Investigation of the Effect of Spin Crossover on the Static and Dynamic Properties of MEMS Microcantilevers Coated with Nanocomposite Films of [Fe(Htrz)2(trz)](BF4)@P(VDF-TrFE)

Abstract

We used a spray-coating process to cover silicon microcantilevers with ca. 33 wt% [Fe(Htrz)2(trz)](BF4)@P(VDF70-TrFE30) nanocomposite thin films of 1500 nm thickness. The bilayer cantilevers were then used to investigate the thermomechanical properties of the composites through a combined static and dynamic flexural analysis. The out-of-plane flexural resonance frequencies were used to assess the Young’s modulus of the spray-coated films (3.2 GPa). Then, the quasi-static flexural bending data allowed us to extract the actuation strain (1.3%) and an actuation stress (7.7 MPa) associated with the spin transition in the composite.

Thermal hysteresis of stress and strain in spin-crossover@polymer composites: towards a rational design of actuator devices

“…[4][5][6] This huge transformation strain has motivated research to harness different forms of energy into useful mechanical work via the SCO phenomenon, with potential applications in robotic, biomedical and nano-technologies. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] In this context, embedding SCO particles into polymer matrices provides a versatile means for exploiting this mechanical strain in actuating, 7,8,[11][12][13][15][16][17]19,20,22,23 sensing 9,10,21 and energy harvesting 14,18 devices. Indeed, a polymer matrix allows for convenient processing the SCO material, such as dispersions of microcrystals, nanoparticles, nanorods or molecules, to obtain functional objects with arbitrary shapes at different size scales, including both macroscopic and micro/nanoscale devices.…”

“…4–6 This huge transformation strain has motivated research to harness different forms of energy into useful mechanical work via the SCO phenomenon, with potential applications in robotic, biomedical and nano-technologies. 7–24…”

“…In this context, embedding SCO particles into polymer matrices provides a versatile means for exploiting this mechanical strain in actuating, 7,8,11–13,15–17,19,20,22,23 sensing 9,10,21 and energy harvesting 14,18 devices. Indeed, a polymer matrix allows for convenient processing the SCO material, such as dispersions of microcrystals, nanoparticles, nanorods or molecules, to obtain functional objects with arbitrary shapes at different size scales, including both macroscopic and micro/nanoscale devices.…”

The crystallinity and piezoelectric properties of spray-coated films of P(VDF70-TrFE30): effects of film thickness and spin-crossover nanofillers

“…28 This strain can be then used for mechanical actuation purposes. 29 In particular, SCO@P(VDF-TrFE) composites were used to actuate MEMS 30 or other types of mechanical systems, 31 but the strain can also be coupled to the piezoelectric properties of the P(VDF-TrFE) matrix to provide original (thermo-electrical) product properties. 24,25 In the present work, we charged the polymer matrix with a 33 vol% nanocrystalline SCO compound with the chemical formula [Fe(Htrz) 2.05 (trz) 0.75 (NH 2 trz) 0.2 ](BF 4 ) 1.25 (trz = 1,2,4-triazolato).…”

Tunable mechanical properties of [Fe(pyrazine){Au(CN)2}2]–PVDF composite films with spin transitions

“…22,23 Various devices, mainly consisting of bilayer structures, have been constructed and investigated for their actuating properties in response to the spin-state change in coordination complexes, notably this actuating performance is directly related to the elastic parameters of active materials. [24][25][26] Here we report on a fabrication of composite films based on [Fe(pz){Au(CN) 2 } 2 ] and poly(vinylidene fluoride) (PVDF). As the spin transition of the obtained films can be readily exploited for actuating purposes, their elastic properties were studied.…”