Pair Of Fingers Research Articles

Boundaries of task-specificity: bimanual finger dexterity is reduced in musician’s dystonia

Task-specific dystonia leads to loss of sensorimotor control for a particular motor skill. Although focal in nature, it is hugely disabling and can terminate professional careers in musicians. Biomarkers for underlying mechanism and severity are much needed. In this study, we designed a keyboard device that measured the forces generated at all fingertips during individual finger presses. By reliably quantifying overflow to other fingers in the instructed (enslaving) and contralateral hand (mirroring) we explored whether this task could differentiate between musicians with and without dystonia. 20 right-handed professional musicians (11 with dystonia) generated isometric flexion forces with the instructed finger to match 25%, 50% or 75% of maximal voluntary contraction for that finger. Enslaving was estimated as a linear slope of the forces applied across all instructed/uninstructed finger combinations. Musicians with dystonia had a small but robust loss of finger dexterity. There was increased enslaving and mirroring, primarily during use of the symptomatic hand (enslaving p = 0.003; mirroring p = 0.016), and to a lesser extent with the asymptomatic hand (enslaving p = 0.052; mirroring p = 0.062). Increased enslaving and mirroring were seen across all combinations of finger pairs. In addition, enslaving was exaggerated across symptomatic fingers when more than one finger was clinically affected. Task-specific dystonia therefore appears to express along a gradient, most severe in the affected skill with subtle and general motor control dysfunction in the background. Recognition of this provides a more nuanced understanding of the sensorimotor control deficits at play and can inform therapeutic options for this highly disabling disorder.

Unveiling intra-person fingerprint similarity via deep contrastive learning.

Fingerprint biometrics are integral to digital authentication and forensic science. However, they are based on the unproven assumption that no two fingerprints, even from different fingers of the same person, are alike. This renders them useless in scenarios where the presented fingerprints are from different fingers than those on record. Contrary to this prevailing assumption, we show above 99.99% confidence that fingerprints from different fingers of the same person share very strong similarities. Using deep twin neural networks to extract fingerprint representation vectors, we find that these similarities hold across all pairs of fingers within the same person, even when controlling for spurious factors like sensor modality. We also find evidence that ridge orientation, especially near the fingerprint center, explains a substantial part of this similarity, whereas minutiae used in traditional methods are almost nonpredictive. Our experiments suggest that, in some situations, this relationship can increase forensic investigation efficiency by almost two orders of magnitude.

Vertebrate-conserved Schnurri zinc fingers restrain Drosophila vein patterning.

The Drosophila Smad-interacting co-factor, Schnurri (Shn) confers transcriptional repression in response to Decapentaplegic (Dpp) signaling. Shn zinc fingers 6-8 mediate this Smad interaction but are lacking in vertebrate Shn homologs. In contrast, the vertebrate-conserved zinc finger 1,2 and 4,5 pairs have been reported to engage in Smad-mediated transcriptional activation in fly and vertebrate systems, and to contribute to Dpp-dependent tissue repair in the fly retina. We report that mutation of zinc coordination residues within vertebrate-conserved Shn zinc finger pairs 1,2 and 4,5 results in ectopic venation that is sensitive to Dpp signaling.

A multi-device robotic-assisted PCI system: a proof-of concept study for left main bifurcation stenting with culotte technique in a porcine model

