The efficiency of an asynchronous flight muscle from a beetle

Abstract

SUMMARYMechanical power output and metabolic power input were measured from an asynchronous flight muscle, the basalar muscle of the beetle Cotinus mutabilis. Mechanical power output was determined using the work loop technique and metabolic power input by monitoring CO2 production or both CO2 production and O2 consumption. At 35°C, and with conditions that maximized power output (60 Hz sinusoidal strain, optimal muscle length and strain amplitude, 60 Hz stimulation frequency), the peak mechanical power output during a 10 s burst was approximately 140 W kg–1, the respiratory coefficient 0.83 and the muscle efficiency 14–16 %. The stimulus intensity used was the minimal required to achieve a maximal isometric tetanus. Increasing or decreasing the stimulus intensity from this level changed mechanical power output but not efficiency, indicating that the efficiency measurements were not contaminated by excitation of muscles adjacent to that from which the mechanical recordings were made. The CO2 produced during an isometric tetanus was approximately half that during a bout of similar stimulation but with imposed sinusoidal strain and work output, suggesting that up to 50 % of the energy input may go to muscle activation costs. Reducing the stimulus frequency to 30 Hz from its usual value of 60 Hz reduced mechanical power output but had no significant effect on efficiency. Increasing the frequency of the sinusoidal strain from 60 to 90 Hz reduced power output but not CO2 consumption; hence, there was a decline in efficiency. The respiratory coefficient was the same for 10 s and 30 s bursts of activity, suggesting that there was no major change in the fuel used over this time range.The mass-specific mechanical power output and the efficiency of the beetle muscle were each 2–3 times greater than values measured in previous studies, using similar techniques, from locust flight muscles, which are synchronous muscles. These results support the hypothesis that asynchronous flight muscles have evolved in several major insect taxa because they can provide greater power output and are more efficient than are synchronous muscles for operation at the high frequencies of insect flight.

High Energy and Power Density Peptidoglycan Muscles through Super‐Viscous Nanoconfined Water

“…where R i is the ideal gas constant (8.314 J K −1 mol −1 ), T is the temperature (298.15 K), n is moles of exchanged water molecules between 5% RH and 90% RH, and a 1 and a 2 are activities of water vapor at 90% RH and 5% RH, respectively. We estimated cortex PG and cell wall PG's energy conversion efficiencies to be 35.0% and 66.8%, respectively, which are comparable to the efficiency of [38] graphene oxide/polypyrrole (GO/PPy) bilayer actuators, [39] sheath-run artificial muscles (SRAM), [4] graphdiyne actuators, [40] insect muscles (In muscle), [58] and mammalian muscles (Ma muscle) (Table S2, Supporting Information). [37] Table 1.…”

“…Error bars represent standard errors calculated from five measurements. h) Energy conversion efficiencies of cortex PG, cell wall PG, and other actuators/muscles, including cyclic olefin copolymer elastomer‐polyethylene (COCe‐PE), [ 38 ] graphene oxide/polypyrrole (GO/PPy) bilayer actuators, [ 39 ] sheath‐run artificial muscles (SRAM), [ 4 ] graphdiyne actuators, [ 40 ] insect muscles (In muscle), [ 58 ] and mammalian muscles (Ma muscle) (Table S2 , Supporting Information). [ 37 ]…”

Asynchronous and Self‐Adaptive Flight Assembly via Electrostatic Actuation of Flapping Wings

“…[ 27,28,80,81 ] For miniaturized flying robots with mass in the range of 80–300 mg driven by piezoelectric and electromagnetic means, the power consumptions are generally less than 1.2 W with efficiencies less than 10%. [ 1,23,25,82,83 ] In contrast, the power consumptions for natural flying insects also gradually decrease with respect to mass, whereas their efficiencies are in the range of 10–20% even if the mass decreases to below 1 mg. [ 31,61,63,84–87 ] This work shows the ground testing prototypes driving by electrostatic actuation can have masses in the range of 2.9–25.4 mg with measured input power of 0.0286–0.323 mW resulting high efficiencies in the range of 36.0–38.5%. As a result, the remarkably low power consumption makes our devices have the potential to be powered onboard by solar cells, [ 89 ] in favor of miniaturizations for future flying insects with untethered, long‐endurance, and autonomous flights.…”

“…[29,30] In contrast, the asynchronous flight muscles maintain the contraction and relaxation activities based on the stretchactivation mechanism, which is a self-oscillatory mechanism [15] under the stimulation of one neural impulse. [13,31] The flapping behavior of wings in each cycle depends on the inherent characteristics of the muscle-wing structure rather than the neural system. Figure 1a,b shows the natural asynchronous flight muscles with 1:N myogenic action and four-steps electrophysiology procedures.…”

The cibarial pump of the xylem-feeding froghopperPhilaenus spumariusproduces negative pressures exceeding 1 MPa

“…With minimal change in CDM contraction velocity, as indicated by relatively constant f pump and Q values, the small difference between these values is unsurprising. While the efficiency of synchronous and asynchronous insect flight muscle has been determined to lie between 10 to 16% [28,29], to our knowledge there are no published values for insect skeletal (non-flight) muscle efficiency. However, in vitro estimates of vertebrate locomotory muscle give maximum peak efficiencies of 25% without pre-stretching the muscle, and up to 50% if the muscle is pre-stretched [30].…”