Design, Fabrication and Testing of a Polymer Composite Based Hard-Magnetic Mirror for Biomedical Scanning Applications

• Published in: Journal of the Electrochemical Society Vol. 161; no. 2; pp. B3006 - B3013
• Main Authors: Pallapa, M., Yeow, J. T. W.
• Format: Journal Article
• Language: English
• Published: The Electrochemical Society 01.01.2014
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/2.001402jes

In this work, we combine the advantages of hard magnets, polydimethylsiloxane (PDMS) micro-molding and printed circuit board planar coils to propose an electromagnetically actuated bidirectional scanner with potential applications in bio-medical scanning. The proposed bidirectional scanner (4 mm × 4 mm × 250 μm) is fabricated by micromolding an isotropic Nd-Fe-B micropowder (MQFP-12-5) doped in a PDMS matrix at 80% weight percentage and magnetized using a standard dipole electromagnet. A reflective gold layer of 100 nm is evaporated onto the polymer composite structure. A maximum magnetic field of 20 mT is measured for the polymer magnetic mirror. Rectangular planar coils (trace width and spacing: 254 μm; 10 turns) are employed to actuate the bidirectional scanner electromagnetically by Lorentz force. Actuation in both static and dynamic excitation modes is tested. Power consumption at a maximum rotational angle (15 degrees - optical) is one watt at 40 Hz resonant frequency. Initial surface roughness of the mirror (165 nm) and radius of curvature (75 mm) has been addressed by depositing a thin layer of PDMS, resulting in 66.24 nm surface roughness and 321.37 mm overall radius of curvature after integration. Major advantages of the proposed bidirectional scanner include low fabrication cost, low input voltage and large actuator displacement compared to existing electrostatic scanners.