A. Benvenuto

Double nerve intraneural interface implant on a human amputee for robotic hand control

OBJECTIVES The principle underlying this project is that, despite nervous reorganization following upper limb amputation, original pathways and CNS relays partially maintain their function and can be exploited for interfacing prostheses. Aim of this study is to evaluate a novel peripheral intraneural multielectrode for multi-movement prosthesis control and for sensory feed-back, while assessing cortical reorganization following the re-acquired stream of data. METHODS Four intrafascicular longitudinal flexible multielectrodes (tf-LIFE4) were implanted in the median and ulnar nerves of an amputee; they reliably recorded output signals for 4 weeks. Artificial intelligence classifiers were used off-line to analyse LIFE signals recorded during three distinct hand movements under voluntary order. RESULTS Real-time control of motor output was achieved for the three actions. When applied off-line artificial intelligence reached >85% real-time correct classification of trials. Moreover, different types of current stimulation were determined to allow reproducible and localized hand/fingers sensations. Cortical organization was observed via TMS in parallel with partial resolution of symptoms due to the phantom-limb syndrome (PLS). CONCLUSIONS tf-LIFE4s recorded output signals in human nerves for 4 weeks, though the efficacy of sensory stimulation decayed after 10 days. Recording from a number of fibres permitted a high percentage of distinct actions to be classified correctly. Reversal of plastic changes and alleviation of PLS represent corollary findings of potential therapeutic benefit. SIGNIFICANCE This study represents a breakthrough in robotic hand use in amputees.

Does an intraneural interface short-term implant for robotic hand control modulate sensorimotor cortical integration? An EEG-TMS co-registration study on a human amputee

PURPOSE Following limb amputation, central and peripheral nervous system relays partially maintain their functions and can be exploited for interfacing prostheses. The aim of this study is to investigate, for the first time by means of an EEG-TMS co-registration study, whether and how direct bidirectional connection between brain and hand prosthesis impacts on sensorimotor cortical topography. METHODS Within an experimental protocol for robotic hand control, a 26 years-old, left-hand amputated male was selected to have implanted four intrafascicular electrodes (tf-LIFEs-4) in the median and ulnar nerves of the stump for 4 weeks. Before tf-LIFE-4s implant (T0) and after the training period, once electrodes have been removed (T1), experimental subjects cortico-cortical excitability, connectivity and plasticity were tested via a neuronavigated EEG-TMS experiment. RESULTS The statistical analysis clearly demonstrated a significant modulation (with t-test p < 0.0001) of EEG activity between 30 and 100 ms post-stimulus for the stimulation of the right hemisphere. When studying individual latencies in that time range, a global amplitude modulation was found in most of the TMS-evoked potentials; particularly, the GEE analysis showed significant differences between T0 and T1 condition at 30 ms (p < 0.0404), 46 ms (p < 0.0001) and 60 ms (p < 0.007) latencies. Finally, also a clear local decrement in N46 amplitude over C4 was evident. No differences between conditions were observed for the stimulation of the left hemisphere. CONCLUSIONS The results of this study confirm the hypothesis that bidirectional neural interface could redirect cortical areas -deprived of their original input/output functions- toward restorative neuroplasticity. This reorganization strongly involves bi-hemispheric networks and intracortical and transcortical modulation of GABAergic inhibition.

Intrafascicular thin-film multichannel electrodes for sensory feedback: Evidences on a human amputee

The performance of motor neuroprostheses or robotic arm prostheses can be significantly improved by delivering sensory feed-back related to the ongoing motor task (e.g. the slippage of an object during grasping). Microfabricated neural electrodes implantable in peripheral nervous system seem a promising approach to this aim. New generation of thin-film intrafascicular electrodes longitudinally implantable in peripheral nerves (tf-LIFE4) has been developed and tested for afferent stimulation in human amputee case study.

On the control of a robot hand by extracting neural signals from the PNS: Preliminary results from a human implantation

The development of hybrid neuroprosthetic systems (HBSs) linking the human nervous system with artificial devices is an important area of research that is currently addressed by several groups to restore sensorimotor function in people affected by different disabilities. It is particularly important to establish a fast, intuitive, bidirectional flow of information between the nervous system of the user and the smart robotic device. Among the possible solutions to achieve this goal, interfaces with the peripheral nervous system and in particular intraneural electrodes can represent an interesting choice. In the present study, thin-film longitudinal intra-fascicular electrodes were implanted in the median and ulnar nerves of an amputee. The possibility of restoring the bidirectional link between the subject and the external world was investigated during a 4 week trial. The result showed that both the extraction of motor information and the restoration of sensory function are possible.

ODEs model of foreign body reaction around peripheral nerve implanted electrode

The foreign body reaction that the neural tissue develops around an implanted electrode contributes to insulate the probe and enhances the electrical and mechanical mismatch. It is a complex interaction among cells and soluble mediators and the knowledge of this phenomenon can benefits of formal and analytical methods that characterize the mathematical models. This work offers a lumped component model, described by ordinary differential equations, that taking into account the main geometrical (size, shape, insertion angle) and chemical (coating surface) properties of the implant predict the thickness of the fibrotic capsule in a time frame when the reaction stabilizes. This tool allows to evaluate different hypothetical solutions for accounting the tissue-electrode mismatch.

