Site‐Specific Selective Bending of Actuators using Radio Frequency Heating

Abstract

Actuators have gained considerable attention in recent years due to their wide range of applications, such as soft robotics, [1][2][3][4][5][6] artificial muscles, [7][8][9] drug delivery, [10] micromanipulation systems, [11,12] and switches. [13][14][15] Actuators convert external stimuli, such as temperature (including electrothermal [2,6,16] or photothermal [17,18] ), pressure, [19] and chemical inputs, [20] into mechanical energy. Actuators are useful when motion is needed in a place where humans cannot reach, such as hazardous or microscale environments. However, major challenges for actuators include the ability to move without direct connection to a power source and the ability to have site-specific actuation.Generally, for thermal actuators, two heat sources have been used as input: direct current (DC) power and photothermal from light. DC-based actuators have simple fabrication steps, [8,17] but actuators need to be connected to the source by wires, which limit their movement. Photothermal actuators can solve this physical limitation by using light to locally trigger heating. [5,18,21] These actuators also have advantages including price, safety, easy control, and fast response. Wang et al. used photothermal actuator as a propeller by continuously exposing the on/off cycles of infrared light at one end of the actuator. [5] In addition, liquid crystalline elastomers can be used in photothermal actuation; in the study by Zuo et al., three wavelengths were used to trigger the selective bending of actuators with three different dyes. [22] Radio frequency (RF) heating of nanomaterials is a noncontact heating method, [23] which can be used as heat source for actuation. Noncontact heating occurs due to the coupling of an induced electrical field with susceptors embedded in the material. Our group has previously demonstrated that certain nanomaterials act as RF susceptors, such that they will heat rapidly in response to an applied field; this allows for volumetric heating in a composite with susceptor fillers, such as carbon nanotubes (CNTs), laserinduced graphene (LIG), MXenes, [24] and carbon black. [23,[25][26][27] This phenomenon has been applied to a range of manufacturing applications such as welding of polymer sheets, [28] curing of epoxy nanocomposites [23] or preceramic polymer composites, [29] and screening of CNT circuits. [25,27] We have shown that the sample does not have to be directly connected to the power source, and it can heat the carbon nanomaterials at different applicator configurations (parallel plate and fringing field). [23] Despite the advantages that RF heating holds, the study of nanomaterial composite actuators using noncontact RF heating as a heat source has not been explored yet. RF heating behavior can be used as a means to not only locally trigger actuation but also perform site-specific actuation by controlling frequency.

Laser-Induced Graphene Based Flexible Electronic Devices

“…LIG-based electrochemical sensors show their potential in detecting the contents of organic (i.e., glucose and dopamine) and inorganic matter (i.e., NO 2 and H 2 O 2 ) [ 9 , 11 , 24 , 26 , 28 , 66 , 69 , 74 , 84 , 85 , 86 , 87 , 88 ]. As shown in Figure 5 a, the sensor was introduced to measure the blood glucose (BG) and the sweat glucose (SG) concentrations before and after meal [ 106 ].…”

Rapid Synthesis of Patterned Silicon Carbide Coatings Using Laser‐Induced Pyrolysis and Crystallization of Polycarbosilane

“…RF heating of materials has shown great potential for a range of applications including welding of polymers, [ 36 ] composite manufacturing, [ 37 ] chemical reaction engineering, [ 38 ] and actuation. [ 39 ] Figure shows RF heating of LISiC. A noncontact fringing‐field applicator fabricated in‐house (Figure 6a) was used to heat the material, which was monitored using a thermal camera.…”

Low Voltage and Low Temperature Soft Electrothermal Actuator Based on PE/Graphite Bilayer Film

“…At the same time, it also proved the stability of the intermediate adhesive in terms of bonding the two layers of film. SACNS/PDMS 30×6×0.77 mm 100 40 [9] RGO/PDMS 8×2×0.12 mm 35 80 12 [3] Graphite/PI 270 216 12.5 [18] RGO/ PE 50 60 [19] GO/RGO 120 80 7 [14] CFF/EVA 60×5×0.35 100 10 [8] Graphite/PI 40×5×0.14 mm 248.6 300 6 [12] PI/Paper/PDA-Zn2+/(M/G) 40×15 mm 120 10 [13] PDMS/carbon tape 160 20(W) [15] PTFE/MXene/PI 30×5 mm 120 100 6…”

“…The electrothermal control method is different from the high-voltage driving of an electronic electroactive polymer (EAP), as the ionic EAP needs to function in the electrolyte. Its low-voltage operation, without the limitation of the need for a specific environment, and easy operation make it widely used in human-computer interaction, [8] optics, [9] DOI: 10.1002/mame.202100690 sensing, [10][11][12] smart switches, [13] electromagnetic shielding, [14][15][16] soft mechanical grasper, [17] and various other fields.…”

“…At present, most soft electrothermal actuators need to reach a very high temperature to generate actuation. [3,4,8,10,[12][13][14][15] For example, the Polyimide (PI)/graphite nanoplate composite film researched by Wang [3] achieved a bending angle of 270°under a driving voltage 3-48 V, but the maximum angle could be reached only once the temperature had reached nearly 200 °C. The spongy graphene/ Polydimethylsiloxane (PDMS) composite membrane studied by Hu et al [4] also needed to reach 100 °C for actuation.…”