Towards artificial proprioception from artificial muscles constituted by self-sensing multi-step electrochemical macromolecular motors

Highlights

• Under electrochemical reaction conducting polymers act as model materials of the reactions originating biological functions and multifunctionality.

• One motor and several sensors (mechanical, thermal and chemical) work in electrochemical artificial muscles replicating muscular multifunctionality.

• The reaction energy adapts to and senses any energetic (mechanical, thermal and chemical) perturbation.

• The basic equation of the electrochemical kinetics describes both, the actuating and the sensing properties (self-awareness) opening the way towards proprioceptive robots.

• The study of model materials provides information about: muscle tiredness, ectotherm muscles, muscular asymmetric actuation or nervous pulse generation from the muscle.

Abstracts

Many life functions emerge from bio-electro-chemical reactions involving macromolecular motors, exchange of ions and water triggered by nervous (electric) pulses. Muscles are natural electro-chemical motors sensing by themselves the working physical and chemical conditions: multi-sensing motors. Here we review how by electrochemical reactions conducting polymers and other electroactive materials give artificial muscles replicating both, the dense gel composition and multi-functionality of the muscle’ cell. They are Faradaic devices: the flowing current controls the movement rate and the consumed charge defines the displacement amplitude. The consumed energy (or any of its components: muscle potential, charge or current) responds to, adapts to and senses, at any time, the working mechanical, chemical, thermal and electrical conditions: multi-sensing or self-awareness. The equations describing self-awareness were attained from the basic chemical and electrochemical kinetics and checked by experimental results. Translated to Biology the sensing equations can describe: muscle's fatigue, the energy that coldblooded animals can extract from the ambient, why muscles only work by contraction, how muscles generate each nervous pulses and how many packages of quantitative information they translate to the brain. Only two connecting wires include, at any time, actuating and sensing signals: the system computer-potentiostat/two wires/artificial muscle replicates brain/motor neuron-sensory neuron/muscle. That multi-functionality is originated by only one reaction driving the cooperative actuation multi-sensing and multi-step electrochemical macromolecular motors. None similar multi-sensing motor exists in nowadays technology. The way is open to develop self-awareness devices and proprioceptive robots.