Movable Finger Research Articles

Development of Self-Powered Prosthetic Finger with Pneumatic Passive Joints for Distal Interphalangeal Joint Amputees

Myoelectric prosthetic hands and fingers with grasping functions have challenges such as weight, cost, and grasping performance of flexible objects owing to the use of electric actuators. To resolve these problems, we propose a self-powered movable prosthetic finger using pneumatic pressure. This prosthetic finger utilizes the flexion/extension of the remaining finger of the user to drive a wire and flex or extend the finger joints. The use of a tendon (wire) and belt drives reduces the space occupied by the prosthetic finger unit compared with conventional linked prosthetic fingers. Furthermore, a sealed-air bellows is used for the joint for flexible grasping owing to passive variable-compliance and damping, which is impossible with only a tendon drive. These features have resulted in the stable grasping of various objects that are difficult to grasp using prosthetic fingers based on conventional technologies.

Three new Geogarypidae (Pseudoscorpiones: Garypoidea) from South Africa, with an updated key to the country’s geogarypid species

Two new species of Afrogarypus Beier, 1931, A. haddadi sp. nov. and A. pseudotriangularis sp. nov., and a new species of Geogarypus Chamberlin, 1930, G. grandis sp. nov. are described. Afrogarypus haddadi sp. nov. is diagnosed by a reduced isb and five rami on the female galea. Afrogarypus pseudotriangularis sp. nov. is diagnosed by trichobothria eb, esb, ib, est, isb, b, sb and st grouping within the first half of the fixed finger length and ten rami on the female galea. Geogarypus grandis sp. nov. is unique from the rest of its South African conspecifics in having two additional basal setae on the cheliceral hand, pedipalps densely ornamented with distinct protuberances and a unique protuberance at the base of the movable chelal finger. An updated identification key to the Geogarypidae species of South Africa is also presented.

4D Printing of novel poly(ethylene-vinyl acetate) / poly(butyl methacrylate-co-isobutyl methacrylate) shape memory polymer blends

4D printing is a technology that combines additive manufacturing with shape memory polymers, aiming to enhance the functionality of 3D printed structures. Filaments made from thermoplastic polymers are commonly used in Fused Deposition Modeling (FDM), which is one of the most prevalent types of 3D printing. Here, novel heat-responsive shape memory polymer blends were produced from ethylene-vinyl acetate copolymer (EVA) and poly(butyl methacrylate-co-isobutyl metacrylate) polymers. The effect of blend composition on the morphological, thermal, mechanical, and shape memory properties was investigated. The blend (60E-40B) containing 60 % by weight EVA and 40 % by weight BMA-co-iBMA exhibited optimum shape memory performance with a shape fixing (Rf) of 94.1 % and a shape recovery (Rr) of 94.5 % at a shape transition temperature (Ttrans) of 55 °C. Filament for the 60E-40B blend was produced for FDM type 3D printers, and 4D parts for various applications were printed using this filament. These 4D printed parts, designed for robotic grippers, self-assemble rivets, movable cog-wheel teeth, surface traps, and finger splints, displayed shape recovery characteristics in both hot oven and hot water environments.

Mechanical Resistance of the Largest Denticle on the Movable Claw of the Mud Crab.

Decapod crustaceans have tooth-like white denticles that are present only on the pinching side of the claws. In the mud crab, Scylla serrata, a huge denticle exists on the movable finger of the dominant claw. This is mainly used to crush the shells of the crab's staple food. The local mechanical properties, hardness (HIT) and elastic modulus (Er), of the peak and valley areas of the largest denticle were examined via a nanoindentation test. The microstructure and elemental composition were characterized using a scanning electron microscope and energy-dispersive X-ray spectroscopy. The striation patterns originating from a twisted plywood structure parallel to the surface were visible over the entire denticle. Most of the largest denticle was occupied by a hard area without phosphorus, and there was a soft layer corresponding to the endocuticle with phosphorus in the innermost part. The HIT of the denticle valley was about 40% lower than that of the denticle peak, and the thickness of the soft endocuticle of the denticle valley was five times thicker than that of the denticle peak. The HIT-Er map showed that the abrasion resistance of the denticle surface was vastly superior and was in the top class among organisms. The claw denticles were designed with the necessary characteristics in the necessary places, as related to the ecology of the mud crab.

