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Micro-molding

Next, micro-molding of PLA is investigated. The schematic diagram of compression molding to
produce the 3D micro structures of PLA micro needle is shown in Fig. 7. First, PLA is re-flowed at
above its melting temperature, and is put onto a heated mold (200°C, 3 min.). Second, pressure is
applied to the silicon cavity and PLA (14 MPa, 1 min.). Third, PLA is etched back to the level of the
silicon surface by oxygen plasma gas. Finally, the micro needle is taken away from the mold by using
an adhesive tape. Figure 8 shows the fabricated PLA micro needle. The size of needle is as follows:
length is 1000 um, height is 64 um and width is 127 ixm.

J3- Pressure force
Heater (200*0

Silicon PLA
Heater (200*0
Figure 7: Mechanism of compression molding Figure 8: SEM image of fabricated micro needle

CONCLUSIONS

A micro needle made by biodegradable polymer is fabricated, which has jagged shape like mosquito's
needle. The summary is as follows:
1) The compatibility characteristics of PLA to wet etching solutions and dry etching gases are
investigated. PLA has resistively against H3PO4, HF solutions and CHF3 plasma gas.
2) The uniform jagged groove of cavity for the micro needle is fabricated by new method of 2 step
anisotropic wet etching by KOH and TMAH solutions. Compression molding method is applied
and a jagged needle is surely released.

ACKNOWLEDGEMENT
This work was mainly supported by JSPS (Japan Society for the Promotion of Science).KAKENHI
(16310103). This work was also partially supported by MEXT (Ministry of Education, Culture, Sports,
Science and Technology). KAKENHI (17656090), "High-Tech Research Center" Project for Private
Universities: Matching Fund Subsidy from MEXT, 2000-2004 and 2005-2009, the Kansai University
Special Research Fund, 2004 and 2005.

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