Bio-inspired Artificial Muscle Research Articles

Cold-induced shape memory hydrogels for strong and programmable artificial muscles

Thermo-responsive shape memory hydrogels generally achieve shape fixation at low temperatures, and shape recovery at high temperatures. However, these hydro-gels usually suffer from poor mechanical properties. Herein, we present a unique poly(acrylic acid)/calcium acetate shape memory hydrogel with cold-induced shape recovery performances as ultrastrong artificial muscles. Since the acetate groups could form aggregate at high temperatures and thus induce the association of the hydrogel network, the hydrogel can be fixed into a temporary shape upon heating and recover to its original shape in a cold environment. Moreover, a programmable shape recovery process is realized by adjusting the shape fixing time. In addition, the unique shape memory process enables the application demonstration as bio-inspired artificial muscles with an ultrahigh work density of 45.2 kJ m−3, higher than that of biological muscles (∼8 kJ m−3).

One Soft Step: Bio-Inspired Artificial Muscle Mechanisms for Space Applications.

Soft robots, devices with deformable bodies and powered by soft actuators, may fill a hitherto unexplored niche in outer space. All space-bound payloads are heavily limited in terms of mass and volume, due to the cost of launch and the size of spacecraft. Being constructed from stretchable materials allows many possibilities for compacting soft robots for launch and later deploying into a much larger volume, through folding, rolling, and inflation. This morphability can also be beneficial for adapting to operation in different environments, providing versatility, and robustness. To be truly soft, a robot must be powered by soft actuators. Dielectric elastomer transducers (DETs) offer many advantages as artificial muscles. They are lightweight, have a high work density, and are capable of artificial proprioception. Taking inspiration from nature, in particular the starfish podia, we present here bio-inspired inflatable DET actuators powering low-mass robots capable of performing complex motion that can be compacted to a fraction of their operating size.

Towards bio-inspired artificial muscle: a mechanism based on electro-osmotic flow simulated using dissipative particle dynamics

One of the unresolved issues in physiology is how exactly myosin moves in a filament as the smallest responsible organ for contracting of a natural muscle. In this research, inspired by nature, a model is presented consisting of DPD (dissipative particle dynamics) particles driven by electro-osmotic flow (EOF) in micro channel that a thin movable impermeable polymer membrane has been attached across channel width, thus momentum of fluid can directly transfer to myosin stem. At the first, by validation of electro-osmotic flow in micro channel in different conditions with accuracy of less than 10 percentage error compared to analytical results, the DPD results have been developed to displacement of an impermeable polymer membrane in EOF. It has been shown that by the presence of electric field of 250 V/m and Zeta potential − 25 mV and the dimensionless ratio of the channel width to the thickness of the electric double layer or kH = 8, about 15% displacement in 8 s time will be obtained compared to channel width. The influential parameters on the displacement of the polymer membrane from DPD particles in EOF such as changes in electric field, ion concentration, zeta potential effect, polymer material and the amount of membrane elasticity have been investigated which in each cases, the radius of gyration and auto correlation velocity of different polymer membrane cases have been compared together. This simulation method in addition of probably helping understand natural myosin displacement mechanism, can be extended to design the contraction of an artificial muscle tissue close to nature.

Forecast for Artificial Muscle Tremor Behavior Based on Dynamic Additional Grey Catastrophe Prediction

Recently, bio-inspired artificial muscles based on ionic polymers have shown a bright perspective in engineering and medical research, but the inherent tremor behavior can cause instability of output response. In this paper, dynamic additional grey catastrophe prediction (DAGCP) is proposed to forecast the occurrence time of tremor behavior, providing adequate preparation time for the suppression of the chitosan-based artificial muscles. DAGCP constructs various dimensions of time subsequence models under different starting points based on the threshold of tremor occurrence times and peak-to-peak values in unit time. Next, the appropriate subsequence is selected according to grey correlation degree and prediction accuracy, then it is updated with the newly generated values to achieve a real-time forecast of forthcoming tremor time. Compared with conventional grey catastrophe prediction (GCP), the proposed method has the following advantages: (1) the degradation of prediction accuracy caused by the immobilization of original parameters is prevented; (2) the dynamic input, real-time update and gradual forecast of time sequence are incorporated into the model. The experiment results show that the novel DAGCP can predict forthcoming tremor time earlier and more accurately than the conventional GCP. The generation mechanism of tremor behavior is illustrated as well.

Characterisation and control of IPMC for use in bio-inspired actuators

This paper presents the development and design of a bio-inspired artificial muscle actuator. The proposed design uses ionic polymeric metallic composites (IPMC), which functions as the force generating source in the actuator. The relation between input voltage and position of the end point IPMC actuator was characterised experimentally. A mathematical model is developed and used in controlling the IPMC motion using a PID controller. The controller shows a good tracking of the reference signals sent to test the system. A real time control system is developed. Experimental results show that it exhibited good tracking with respect to the reference signals.

Characterisation and control of IPMC for use in bio-inspired actuators

This paper presents the development and design of a bio-inspired artificial muscle actuator. The proposed design uses ionic polymeric metallic composites (IPMC), which functions as the force generating source in the actuator. The relation between input voltage and position of the end point IPMC actuator was characterised experimentally. A mathematical model is developed and used in controlling the IPMC motion using a PID controller. The controller shows a good tracking of the reference signals sent to test the system. A real time control system is developed. Experimental results show that it exhibited good tracking with respect to the reference signals.

Bio-inspired Artificial Muscle Based on Chemical Sensors

In this work, we have investigated the modeling, design and fabrication of bio-inspired artificial muscle unit capable of contracting according to the directives sent in form of chemical messengers. This new technology has the potential to revolutionize current robotics, because it could permit a paradigm shift in robots: from electro-mechanical devices to electro-chemical devices. The bio-inspired artificial muscle will be based on basic contractile units coupled to electrochemical sensors, with the purpose of allowing adaptive and flexible control similar to that in animal locomotion. An artificial nerve termination, able to modify the chemical characteristics of the inner environment, will generate directives in form of chemical messengers. Electro-chemical sensors have been used in order to detect the presence of the chemical messengers and transform them into electronic signals to be used in conventional control electronics. This study has been focused on the development and optimization of sensing materials for inorganic ions such as hydrogen ions. Among various conducting polymers studied, polyaniline (PANI) has attracted much attention due to its unique and controllable chemical and electrical properties. PANI layer has been electrochemically deposited on the gold arrays surface by cyclic voltammetry. Preliminary experiments on PANI-modified sensors in order to obtain the better sensitivity as chemical sensing used in artificial muscle unit have been carried out. To allow diffusion of chemical messages, the system has been immersed in wet environment. Using this approach, we study the effective possibility to control, assessing the performance in terms of accuracy of the control of the contraction, the impact of the delay due to the transmission time of the chemicals, precision and stability of control.

Towards development of a bio-inspired artificial muscle using IPMC for potential applications in robotics

Biological muscle is an efficient actuator that has unique characteristics; such as flexibility, high specific power and lightweight. There is a real need to develop an artificial muscle which mimics the characteristics and functionality of the biological muscle. In this paper a new bio-inspired multi-segment muscle actuator model is presented using ionic polymeric metallic composites (IPMC). The contraction stage model of the actuator is derived and the force-length relation of the actuator shows that the actuator can produce a maximum total force of 0.12 N, and it can contract a total axial displacement of 12 mm/step.