Preliminary investigations on laminin coatings for flexible polyimide/platinum thin films for PNS applications

The aim of this work was to investigate the possibility to obtain stable bioactive coatings for polyimide/platinum neural interfaces based on thin film technology for applications into the peripheral nervous system (PNS). Laminin (LI), a glycoprotein of the extracellular matrix, which guides and promotes differentiation and growth of neurons, was selected to deposit bioactive coatings. Dip-coating was performed on dummy structures at different LI concentrations. Indirect methods allowed to identify and characterize laminin on coated samples. Mechanical stability was also confirmed by indirect evaluations. Pilot experiments with differentiated PC12 cells, by the addition of nerve growth factor (NGF), showed improved neurite outgrowth on the coated probes compared to bare polyimide samples.

Optimization of a thermal slip sensor using FEM and dimensional analysis

During manipulation tasks it is important to maintain a precise and safe control of the grasping force. Slip detection plays a key role to assure an adequate adaptation of the grasping force, without object damaging. Several approaches to slip detection are currently under investigation. In particular, thermal slip sensors use a detection strategy similar to the one employed in hot wire anemometry, using a microfabricated thermal probe for detecting the convective heat flux associated to the movement of the touched object. This paper reports on the model-based optimization of a thermal slip sensor, intended for robotic prosthesis. In particular, an analytical thermal model has been developed, by merging FEM and dimensional analysis. A sensitivity analysis, performed on the parameters appearing in the model, has been performed for optimizing both sensors geometry and materials in order to increase the heat flux and thereby to obtain a reduction of response times in the identification of slip. Simulations on the proposed design indicate an expected increase of the thermal dissipated power of about 400%.

Conceptualization of an insect/machine hybrid controller for space applications

This paper reports the preliminary results of a research effort aiming at conceptualizing novel insect/machine hybrid controllers for autonomous exploratory vehicles. In particular, we investigate the possibility to include pre-developed animal intelligence capable of sensory-motor integration, decision-making and learning behaviors. In this context we present an in-depth review of insect neurophysiology focussing on mechanisms related to navigation. In addition we critically review current approaches towards hybridity and insect/machine interfaces. Finally, a novel insect/machine hybrid control architecture is proposed. It includes biological/artificial modules and deliberative/reactive behaviors.

Multisensor silicon needle for cardiac applications

An integrated chemical sensor with multiple ion and temperature sensors, composed of two ISFETs (pH and K/sup +/), one platinum pseudo-reference electrode and temperature sensor based on a platinum resistor has been realised by using a CMOS-compatible technology and silicon micromachining. This paper describes a summary of the fabrication process and results of the device characterisation in vitro. The feasibility of the fabrication technology has been demonstrated and all devices have operated satisfactory, with a response showing good sensitivity and linearity. This multisensor will be used in the on-line early detection of myocardial ischemia during cardiac surgery while the heart is artificially arrested (extracorporeal circulation).

Grasping the Future: Advances in Powered Upper Limb Prosthetics

Assessment tools are vital in measuring the outcomes of any practice or procedure. In the development and use of a prosthetic limb, this can be divided into three areas; the basic functions of the design, activities the limb is used for, and the amount the user actually employs the hand in everyday life. Each area is distinct and different and it needs different tools designed specifically for each area in order to reliably measure these outcomes. The development of these tools must include means to make sure the tool measures what the tester thinks it measures and makes sure that such measurements are consistent across time and between testers. Once a consistent set of tools is developed it allows clinicians to discuss and compare devices, training methods and solutions. It also allows investigation of different designs.Currently, the emphasis is on the basic practical measurements of function, activity and participation. This uses simple methods based on observation, timing or questionnaires to measure the use of simple prostheses. With newer designs of multifunction hands and microprocessor controllers being introduced, there are more varied control methods for the different hands. This requires more sophisticated methods to measure the impact of the new designs. These new methods include the measurement of the motions of the body and upper limbs with optical methods, and looking at measuring the cognitive load that controlling such hands impose on the user. To allow simple comparisons between users, the tasks and methods have to be constrained. This creates more artificial activities which may themselves be too artificial to tell the observer what they need to know, so the choice of activity is a balance between realistic tasks and reliable results.Assessment tools are vital in measuring the outcomes of any practice or procedure. In the development and use of a prosthetic limb, this can be divided into three areas; the basic functions of the design, activities the limb is used for, and the amount the user actually employs the hand in everyday life. Each area is distinct and different and it needs different tools designed specifically for each area in order to reliably measure these outcomes. The development of these tools must include means to make sure the tool measures what the tester thinks it measures and makes sure that such measurements are consistent across time and between testers. Once a consistent set of tools is developed it allows clinicians to discuss and compare devices, training methods and solutions. It also allows investigation of different designs. Currently, the emphasis is on the basic practical measurements of function, activity and participation. This uses simple methods based on observation, timing or questionnaires to measure the use of simple prostheses. With newer designs of multifunction hands and microprocessor controllers being introduced, there are more varied control methods for the different hands. This requires more sophisticated methods to measure the impact of the new designs. These new methods include the measurement of the motions of the body and upper limbs with optical methods, and looking at measuring the cognitive load that controlling such hands impose on the user. To allow simple comparisons between users, the tasks and methods have to be constrained. This creates more artificial activities which may themselves be too artificial to tell the observer what they need to know, so the choice of activity is a balance between realistic tasks and reliable results. - See more at: http://eurekaselect.com/103365/chapter/introduction-to-assessmen#sthash.CWvcyTj7.dpuf