Background and purpose: Robotic-assisted percutaneous coronary intervention (PCI) has been increasingly used for simple lesion. For complex lesions, extensive manual intervention is still required. This study aims to verify the stability and safety of this robot system in complex lesion under fifth-generation (5G) network before clinical trial. Methods: We developed a robotic system that allows simultaneous remote control of multiple devices using a 5G wireless network. The key feature of the system is a bionic thumb along with two-bionic forefingers. The system was tested in eight pigs (six over 18.3 km and two over 1,100 km). Two stents were placed in the left main bifurcation using the culotte technique. All procedures, barring device loading onto the robot system, including manipulation of the guiding catheter, wire adjustments, stent or balloon positioning, and notably the final kissing step, were conducted remotely. Results: The rate of procedure success was 100%, with no device-related complications. In comparison to short-distance remote control, the delay with long-distance remote control was minimal (90.9 ± 1.5 vs. 81.5 ± 2.7 ms for command data transmission; 163.2 ± 1.3 vs. 161.0 ± 1.4 ms for image transmission). The procedure time was shorter when using two pairs versus a single pair of bionic fingers (104.3 ± 10.2 vs. 126.0 ± 3.9 min), primarily due to less time needed for device loading and exchange (33.1 ± 4.2 vs. 56.1 ± 4.0 min). Conclusions: With the 5G network, long distance was not a significant barrier for robotic-assisted PCI for chronic total occlusion. A design of the independent bionic finger module enabled final kissing balloon inflation with reduced requirement for manual intervention. Whether the system could be used beyond left main bifurcation lesions requires further investigation.

Structural design and analytical study of a new polysilicon tunable microactuator for measurement of different resonance frequencies

This paper presents a novel MEMS tunable resonator that draws inspiration from the folded beam structure in its comb drive resonator design. Conventional electrostatic comb-drive resonators commonly employ folded-beam suspensions to achieve linearity and reduce system stiffness. The proposed design incorporates eight zigzag-shaped meander springs to support the comb finger structure, featuring two central anchors. The objective of this design is to introduce zigzag-shaped nested-folded beam suspensions to the comb parts, thereby reducing the tuning voltage and sensor size. The governing equations are provided to calculate the support springs’ stiffness, and a comparative analysis is conducted to evaluate the stiffness of the proposed design against other parameters. The mathematical analysis demonstrates that Zigzag Nested-Folded beams result in a decreased resonance frequency and a softened electrostatic spring under applied DC voltage. The integration of zigzag-shaped nested-folded beam flexures enables MEMS resonator devices to exhibit reduced stiffness, leading to a lower pull-in voltage. The resonator design and simulation are performed using Intellisuite and SolidWorks software. Results indicate that the resonant frequency of the proposed tunable comb-drive resonator, equipped with 26 finger pairs and a movable part displacement of 21 μm, is reduced by 66% from the original frequency of 2.420 kHz when a tuning voltage of 59 V is applied. Simultaneously, the corresponding effective stiffness decreases by 66% from the initial value of 0.72 N m−1. This compact resonator occupies an area of approximately 1.058×278 (μm)2, demonstrating a smaller size compared to previous works.

Optimization of SAW Sensors for Nanoplastics and Grapevine Virus Detection

In this work, we report the parametric optimization of surface acoustic wave (SAW) delay lines on Lithium niobate for environmental monitoring applications. First, we show that the device performance can be improved by acting opportunely on geometrical design parameters of the interdigital transducers such as the number of finger pairs, the finger overlap length and the distance between the emitter and the receiver. Then, the best-performing configuration is employed to realize SAW sensors. As aerosol particulate matter (PM) is a major threat, we first demonstrate a capability for the detection of polystyrene particles simulating nanoparticulates/nanoplastics, and achieve a limit of detection (LOD) of 0.3 ng, beyond the present state-of-the-art. Next, the SAW sensors were used for the first time to implement diagnostic tools able to detect Grapevine leafroll-associated virus 3 (GLRaV-3), one of the most widespread viruses in wine-growing areas, outperforming electrochemical impedance sensors thanks to a five-times better LOD. These two proofs of concept demonstrate the ability of miniaturized SAW sensors for carrying out on-field monitoring campaigns and their potential to replace the presently used heavy and expensive laboratory instrumentation.

Structure of SALL4 zinc finger domain reveals link between AT-rich DNA binding and Okihiro syndrome.

