimization of robot properties, actuation solutions with series compliance, interaction control schemes and user’s intention detection strategies. Pilot tests on a novel non-anthropomorphic device, developed according to the proposed approach, are presented as a case-study, exemplifying the main design aspects described within the chapter.

Scaffolds play a pivotal role in tissue engineering, promoting the synthesis of neo extra-cellular matrix (ECM), and providing temporary mechanical support for the cells during tissue regeneration. Advances introduced by additive manufacturing techniques have significantly improved the ability to regulate scaffold architecture, enhancing the control over scaffold shape and porosity. Thus, considerable research efforts have been devoted to the fabrication of 3D porous scaffolds with optimized micro-architectural features. This chapter gives an overview of the methods for the design of additively manufactured scaffolds and their applicability in tissue engineering (TE). Along with a survey of the state of the art, the Authors will also present a recently developed method, called Load-Adaptive Scaffold Architecturing (LASA), which returns scaffold architectures optimized for given applied mechanical loads systems, once the specific stress distribution is evaluated through Finite Element Analysis (FEA).

We start with a definition of robot in order to understand which are legitimate robotics' objectives. Then it is provided an outline of new robot generations and their industrial and biomedical applications. We consider the consequences of this new kind of technology on the notion of intelligence, stressing how the exteroceptive sensor systems provide a new bottom up approach to the AI debate. We consider three challenges Robotics have to face nowadays. First materials and components, which are built with technologies top-down, set huge limits in terms of weight, speed, safety and cost, not to mention reliability and durability. Second the methodological aspects: the challenge concerns the management of complexity. How to achieve intelligent and adaptive behaviours out of the control system of the robot, which must remain intrinsically simple? A third issue we address is the cultural one: the unreasonable expectations of the general public often provoked by a misunderstanding of the notion of intelligence itself. We consider then what makes human specifically human from a broader philosophic point of view, pointing out how the will is strangely absent in the AI debate. We show three advantages connected with this different perspective instead of the classical one intellect centered. First, while intellect is not used only by man, will is. Second, desire involves intellect while the reciprocal is not necessarily true. Third, looking at robotics and more specifically to cybernetics the key concept of these fields are control and governance, whereas both of them are specifically relate to the domain of will rather than intellect. We look then into the concept of participation as essential to the understanding of the notion of will, to overcome some roboethics' issues related to the adoption of the still dominant rationalistic paradigm.

Fiber optic-based mechanical sensors, thanks to their reduced sensitivity to external electromagnetic fields, are promising in the development of biomechatronic systems able to work in demanding environments, such as MRI chambers. In this chapter we report on the working principle, design, and experimental characterization of a micro-opto-mechanical displacement sensor, which exploits the light modulation induced by the relative displacement of two overlapped micro-fabricated gratings. The gratings are obtained by photo patterning a Pt layer (45 nm thick), sputtered on a Pyrex substrate, into an array of stripes, 150 μm wide and with a 525 μm period. The calibration was carried out up to 525 μm displacement. The sensor showed high and constant sensitivity in the ranges from 30 to 140 μm and from 360 to 490 μm. The experimental data, together with the known advantages of fiber optic-based sensors, encourage further studies for the development of sensors exploiting the proposed measurement principle.

By implanting electrodes inside peripheral nerves, amputee's intentions are picked up and exploited to control novel dexterous sensorized hand prostheses. Under the pretext of presenting surgical technique and clinical outcomes of the implant of invasive peripheral neural interfaces in a human amputee, this article critically comments, from the point of view of the surgeon, strengths and weaknesses of the procedure.Four multielectrodes were implanted in the medial and ulnar nerves of a young volunteer, which, following a car-crash, had a left transradial amputation. Both nerves were approached with a single incision in the medial aspect of the upper arm. Four weeks later, the electrodes were removed.Even if the trauma and the postamputation plastic processes altered the anatomy, electrodes were proficiently implanted with an overall success of 66%. Looking at the procedure from the surgeon's viewpoint unveils few still open issues. Electrodes weaknesses were related to the absence of stabilizing structures, the cable transit through the skin, the implant angle, and the unproven magnetic resonance imaging compatibility. Future investigations are needed to definitely address the better anesthesia, number and sites of incisions, the nerves to implant, and the convenience of performing epineural microdissection.Invasive neural interfaces developmental process almost completely relies on the efforts of bioengineers and neurophysiologists; however, the surgeon is responsible for intra and perioperative factors. Therefore, he deserves to play a major role also at the stage of specifying the requirements, to satisfy the requisites of a safe, stable, and long-lasting implant.

