Fig. 1. Fabrication process of Ni microneedle arrays

Fig. 2. Mask used for second lithography

Fig. 3. Microelectroforming process for thin photoresist silicon template

Fig. 4. Ni microneedle arrays after ultrasonic release

Fig. 5. Ni microneedle arrays after chemical release

Fig. 6. New mask used for second lithography

Fig. 7. Ni microneedle arrays after physical release

Fig. 8. SEM image of Ni microneedle tip

Fig. 9. Length and width at the base of the Ni microneedle arrays

Fig. 10. Statistics scatter plot of the Ni microneedle arrays size

Fig. 11. Deviation histogram of the actual position versus the designed position of the Ni microneedle arrays