Austropallene halanychi sp. nov., a new species of sea spider (Pycnogonida, Callipallenidae) from the Ross Sea, Antarctica

Here we present Austropallene halanychisp. nov., a new species of pycnogonid within the family Callipallenidae (Pycnogonida), collected from the Ross Sea, Antarctica. While retaining key morphological features known for the genus Austropallene Hodgson, 1915a, the new species is distinguished from congeners by its much larger size, along with the combined absence of a denticle on the inner surface of the fixed finger of the chelifore claw along with the presence of small conical outgrowths where the fixed finger of the chelifore claw meets the movable finger on both the dorsal and ventral sides, and also the ability to fully close the chelifore claw. Additionally, the complete mitochondrial genome of A. halanychi is consistent with other members of the genus Austropallene in terms of gene order and directionality. A phylogenetic tree consisting of mitochondrial protein-coding gene data places A. halanychi as sister to Austropallene cornigera (Möbius, 1902). Additionally, a phylogenetic tree constructed using partial COI data from other callipallenids placed the new species in a clade containing the genus Austropallene. The combination of molecular data in addition to key morphological differences from similar species in the genus leaves no doubt that the new taxon is a new Antarctic species of Austropallene.

Revision of the genera Eutrecha and Xenotrecha (Solifugae: Ammotrechidae), taxonomic notes on Ammotrechinae, and description of a remarkable new Eutrecha from Colombia

The solifuge generaEutrechaMaury, 1982 andXenotrechaMaury, 1982 are among the rarest and most elusive groups of camel spiders in the New World. Since their inception, both genera have remained unclassified within the subfamilial scheme of Ammotrechidae, where they belong, and their systematic position and affinities to other genera continue to be unexplored. This contribution addresses the affinities thatEutrechaandXenotrechahave to the type genus of Ammotrechinae,AmmotrechaBanks, 1900. Based on the taxonomic distribution of characters shared by these genera, it is proposed that the three are closely related and classified into Ammotrechinae. Revised diagnoses are presented for Ammotrechinae s.str.,Eutrecha, andXenotrecha, and redescriptions are presented for species of these genera, when possible. A new species,Eutrecha belenensissp. nov., is described from Colombia, raising to three the number of species in the genus. New material ofEutrecha floreziVillareal-Blanco, Armas and Martínez, 2017 andXenotrecha huebneri(Kraepelin, 1899) is referenced, thus extending the distribution range of these species in Colombia and Brazil, respectively. Ammotrechinae s.str. is here defined by the presence of a retroventral longitudinal carina on the movable finger of the chelicerae and a cleavage plane basally on the femur of pedipalps, among other characters. The cleavage plane allows the pedipalp to be autotomized, representing the first report of pedipalp autotomy in Solifugae. This work also presents a discussion on the taxonomy of Ammotrechidae and delves into some aspects that affect the current delimitation of some of its subfamilies.

Three new species of cave-adapted pseudoscorpions (Pseudoscorpiones, Chthoniidae) from eastern Yunnan, China.

Three new cave-adapted chthoniid pseudoscorpions from four karst caves of Yunnan Province (China) are described, including detailed diagnosis and illustrations: Tyrannochthoniuscalvatussp. nov. from an unnamed cave and Dongtianfu Cave (Fuyuan County), T.capitosp. nov. from Xianren Cave (Xichou County), and Lagynochthoniusdaidaiensissp. nov. from Daidai Cave (Qiubei County). All three species are endemic to Yunnan. Tyrannochthoniuscalvatussp. nov., lacking the carapaceal antero-median setae and having intercalary teeth on the movable chelal finger only, is a peculiar chthoniid species.

The multi-grip and standard myoelectric hand prosthesis compared: does the multi-grip hand live up to its promise?