This paper presents tests on a treadmill-based non-anthropomorphic wearable robot assisting hip and knee flexion/extension movements using compliant actuation. Validation experiments were performed on the actuators and on the robot, with specific focus on the evaluation of intrinsic backdrivability and of assistance capability. Tests on a young healthy subject were conducted. In the case of robot completely unpowered, maximum backdriving torques were found to be in the order of 10 Nm due to the robot design features (reduced swinging masses; low intrinsic mechanical impedance and high-efficiency reduction gears for the actuators). Assistance tests demonstrated that the robot can deliver torques attracting the subject towards a predicted kinematic status.

A micro opto-mechanical displacement sensor is here presented. It is constituted by a sensing element based on two overlapped micro-diffraction gratings (MDGs). They present a platinum layer (45 nm of thick) on a glass substrate, a period of 525 μm constituted by a width of 150 μm of platinum separated (71.4% duty cycle). The working principle is based on the modulation of light intensity induced by the relative displacement between the MDGs: when a laser light perpendicularly hits the MDGs, the intensity of the transmitted light is a periodic function of the relative displacement between the two MDGs. A fiber optic is used to transport the transmitted light to a photodetector in order to avoid concerns related to the alignment between the optical components. The sensor's output is the ratio between the light intensity measured by the photodetector during the displacement of the MDGs and largest light intensity values measured in the whole range of measurement, therefore, it is lower than 1. The proposed sensor allows to discriminate displacement lower than 10 μm, using a cost effective micro-fabrication process implemented by the technique of Lift-Off. It shows a good linear behaviour in two ranges covering about one half of the MDGs period. Within the linear ranges it shows high sensitivity (about 0.5%/μm) and good accuracy (lower than 4 % in the whole range of calibration); furthermore, the results show that a design with a duty cycle of 50 % overcomes the marked decrease of sensitivity in a range of measurement corresponding to a grating period.

The introduction of intrinsic compliance in the actuation system of assistive robots improves safety and dynamical adaptability. Furthermore, in the case of wearable robots for gait assistance, the exploitation of conservative compliant elements as energy buffers can mimic the intrinsic dynamical properties of legs during locomotion. However, commercially available compliant components do not generally allow to meet the desired requirements in terms of admissible peak load, as typically required by gait assistance, while guaranteeing low stiffness and a compact and lightweight design. This paper presents a novel compact monolithic torsional spring to be used as the basic component of a modular compliant system for series elastic actuators. The spring, whose design was refined through an iterative FEA-based optimization process, has an external diameter of 85 mm, a thickness of 3 mm and a weight of 61.5 g. The spring, characterized using a custom dynamometric test bed, shows a linear torque versus angle characteristic. The compliant element has a stiffness of 98 N·m/rad and it is capable of withstanding a maximum torque of 7.68 N·m. A good agreement between simulated and experimental data were observed, with a maximum resultant error of 6%. By arranging a number of identical springs in series or in parallel, it is possible to render different torque versus angle characteristics, in order to match the specific applications requirements.

This paper describes the optimization of a planar wearable active orthosis for hip and knee assistance during overground walking. A non-anthropomorphic design is pursued in order to improve ergonomics and to reduce torque requirements. Based on a previously-developed systematic search algorithm of the admissible generalized solutions for the selected problem, a solution is selected and optimized by means of genetic algorithms and constrained non-linear optimization. The optimized design allows to conveniently redistribute mechanical power through different actuators, i.e. peak torque and velocity requirements for each actuator can be modulated, thus promoting a lighter design. A detailed analysis of the resulting mechanism workspace is carried out, including the evaluation of kinematic singularities, in order to verify the adequateness of the design in real-world scenarios. The developed model and optimization results are validated through a numerical analysis and experiments in a mock-up system.