Spalt-like 4 (SALL4) maintains vertebrate embryonic stem cell identity and is required for the development of multiple organs, including limbs. Mutations in SALL4 are associated with Okihiro syndrome, and SALL4 is also a known target of thalidomide. SALL4 protein has a distinct preference for AT-rich sequences, recognised by a pair of zinc fingers at the C-terminus. However, unlike many characterised zinc finger proteins, SALL4 shows flexible recognition with many different combinations of AT-rich sequences being targeted. SALL4 interacts with the NuRD corepressor complex which potentially mediates repression of AT-rich genes. We present a crystal structure of SALL4 C-terminal zinc fingers with an AT-rich DNA sequence, which shows that SALL4 uses small hydrophobic and polar side chains to provide flexible recognition in the major groove. Missense mutations reported in patients that lie within the C-terminal zinc fingers reduced overall binding to DNA but not the preference for AT-rich sequences. Furthermore, these mutations altered association of SALL4 with AT-rich genomic sites, providing evidence that these mutations are likely pathogenic.

Objective assessment of tapering of the fingers in adults.

Mild proximal-to-distal tapering of the fingers is a relatively common trait in humans. When more extreme, finger tapering is a feature observed in many genetic syndromes. The range of variation for finger tapering in the general population is not well understood, and sex differences in the degree of tapering, while suspected, have not been documented. Part of the difficulty is a lack of objective methods to evaluate finger tapering. In the present report, we developed a tapering index based on linear measures derived from digital hand scans. We measured this index in a sample of 166 male and 166 age-matched female adults. We then looked at correlations both among fingers and with demographic and anthropometric variables, followed by tests for sex differences. We observed weak correlations between tapering and age, height and weight. Correlations between pairs of fingers tended to be more in the moderate range and were highest among the middle three fingers (ranging from 0.34 to 0.64). Tapering tended to increase slightly moving radially across the hand from the fifth finger to the second finger. Males showed less tapering than females for all fingers, with statistically significant differences involving the left second finger (p = 0.003), left fifth finger (p< 0.001), right second finger (p = 0.038), and right fourth finger (p = 0.021). Finally, we established baseline norms for both males and females out to three standard deviations. Our results indicate that finger tapering is present, to some degree, in most of the population and that the trait can be measured using a relatively simple and non-invasive method. These findings may have relevance for fields as diverse as medical genetics, forensics, and industrial design.

Triboelectric based high-precision self-powering cage skidding sensor and application on main bearing of jet engine

Monitoring the dynamic behavior of rolling bearings is important to ensure the reliability of rotating machinery. In this study, a novel, high-precision, self-powering triboelectric bearing skidding sensor (HP-TEBSS) is developed for the real-time monitoring of bearing skidding degree and cage stability characteristics. A floating sweeping, freestanding mode is adopted to ensure long-term reliability, and the HP-TEBSS does not affect the bearing structure and dynamic behavior. The proposed sensor consists of an interdigital electrode plate, a dielectric ring with a protruding surface, and a fixed ring. The dielectric ring, which is pasted to the side surface of the integral copper cage, rotates synchronously with the cage and sweeps to the electrode plate. The HP-TEBSS generates Ne (number of electrode finger pairs) times of instantaneous cage speed information than that of commercial sensor, and the deviation between these two sensors is less than 1%. This shows the advanced real-time performance and monitoring accuracy of the proposed sensor. Experiments are conducted under variable working conditions with different structural parameters to optimize the sensor output performance. The self-powering and 50 h durability capabilities of the HP-TEBSS are demonstrated. Bearing skidding and cage rotation stability under variable spindle rotation speeds and bearing axial loads are systematically evaluated. It was found that in the light-load range, the skidding degree showed an increasing trend as the speed increased, whereas it showed the opposite trend under the heavy-load range. The monitoring results of cage speed fluctuations, which indicate running stability, provide recommendations for preventing bearing operation in the vulnerable range. Furthermore, the proposed bearing dynamic model is validated using the HP-TEBSS test results to demonstrate the wide applicability, high portability, and high-speed performance of the HP-TEBSS prototype. The application of the HP-TEBSS on a high-speed jet engine test bench is analyzed. It is found that cage skidding shows a certain degree of hysteresis in the deceleration stage, as compared to the acceleration stage, owing to cage inertia. Finally, theoretical and experimental aspects of the presented self-powering multifunctional HP-TEBSS that can be applied in the smart rolling bearing field are presented.