BackgroundMulti-grip myoelectric hand prostheses (MHPs), with five movable and jointed fingers, have been developed to increase functionality. However, literature comparing MHPs with standard myoelectric hand prostheses (SHPs) is limited and inconclusive. To establish whether MHPs increase functionality, we compared MHPs with SHPs on all categories of the International Classification of Functioning, Disability, and Health-model (ICF-model).MethodsMHP users (N = 14, 64.3% male, mean age = 48.6 years) performed physical measurements (i.e., Refined Clothespin Relocation Test (RCRT), Tray-test, Box and Blocks Test, Southampton Hand Assessment Procedure) with their MHP and an SHP to compare the joint angle coordination and functionality related to the ICF-categories ‘Body Function’ and ‘Activities’ (within-group comparisons). SHP users (N = 19, 68.4% male, mean age = 58.1 years) and MHP users completed questionnaires/scales (i.e., Orthotics and Prosthetics Users’ Survey—The Upper Extremity Functional Status Survey /OPUS–UEFS, Trinity Amputation and Prosthesis Experience Scales for upper extremity/TAPES-Upper, Research and Development-36/RAND-36, EQ-5D-5L, visual analogue scale/VAS, the Dutch version of the Quebec User Evaluation of Satisfaction with assistive technology/D-Quest, patient-reported outcome measure to assess the preferred usage features of upper limb prostheses/PUF-ULP) to compare user experiences and quality of life in the ICF-categories ‘Activities’, ‘Participation’, and ‘Environmental Factors’ (between-group comparisons).Results‘Body Function’ and ‘Activities’: nearly all users of MHPs had similar joint angle coordination patterns with an MHP as when they used an SHP. The RCRT in the upward direction was performed slower in the MHP condition compared to the SHP condition. No other differences in functionality were found. ‘Participation’: MHP users had a lower EQ-5D-5L utility score; experienced more pain or limitations due to pain (i.e., measured with the RAND-36). ‘Environmental Factors’: MHPs scored better than SHPs on the VAS-item holding/shaking hands. The SHP scored better than the MHP on five VAS-items (i.e., noise, grip force, vulnerability, putting clothes on, physical effort to control) and the PUF-ULP.ConclusionMHPs did not show relevant differences in outcomes compared to SHPs on any of the ICF-categories. This underlines the importance of carefully considering whether the MHP is the most suitable option for an individual taking into account the additional costs of MHPs.

Immature chaerilid scorpions from mid-Cretaceous amber of northern Myanmar (Arachnida: Scorpiones: Chaeriloidea)

Extant scorpions of the small family Chaerilidae are very sparse, and they are poorly documented in the fossil record. Here we describe two immature chaerilids from mid-Cretaceous amber of northern Myanmar based on multiple imaging methods. Our specimens can be unambiguously assigned to Chaerilus in family Chaerilidae based on their complete type B trichobothrial pattern, very broad anterior margin of maxillary lobes I, serrated ventral denticle of cheliceral movable finger, presence of pectinal fulcra, and spiniform setae on the ventral surface of tarsi.

Conceptualization of an Anthropomorphic Replacement Hand with a Sensory Feedback System

In this paper, a concept for an anthropomorphic replacement hand cast with silicone with an integrated sensory feedback system is presented. In order to construct the personalized replacement hand, a 3D scan of a healthy hand was used to create a 3D-printed mold using computer-aided design (CAD). To allow for movement of the index and middle fingers, a motorized orthosis was used. Information about the applied force for grasping and the degree of flexion of the fingers is registered using two pressure sensors and one bending sensor in each movable finger. To integrate the sensors and additional cavities for increased flexibility, the fingers were cast in three parts, separately from the rest of the hand. A silicone adhesive (Silpuran 4200) was examined to combine the individual parts afterwards. For this, tests with different geometries were carried out. Furthermore, different test series for the secure integration of the sensors were performed, including measurements of the registered information of the sensors. Based on these findings, skin-toned individual fingers and a replacement hand with integrated sensors were created. Using Silpuran 4200, it was possible to integrate the needed cavities and to place the sensors securely into the hand while retaining full flexion using a motorized orthosis. The measurements during different loadings and while grasping various objects proved that it is possible to realize such a sensory feedback system in a replacement hand. As a result, it can be stated that the cost-effective realization of a personalized, anthropomorphic replacement hand with an integrated sensory feedback system is possible using 3D scanning and 3D printing. By integrating smaller sensors, the risk of damaging the sensors through movement could be decreased.

A new species of Epichernes (Pseudoscorpiones: Chernetidae) associated with rodents in Costa Rica

ABSTRACT The genus Epichernes Muchmore, 1982 has three Neotropical species with specific rodent hosts. Epichernes vickeryae sp. nov. is here described from Monteverde, Puntarenas, Costa Rica: the specimens were collected from a spiny pocket mouse Heteromys nubicolens. The new species, named E. vickeryae, is closer to E. navarroi by the position of trichobothria setae ist and isb, which are adjacent and the number of teeth on the movable finger, known from Mexico. The new species is characterized by trichobothrium ist adjacent to isb, femur L/B 1.71–1.85, it has 22–31 external accessory teeth, 58 teeth on fixed finger and 62 on movable finger. The carapace ranging from 1.12 mm to 1.33 mm in length, central tergites with 21–22 setae, chelicera with five setae on the hand, sb and b denticulate. The new species represents the second known species of Epichernes from Costa Rica.

