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Recent progress of dissolving microneedles opens up a great potential for the utilisation of microneedles in a wide range of applications. However, the commercialisation of dissolving microneedles requires mass production of microneedle masters and moulds. In this work, a simple, low-cost and high-throughput fabrication method of high-density microneedle masters is presented. The high-density microneedle masters were fabricated by first machining an aluminium workpiece to form high-density rectangular column arrays using wire-cut electrode discharge machining. Subsequently, the rectangular column arrays were subjected to a chemical etching under a mass-transport limited condition resulting in the formation of conical-shaped microneedle masters without the need of etch mask. For demonstration, the fabricated microneedle masters were used as a template for the fabrication of an inverse polymer mould and subsequently the polymer mould was used for the fabrication of silk microneedles. The proposed method offers a simple, low cost and high throughput means for the mass production of high-density microneedle masters towards the commercialisation of dissolving microneedles.

This paper presents an oscillating drum granulator prototype for cassava pearl. Effects of filling degree and oscillating speed on cassava pearl granulation were investigated. A stainless steel drum granulator with 50 cm diameter and 16 cm length was developed. The stainless steel joints with a cotton-transmitting belt were used to connect the drum to an oscillator arm to simulate the flexibility of a traditional cloth cradle granulator. The filling degree and oscillating speed were varied from 1, 2 and 3 kg and from 87 and 100 rpm, respectively. During granulation, samples were taken at 4, 8, 12 and 16 minutes to determine the particle size distribution, mass mean diameter, granule density, hardness and sphericity. The results indicated that both the filling degree and oscillating speed played an important role on cassava pearl granulation. The filling degree of 3 kg and oscillating speed of 100 rpm was suggested since it yielded similar properties of cassava pearls to those obtained from the traditional process. This prototype granulator could successfully produce 2.4-mm pearls with comparable characteristics to the standards. Comparing to a traditional granulator, the oscillating drum granulator is easier to clean and more GMP compliant.

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