Maneuver and formation control of a pair of soft pneumatic bending fingers by a cooperative strategy for planar in-hand object manipulation

In this paper, we seek performing dynamic in-hand object manipulation with two-segmented soft fingers in 2-D plane. Thereby, after the dynamic behavior of the soft fingers was defined, we evaluate the influence of external tip force on the finger. It is shown that the tip position error, under the effect of tip force, can be represented by uncertainties in kinematic parameters of the finger. As a result, we design a sliding-adaptive controller with compensation of kinematic uncertainties to fulfill our expectation that is controlling the tip position of the finger in vertical plane while interacting with the environment. Finally, inspired by the way that human fingers manipulate an object, a cooperative control system for manipulation is proposed which incorporates the states and tip positions of the fingers in its feedback signal. Combination of this controller with the adaptive control system yields more promising results than does the PID controller. In order to evaluate performance of the proposed controller, Simulation results for manipulation of a cubic rigid object are demonstrated.

A microfluidic biosensor for rapid simultaneous detection of waterborne pathogens

A microfluidic based biosensor was investigated for rapid and simultaneous detection of Salmonella, Legionella, and Escherichia coli O157:H7 in tap water and wastewater. The biosensor consisted of two sets of focusing electrodes connected in parallel and three sets of interdigitated electrodes (IDE) arrays. The electrodes enabled the biosensor to concentrate and detect bacteria at both low and high concentrations. The focusing region was designed with vertical metal sidewall pairs and multiple tilted thin-film finger pairs to generate positive dielectrophoresis (p-DEP) to force the bacteria moving toward the microchannel centerline. As a result, the bacterial pathogens were highly concentrated when they reached the detection electrode arrays. The detection IDE arrays were coated with three different antibodies against the target bacterial pathogens and a cross-linker to enhance the binding of antibodies to the detection electrode. As the binding of bacterial pathogen to its specific antibodies took place, the impedance value changed. The results demonstrated that the biosensors were capable of detecting Salmonella, Legionella, and E. coli 0157:H7 simultaneously with a detection limit of 3 bacterial cells/ml in 30 − 40 min.

Simulating the piezoelectric substrate influence on the characteristics of surface acoustic wave-magnetostriction sensor based on the FeNi magnetic sensitive material

This paper simulates the influence of two piezoelectric substrate types on the sensitivity and measuring range of surface acoustic wave-magnetostriction (SAW-MO) sensor by the finite elements method (FEM) based on using the FeNi magnetic sensitive layer with E-H chacrateristics (Young’s Modulus – Magnetic field intensity). The sensor structure selected for the study is the delay-line: the distance between the two sets of electrodes is 5mm, the number of finger pairs of each electrode set is 25, and the distance-width between the fingers is 10m regularly, the electrode material is aluminum. The piezoelectric substrates chosen for simulation are LiNbO3 and AlN in which the LiNBO3 piezoelectric substrate is the block form with the surface velocity of 3318.1m/s and the AlN piezoelectric substrate is the thin film with the surface wave velocity of 5598.9m/s. So the generality is ensured when evaluating their influence on the response of SAW-MO sensor. For magnetic sensitive materials, the group selected the FeNi which E-H characteristics was experimentally built. During simulation by finite elements method, the sensor structure is tested with many datasets whose number of divided elements is different. However, the simulation results have converged with the number of divided elements is 113556. The simulation result shows that the sensivity of the FeNi/IDT/AlN structure magnetic sensor is larger than the FeNi/IDT/LiNbO3 structure magnetic sensor with sensitivities of 8.698kHz/Oe and 2.345kHz/Oe, respectively. The result also indicates that the response range of the FeNi/IDT/AlN magnetic sensor is [0 ÷ 109]Oe, which is smaller than the FeNi/IDT/LiNbO3 magnetic sensor is [0 ÷ 190]Oe.

