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Pegasus deep reactive\u2010ion etching (DRIE) system, an advanced two\u2010step etching process has been developed for hollow microneedles in applications of transdermal blood sampling and drug delivery. Because of the different etching requirements of both narrow deep hollow and large open cavity, hollow etch and cavity etch steps have been achieved separately. This novel two\u2010step etching process is assisted with a bi\u2010layer etching mask. Results show that the etch rate of silicon during this hollow etch step was about 7.5 \u00b5m\/min and the etch rate of silicon during this cavity etch step was about 8\u201310 \u00b5m\/min, using the coil plasma etching power between 2.0 and 2.8\u00a0kW. Especially for the microneedle bores etch, the deeper it etched, the slower the etch rate was. 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