Multilayered Microcoils for Microactuators and Characterization of Their Operational Limits in Body-Like Environments

Abstract

Multilayered microcoils are of great importance for the development of advanced electromagnetic microactuators and especially important to develop high sensitivity microsensors and magnetic field neural stimulators for medical applications. A clean room-free procedure for manufacturing multilayered micrometric coils is presented in this work. The production of miniaturized multilayered coils from tens to hundreds of micrometres long is demonstrated. The microcoils have outer diameters ranging between 150 and 300 µm, arrangements of up to 5 consecutive layers, and an average fill factor of 85%. This means 3 times smaller diameters than the smallest diameter ever achieved by winding techniques while keeping a high fill factor and a large number of layers. Such small and highly performant microcoils have never been demonstrated neither by winding processes nor epitaxial growth techniques. These microcoils were tested inside different human body-like environments. Maximum current density vs. temperature was measured in air, fat tissue, muscle tissue and simulated body fluid at 36 °C. A maximum current density of 3600 A/m 2 has been measured before coil failure. Experiments demonstrated that current densities up to 610 A/m 2 can safely be supplied to coils without risk of harm to internal tissues. These counterintuitive values are orders of magnitude larger than typical current densities used in macroscale actuators windings. 1

Model‐based systems engineering approach to the study of electromagnetic interference and compatibility in wireless powered microelectromechanical systems

“…Exploring high torque density micromotors for micro-robotic joints is one of the main objectives of H2020 UWIPOM2 project. See the papers of Villalba-Alumbreros et al 70 and Diez-Jimenez et al 71 This project seeks to develop a micrometric-size wireless powered micromotor. The micromotor will be wireless powered through gigahertz electromagnetic waves, thus providing infinite autonomy to any tool.…”

“…See the papers of Villalba‐Alumbreros et al 70 . and Diez‐Jimenez et al 71 . This project seeks to develop a micrometric‐size wireless powered micromotor.…”

Miniaturized High Gain Flexible Spiral Antenna Tested in Human-Like Tissues

“…The antenna was manufactured following the same winding technique as the microcoils shown in reference [27]. The antenna prototype is shown in Figure 4 a).…”

Microfabrication of Sm2Co17 micromagnets for MEMS and micromotors using ultrashort pulsed hydro laser micromilling process

“…Not only small magnets are used, structures of magnets with micrometric features, specific geometries, or magnetic multipole pattern distributions [23] are also required in MEMS applications [24]. The combined use of permanent magnets, micrometric high-quality ferromagnetic parts [25] and microinductors [26][27] makes possible to achieve high specific power, torque and force in MEMS devices.…”