Field nonuniformity of limited-aperture planar SAWs and its implications for designing SSAW acoustofluidics

Acoustofluidics operating at high frequencies usually use surface acoustic waves (SAWs), and those emitted by limited-aperture planar interdigital transducers (IDTs) are prevalent. In such devices, field nonuniformity along the lateral direction is observed by many, but there lacks a study to quantitatively clarifying this effect. Here, by modeling IDTs using dirac-type transfer functions, we examine how field nonuniformity changes at varied aperture length, axial distance, and number of finger pairs of the IDTs. For standing SAW (SSAW) devices, field predictions from numerical analysis are validated through experimental measurements employing laser vibrometry. Finally, particle acoustophoresis is carried out in three SSAW devices, while the results provide some useful implications for future device designs.

Features of Index-Ring Finger Pair’s Force Contribution in Multi-Finger Force-Following Tasks

New types of cylindrical handles such as pushrims with force signal sensors under four fingers (excluding the thumb) enable real-time gripping-status assessment. The mirrored change phenomenon of the index and ring fingers observed in linear grip tasks offers a new perspective on finger grouping. To evaluate the force contribution of index-ring finger pair in multi-finger force, 10 right-handed male participants with similar hand sizes were recruited to participate in sinusoidal function force-following tasks involving a cylindrical handle. The real-time signal of the grip force and individual finger force were recorded to analyze real-time changes in the finger force contribution (FC). Subsequently, the time-FC curves of individual and paired fingers were analyzed. Results show are as follows: (1) When the FC of the index-ring finger pair exceeded that of the middle-little finger pair, the gripping load was relatively low, and a smaller difference between the FCs of the index-ring finger pair and the middle-little finger pair indicated a smaller following error. (2) The FC of index-ring finger pair is a better (higher-linearity) parameter to assess gripping status. These findings show that the paired-finger FC is an adequate parameter for the gripping-status assessment.

Sensitivity of Surface Acoustic Wave Sensors Based LiNbO3 128° Y-X and at-Quartz to PM10 and PM2.5

