Surface microstructuring of biocompatible bone analogue material HAPEX using LIGA technique and embossing

Andreas Schneider; Susan Rea; Ejaz Huq; William Bonfield

doi:10.1117/12.498779

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24 April 2003 Surface microstructuring of biocompatible bone analogue material HAPEX using LIGA technique and embossing

Andreas Schneider, Susan Rea, Ejaz Huq, William Bonfield

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Proceedings Volume 5116, Smart Sensors, Actuators, and MEMS; (2003) https://doi.org/10.1117/12.498779
Event: Microtechnologies for the New Millennium 2003, 2003, Maspalomas, Gran Canaria, Canary Islands, Spain

Abstract

HAPEX is an artificial bone analogue composite based on hydroxyapatite and polyethylene, which can be applied for growth of bone cells. Due to its biocompatibility and favourable mechanical properties, HAPEX is used for orthopaedic implants like tympanic (middle ear) bones. The morphology of HAPEX surfaces is of high interest and it is believed that surface structuring on a micron scale might improve the growth conditions for bone cells. A new and simple approach for the microstructuring of HAPEX surfaces has been investigated using LIGA technique. LIGA is a combination of several processes, in particular lithography, electroplating and forming/moulding. For HAPEX surface structuring, arrays of dots, grids and lines with typical lateral dimension ranging from 5 μm to 50 μm were created on a chromium photomask and the patterns were transferred into thick SU-8 photoresist (structure height > 10 μm) by UV lithography. Subsequently, the SU-8 structures served as moulds for electroplating nickel on Si wafers and nickel substrates. The final nickel microstructures were used as embossing master for the HAPEX material. Embossing was carried out using a conventional press (> 500 hPa) with the facility to heat the master and the HAPEX. The temperature ranged from ambient to a few degrees above glass transition temperature (T_g) of HAPEX. The paper will include details of the fabrication process and process tolerances in lateral and vertical directions. Data obtained are correlated to the temperature used during embossing.

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Andreas Schneider, Susan Rea, Ejaz Huq, and William Bonfield "Surface microstructuring of biocompatible bone analogue material HAPEX using LIGA technique and embossing", Proc. SPIE 5116, Smart Sensors, Actuators, and MEMS, (24 April 2003); https://doi.org/10.1117/12.498779

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