A design of bionic soft gripper for automatic fabric grasping in apparel manufacturing

As a robot end-effector, the soft gripper shows good flexibility and adaptability in the process of grasping the fabric, which provides a new solution for garment production automation. In this article, a soft gripper like a high-heeled shoe was proposed which can separate the fabric layer by layer with high effectiveness. First, by observing the action of human hands grasping fabric, a soft gripper with a fixed finger and a movable finger was designed. Then, the structural parameters, such as the height difference between the fixed finger and the movable finger, the finger’s opening width, and the thickness of cavity of the designed soft finger are determined through force analysis and finite-element analysis. Further, a method was proposed to evaluate the positioning precision after the transportation of cutting pieces. Finally, soft grippers with three different parameters were made by three-dimensional printing to test their performance in grasping fabrics, and the accuracy of separating pieces of fabric layer by layer and the precision of positioning the fabric were tested, respectively. The results show that when the soft gripper with d = 1 mm is used to grasp different fabrics, the accuracy of layer-by-layer separation is above 90%. After the gripper is opened and the fabric is released, the positioning precision of most fabrics gets a tolerance of ±1 mm. Experimental results show that the soft gripper designed in this paper can behave like human hands to operate the motion of grasping fabrics in the manufacturing of garments.

Macrobrachium irwini sp. nov., a new species of freshwater shrimp from Western Ghats, India (Caridea: Palaemonidae)

A new species of the freshwater shrimp of the genus Macrobrachium irwini sp. nov., is described from the Nandhini River near Kateel, Karnataka region of Western Ghats, India. 11 specimens of Macrobrachium irwini sp. nov. were collected from Nandhini river running through a secondary forest with heavily vegetated banks. The morphological analyses revealed that the new species can be clearly distinguished from the closely related species, M. snpurii and M. scabriculum based on the shape and dentition on rostrum, antennular peduncle, segmental ratios of first pereiopod, tubercles along the cutting edges of immovable and movable fingers of second major pereiopod and telson. Additionally, we provided the striking colour patterns on the new species which could be distinguish this species from congeneric species.

Closed-loop MOEMS accelerometer.

In this paper, a closed-loop micro-opto-electro-mechanical system (MOEMS) accelerometer based on the Fabry-Pérot (FP) interferometer is presented. The FP cavity is formed between the end of a cleaved single-mode optical fiber and the cross-section of a proof mass (PM) which is suspended by four U-shaped springs. The applied acceleration tends to move the PM in the opposite direction. The arrays of fixed and movable comb fingers produce an electrostatic force which keeps the PM in its resting position. The voltage that can provide this electrostatic force is considered as the output of the sensor. Using a closed-loop detection method it is possible to increase the measurement range without losing the resolution. The proposed sensor is fabricated on a silicon-on-insulator wafer using the bulk micromachining method. The results of the sensor characterization show that the accelerometer has a linear response in the range of ±5 g. In the closed-loop mode, the sensitivity and bias instability of the sensor are 1.16 V/g and 40 µg, respectively.

Fighting does not influence the morphological integration of crustacean claws (Decapoda: Aeglidae)

Abstract Animal weapons are generally complex systems composed of more than one structure. A crab’s claw, for instance, is composed of a dactyl (a movable finger) and a propodus (where the muscle resides). Any weapon feature that increases winning probability also increases an individual’s fitness, meaning that all moving parts of a weapon will be under the same selective force—increasing their integration. By comparing weapons to homologous structures not used for fighting, we can test whether fighting increases morphological integration. Here, we tested that hypothesis by comparing the right (non-fighting) and left (fighting) claws of males of Aegla. First, we tested if the shape and size of the propodus and dactyl differed between claws. Then, we compared the degree of morphological integration. We showed that claws differed in their shape and size, but both claws showed similarly high levels of integration. This pattern can occur if selection favours an adequate squeeze on both claws, even though squeezing performance might differ between the claws. Nevertheless, the dactyl is important in determining the integration of a claw but it has been greatly ignored in crustacean studies and its study might increase our knowledge of claw evolution.

The genus Pseudocleobis Pocock, 1900 (Solifugae: Ammotrechidae) in transitional Patagonia-Monte deserts, with descriptions of two new species.

Two new solifuge species of the genus Pseudocleobis (Solifugae, Arachnida) from northern Patagonia and southern Monte desert biogeographical regions are described: P. mauryi sp. nov. and P. profanus sp. nov. New records of P. huinca Maury, 1976, P. bardensis Maury, 1976 and P. solitarius Maury, 1976 are provided. The female of P. solitarius is described based on specimens from the type locality. SEM photographs, schemes of diagnostic characters, and maps of the known distributional records are provided for the five species treated here. Pseudocleobis profanus sp. nov. is closely related to P. huinca and P. bardensis, and the three species may form a species group characterized by the peculiar morphology of the male movable finger mucron and the flagellum. Ctenidia on male sternite III and IV are reported for the five species.