IntroductionParticulate matter (PM) was estimated to cause around 7 million premature deaths worldwide per year according to World Health organization [1]. These particles can cause diseases leading to premature death [2]. Over the last decade, the monitoring of PM became an important issue on a worldwide scale. The miniaturization of the existing bulky systems has also become necessary to reduce their cost. To address this need, a new miniaturized system for PM monitoring was previously developed in our team [3]. It takes advantage of both a 3 Lpm cascade impactor and surface acoustic waves (SAW) sensors to respectively separate and measure particles. The present study aims to compare the sensitivity of two SAW devices. The first exploits Love waves on an AT cut Quartz substrate and the second is based on Rayleigh waves from a LiNbO3 Y-X 128° substrates. The latter presents a high electromechanical coupling factor that could be exploited for the self-cleaning of the device after the measurement. This could allow overcoming the fouling issue faced with impactors that wouldn’t be solved with quartz based sensors which suffer from an insufficient electromechanical coupling. Method In this study we used a dedicated 3 Lpm cascade impactor equipped with SAW delay lines as collecting plate. The Rayleigh wave sensor and the Love wave sensor were designed and fabricated respectively on LiNbO3 Y-X 128° cut and AT-Quartz cut substrates using a conventional photolithography process. The interdigital transducers (IDT) consist of double finger pairs made of 200 nm thick aluminum with a periodicity p=10 µm and a wavelength λ=40 µm. Hence, the working frequency is 125 MHz for the Love mode and 98 MHz for the Rayleigh mode. The propagation of Love wave needs a guiding layer. For that purpose, a silica layer was deposited using sputtering technique with shear velocity lower than the piezoelectric substrates. The region between the two IDTs constitutes the sensing area.Preliminary tests have been performed using candle smoke. As the obtained PM concentrations were unstable and difficult to reproduce, we have developed an experimental set-up bench consisting of a 1m3 chamber, a particle’s generator AGK 2000 and an optical system FIDAS® 100. Thus, sodium chloride (NaCl) was used to produce PM2.5 while PM10 were generated from silicon carbide (SiC) in the 0 to 200 μg/m3 concentration range. When the particles impact on the sensor surface, the velocity of the acoustic waves decreases due to the sensors’ high gravimetric sensitivity. Accordingly, the wave phase velocity shift is measured by monitoring the phase at constant frequency with an open loop interrogation [4]. It’s then correlated to the particles concentration. Results and Conclusions Figure 1 and 2 shows plots of phase derivative dϕ/dt of sensors based AT-Quartz (black) and LiNbO3 (red) with the concentration of PM10 and PM2.5 respectively measured with the optical system FIDAS®. As expected, the sensitivity of the Rayleigh wave sensor based on LiNbO3 is lower than the Love wave sensor based on quartz for both PM10 and PM2.5. The sensor’s sensitivity is estimated by applying a linear fit of the plotted data. The sensitivity of sensors based on quartz is 3.10-4 °/s.μg/m3 for PM 2.5 and 5.10-5 °/s.μg/m3 for PM10. For sensors based on LiNbO3, the sensitivity is 1.10-4 °/s.μg/m3 for PM2.5 and 1.10-5 °/s.μg/m3 for PM10. The feature that the sensors’ response is greater with PM2.5 than with PM10 can be explained by the fact that most adhesion forces are linearly dependent on particle diameter [5] which is often described as the rebound effect. As a result, the smaller particles settle more on the surface of the sensor resulting in a more significant slowdown of the wave. To ensure that each stage is measuring the targeted size range, we took images of the sensors surface at the end of the experiment using a microscope. Figures 3, 4 show the surface of the PM2.5 stage and figures 5, 6 the one of the PM10 stage. One can observe that, as expected, the PM2.5 contain more particles than the PM10 and that the particle sizes correspond well to the ranges [0.3 μm, 2.5 μm] and [2.5 μm, 10 μm]. It has therefore been shown that LiNbO3 sensors, although less sensitive, can also be used for fine particles detection. They still need work to improve their performance and limit the rebound effect, but they remain very promising for the development of self-cleaning systems.

Salient Properties in Bimanual Haptic Volume Perception: Influence of Object Shape, Finger Pair, and Schizotypal Personality Traits.

Bimanual haptic volume perception refers to somatosensory access to volume information through both hands, and the characteristics that influence this perception remain unclear. This article investigated the influence of target object shapes and finger pairs on bimanual haptic perception; in addition, associations of bimanual haptic impairment and schizotypal features in nonpsychotic individuals were investigated. Twenty blindfolded participants bimanually discriminated volume variations in regular solid objects under different shape (tetrahedron, cube, or sphere) and finger pair (high- or low-sensitivity pairs) conditions using a newly developed bimanual haptic volume presentation device. Discrimination thresholds were then associated with schizotypal traits using the Chinese version of the Schizotypal Personality Questionnaire. Target object shape and finger pairs significantly influenced bimanual haptic volume perception. Volume discrimination thresholds were significantly higher with the tetrahedron stimuli than the cubic or spherical stimuli in high-sensitivity pair conditions, but no significant differences among shapes were found in low-sensitivity pair conditions. Moreover, volume discrimination thresholds with high-sensitivity pairs were correlated with the paranoid score of the schizotypal personality questionnaire. The findings provide initial evidence toward understanding the nature of bimanual haptic volume perception, including the properties of objects, individuals, and object-individual interfaces.

Effects of Daily Hand Activities on Age-Related Declines of Dynamic Motor Function in Individual Fingers

The present study examined the effects of daily activities of the hands on finger motor function in older adults. Maximum tapping frequency with each finger during single-finger tapping and alternate movements of index-middle, middle-ring, and ring-little finger pairs during double-finger tapping were compared between older adults who used their hands actively in their daily lives and those who did not. The active participants had significantly faster tapping rates for the ring finger in the single-finger tapping and the middle-ring finger pair in the double-finger tapping than did the inactive participants. Thus, daily activity of the hands in older adults could be effective at preventing the loss of dynamic motor function in individual fingers, especially with greater difficulty in movement, resulting from the degeneration with age.