Slip sensors are useful in robotics and prosthetics to improve the precision of force control during manipulation tasks. This work describes the design and fabrication of a flexible slip microsensor with no-moving parts, based on thermo-electrical phenomena. The sensor has been tested on a purposively developed test bench capable of producing a repeatable and controllable slip velocity. Experimental results are reported, demonstrating microsensor capability of discriminating slip events. The flexibility of the sensor makes it suitable for its integration on curved or deformable surfaces, such as robotic finger pads.

Computer-aided tissue engineering comprises a set of methodologies for the fabrication of prosthetic implants by means of rapid prototyping technologies. The paper presents a technique for the preparation of bioactive implants intended to be used in combination with mesenchymal stem cells for the regeneration of bone tissue. The methodology uses additive manufacturing of scaffolds according to a topological optimization algorithm and combines it with chemical functionalization protocols to increase material bioactivity.

In wearable robotics applications, actuators are required to satisfy strict constraints in terms of safety and controllability. The introduction of intrinsic compliance can help to meet both these requirements. However, the high torque and power necessary for robotic systems for gait assistance requires the use of custom elements, able to guarantee high performances with a compact and lightweight design. This paper presents a rotary Series Elastic Actuator (SEA), suitable to be used in an active orthosis for knee assistance during overground walking. The system includes a commercial flat brushless DC motor, a Harmonic Drive gear and a custom-designed torsion spring. Spring design has been optimized by means of an iterative FEM simulations-based process and can be directly connected to the output shaft, thus guaranteeing high torque fidelity. With a total weight of 1.8 kg, it is possible to directly include the actuator in the frame of a wearable orthosis for knee flexion/extension assistance. The presented design allows to obtain a large-force bandwidth of 5 Hz and to regulate output impedance in a range compatible to locomotion assistance of elderly subjects with an age-related decay of motor performances.

While the progress in imaging techniques more and more allows early and accurate diagnosis, minimally invasive intervention is still largely dependent on the availability of smart tools able to perform tasks inside the human body with a high level of autonomy. In this framework, endoscopic robots locomotion capabilities are needed to reach the site of interest, possibly with the desired orientation and with a firm grasping of the tissue. Current locomotion techniques do not provide sufficient degrees of mobility or are hardly miniaturizeable to the desired extent. In this paper we present the concept of a novel locomotion technique, called pinch locomotion, that relies upon and takes advantage of the large deformability of intestine to allow propulsion, steering and standing at a place with a continuous grasping of the tissue. The proposed locomotion technique is instantiated in a preliminary larger-scale prototype (70 mm×29 mm×10 mm), that is able to easily propel itself over a flexible stripe of cloth. The feasibility of a miniature endoscopic robot, endowed with the pinch-locomotion and with dimensions compatible to current swallable devices, is also investigated from a design perspective.

This paper describes the development of an autonomous robotic fish, meant to be used as an experimental platform for the validation of bio-inspired control architectures and sensory-motor coordination models. In its development, particular attention has been paid to the system architecture and the bio-mechatronic design in order to enable 3D swimming patterns, which can be planned taking into account the information flow generated by a rich sensory system. Also, attention has been paid to implement a versatile software architecture. Preliminary results about bio-inspired motion patterns generation and coordination are presented. This work lays the foundations for the development of bio-inspired underwater robots capable of complex behaviors, as required in search-and-rescue applications, as well as in exploration tasks.

In complex dynamical tasks human motor control notably exploits the possibility of regulating joints mechanical impedance, both for stability and for energetic optimization purposes. These biomechanical findings should translate in design requirements for wearable robotics joints, which are required to produce adaptable intrinsic viscoelastic behaviors.