Wireless hand motion controlled robotic arm using flex sensors

In today's world, in almost all industries, much of the work is performed by robots or robotic arms with varying degrees of freedom (DOF) as necessary. The aim of this study is to adjust the perception of remote controls for manually controlled robotic-arm operation. This paper offers a way of thinking and a way to eradicate the keys, joysticks and replace them with some of the more intuitive strategy that is to operate the full robotic arm by hand movements operators. The robotic arm is constructed in such a way that it consists of two movable fingers and other movement, which is, a spreading elbow and the up down movement. The robotic arm is designed to mimic the motions of human hands using a hand glove. The hand glove consists of 3 flex sensors for controlling the motions of the finger, the elbow, and other movements. Servo motors are the actuators used by the robotic arm. The proposed electronics device recognizes a basic hand gesture that will be made in real lifetime and will relay valued signals wirelessly through the RF module.

A new species of the genus Gaucha Mello-Leito, 1924 from Minas Gerais, Brazil (Solifugae, Mummuciidae).

A new sun-spider species of the ibirapemussu species-group of the genus Gaucha is described based on males and a female collected in Southeastern Brazil. The newly described species can be readily distinguished from its congeners by the reduction of the cheliceral fixed finger, distal tooth (FD), closely positioned and smaller than the medial tooth (FM); the presence of cheliceral fixed finger profondal subproximal (PFSP) and retrofondal submedial (RFSM) teeth; and by the cheliceral movable finger, medial tooth (MM) well developed, larger than submedial tooth (MSM) and smaller than proximal tooth (MP). This is the thirteenth described species in the genus Gaucha, all known from South America.

Two new species of Macrobrachium Spence Bate (Decapoda: Palaemonidae) from Ayeyarwady River, Myanmar with a note on Macrobrachium lamarrei (H. Milne Edwards 1837)

Two new species of the genus Macrobrachium Spence Bate have been described from near Mandalay of Ayeyarwady (Irrawaddy) River, Myanmar (22°2′37″N; 96°2′37″E). Macrobrachium univmandalay sp. nov. is closely related to Macrobrachium spinosum Cai & Ng, 2002 and Macrobrachium yui Holthuis, 1950 and is characterized by the presence of 10–12 dorsal teeth of which 3–4 post-orbital, first tooth at about 1/4th of anterior carapace; second chelate legs are dissimilar in size and shape in which carpus of major leg distinctly shorter than palm, cutting edges of fingers with 2 large and 2–3 smaller denticles at proximal part and without denticles on the distal half. Minor leg in which merus longer than carpus and palm, carpus shorter than palm as well as fingers and fingers without denticles in the cutting edges. M. spinosum and M. yui differ from this species in all these characters above.Macrobrachium ayeyarwadiense sp. nov. shows close affinity with Macrobrachium horstii de Man, 1892 and M. spinosum and can be easily separated on the basis of difference in characters of rostrum, position and arrangement of teeth on upper and lower margins, position of first dorsal tooth, distance between post-orbital edge and first dorsal tooth and its relation to rostrum length, length of antennular peduncle in relation to post-orbital carapace, shape and structure of 2nd cheliped, nature, size and arrangement of spines on outer and inner margins of ischium, merus, carpus, palm and fingers and nature of denticles on cutting edges of major and minor legs. The species can at once be identified on the absence of tubercles at distal half beyond larger denticles on fingers, convex nature of merus, carpus and disposition of spines on them, swollen palm and curved nature of movable finger and crossed nature of fingers distally of major 2nd peraeopod. Nature of long stiff setae on inner side of ischium, merus and carpus of major cheliped is characteristic to the species. Minor 2nd cheliped is also species specific in which the fingers are slender and curved so that a wide gap exists when closed. A note on Macrobrachium lamarrei (H. Milne Edwards 1937) is also given in the text.

First record of the symbiotic palaemonid shrimp Hamodactylus boschmai Holthuis, 1952 (Decapoda, Caridea) from Korea

Abstract Here, the symbiotic palaemonid shrimp Hamodactylus boschmai is recorded from Korean waters for the first time, based on specimens collected from different invertebrate hosts by trimix diving at depths of between 45 and 60 m in Jejudo Island. This species can readily be distinguished from its congeners by the presence of a distinct supraorbital tooth, the proximal segment of the antennular peduncle having a single tooth on the distolateral margin, the presence of a denticulate lamina along the entire cutting edge of the fingers of the first pereiopod chela, and the chela of the second pereiopods having a strongly hooked tip on the movable finger. An illustrated description, colour photographs, and a comparison of partial mitochondrial cytochrome c oxidase subunit I gene sequences are provided.