Distortions of the Efferent Copy during Force Perception: A Study of Force Drifts and Effects of Muscle Vibration

We used a finger force matching task to explore the role of efferent signals in force perception. Healthy, young participants performed accurate force production tasks at different force levels with the index and middle fingers of one hand (task-hand). They received visual feedback during an early part of each trial only. After the feedback was turned off, the force drifted toward lower magnitudes. After 5 s of the drift, the participants matched the force with the same finger pair of the other hand (match-hand). The match-hand consistently overshot the task-hand force by a magnitude invariant over the initial force levels. During force matching, both hands were lifted and lowered smoothly to estimate their referent coordinate (RC) and apparent stiffness values. These trials were performed without muscle vibration and under vibration applied to the finger/hand flexors or extensors of the task-hand or match-hand. Effects of vibration were seen in the match-hand only; they were the same during vibration of flexors and extensors. We interpret the vibration-induced effects as consequences of using distorted copies of the central commands to the task-hand during force matching. In particular, using distorted copies of the RC for the antagonist muscle group could account for the differences between the task-hand and match-hand. We conclude that efferent signals may be distorted before their participation in the perceptual process. Such distortions emerge spontaneously and may be amplified by the response of sensory endings to muscle vibration combined over both agonist and antagonist muscle groups.

Design of Soft Grippers with Modular Actuated Embedded Constraints

Underactuated, modular and compliant hands and grippers are interesting solutions in grasping and manipulation tasks due to their robustness, versatility, and adaptability to uncertainties. However, this type of robotic hand does not usually have enough dexterity in grasping. The implementation of some specific features that can be represented as “embedded constraints” allows to reduce uncertainty and to exploit the role of the environment during the grasp. An example that has these characteristics is the Soft ScoopGripper a gripper that has a rigid flat surface in addition to a pair of modular fingers. In this paper, we propose an upgraded version of the Soft ScoopGripper, developed starting from the limits shown by the starting device. The new design exploits a modular structure to increase the adaptability to the shape of the objects that have to be grasped. In the proposed device the embedded constraint is no rigid neither unactuated and is composed of an alternation of rigid and soft modules, which increase versatility. Moreover, the use of soft material such as thermoplastic polyurethane (TPU) reduces the risk of damage to the object being grasped. In the paper, the main design choices have been exploited and a finite element method (FEM) analysis through static simulation supports a characterization of the proposed solution. A complete prototype and some preliminary tests have been presented.

Finger interdependence and unintentional force drifts: Lessons from manipulations of visual feedback.

We explored the phenomenon of unintentional finger force drift by using visual feedback on the force produced either by explicitly instructed (master) finger pairs or by non-instructed (enslaved) finger pairs. In particular, we drew contrasting predictions from two hypotheses: that force drifts represented consequences of drifts in effector referent coordinates at the level of individual fingers vs. at the level of finger modes (hypothetical variables accounting for the finger force interdependence). Subjects performed accurate force production with two fingers of a hand, index-ring or middle-little. They received visual feedback on the force produced either by the master fingers or by the other two, enslaved, fingers. The feedback scale was adjusted to ensure that the subjects did not know the difference between these two, randomly presented, conditions. Under feedback on the master finger force, enslaved force showed a consistent drift upward. Under feedback on the enslaved finger force, master force showed a consistent drift downward. The subjects were unaware of the force drifts, which could reach over 35% of the initial force magnitude. The data support the hypothesis on drifts in the referent coordinate at the level of individual digits, not finger modes, as the origin of unintentional force drifts. The consistent increase in the relative amount of force produced by the enslaved fingers suggests that the commonly used methods to quantify enslaving should include relatively brief force production tasks.