Polymer investment molding: Method for fabricating hollow, microscale parts

Lippmann, Julian M.; Geiger, Emil J.; Pisano, Albert P.

doi:10.1016/j.sna.2006.05.009

Cited by 37 publications

(22 citation statements)

References 16 publications

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“…As these devices approach production, the ability to inexpensively fabricate these surfaces is becoming increasingly important (Lippmann et al, 2007). Injection molding these structured surfaces offers the potential to provide cost effective alternative fabrication methods to MEMS technologies (Chien, 2006;Ito et al, 2006;Murakami et al, 2006;Su et al, 2004;Yokoi et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Vacuum Venting for Micro-injection Molding

Yoon

Padmanabha

Cha

et al. 2011

International Polymer Processing

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While the effect of vacuum venting has been reported for injection molding of micro and nanoscale features, the limited research has produced conflicting results. To clarify the positive effect of vacuum venting on replication of microscale features, this work focused on the interactions between vacuum venting and (1) feature size, (2) material type in terms of melt viscosity and wettability, and (3) injection velocity and mold temperature. A metal-polymer hybrid tooling with a range of positive microscale features was employed to mold polystyrene and polymethylmethacrylate parts. Overall, vacuum venting always effective in feature definition (sharpness of edges) enhancement, but provided increases in depth ratio that depended on material (melt viscosity and wettability) and processing conditions (i. e., injection velocity, and mold temperature).

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Section: Introductionmentioning

confidence: 99%

Evaluation of Vacuum Venting for Micro-injection Molding

Yoon

Padmanabha

Cha

et al. 2011

International Polymer Processing

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“…As a substantial number of biodegradable microneedles are classed polymers, a supposedly third fabrication technique called investment moulding has been used suitably for hollow non-biodegradable polymers in which a drug solution flows through the hollow part of the microneedles into the skin (Lippmann 2007;Lippmann and Pisano 2006). Melt injection processes in investment moulding are suitable for thermoplastics because in adaptation of micromoulding, very high shear is required to allow for lower viscous melt and low resistant flow but heat generation can cause degradation of the drug formulation (Zhao et al 2003).…”

Section: Fabrication Of Biodegradable Microneedles From Mouldsmentioning

confidence: 99%

Potential of biodegradable microneedles as a transdermal delivery vehicle for lidocaine

Nayak

Das

2013

Biotechnol Lett

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There has been an increasing interest in applying biotechnology in formulating and characterising new and innovative drug delivery methods, e.g., drug-loaded biodegradable microneedles within the area of transdermal delivery technology. Recently, microneedles have been proposed for use in pain management, e.g., post-operative pain management through delivery of a local anaesthetic, namely, lidocaine. Lidocaine is a fairly common, marketed prescription-based local anaesthetic pharmaceutical, applied for relieving localised pain and lidocaine-loaded microneedles have been explored. The purpose of this review is to evaluate the properties of biodegradable polymers that may allow the preparation of microneedle systems, methods of preparing them and pharmacokinetic conditions in considering the potential use of lidocaine for delivery through the skin.

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“…Fourth and finally, the fabrication process should rely only on inexpensive methods such as micromolding, ideally rejecting complicated two-piece molds or fragile demoldable cores. (Davis et al 2005; Kim and Colton 2005; Xu et al 2005; Lippmann et al 2007; Matteucci et al 2009; Burton et al 2011). A microneedle meeting these criteria could easily insert into skin, inject at a moderate pressure to reduce patient pain, and compete on costs with needles and syringes.…”

Section: Introductionmentioning

confidence: 99%

“…To simplify intradermal delivery, we and others have fabricated hollow microneedles that target drug delivery into the skin with needles that are shorter than the thickness of the skin (Kim et al 2004; Davis et al 2005; Moon and Lee 2005; Stoeber and Liepmann 2005; Pérennès et al 2006; Alarcon et al 2007; Lippmann et al 2007; Ovsianikov et al 2007; Roxhed et al 2007; Burton et al 2011; Li et al 2012). These devices are expected to reliably target injections into the skin, even by healthcare professionals without special training on their use (Laurent et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Hollow microneedles for intradermal injection fabricated by sacrificial micromolding and selective electrodeposition

Norman

Choi

Tong

et al. 2012

Biomed Microdevices

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Limitations with standard intradermal injections have created a clinical need for an alternative, low-cost injection device. In this study, we designed a hollow metal microneedle for reliable intradermal injection and developed a high-throughput micromolding process to produce metal microneedles with complex geometries. To fabricate the microneedles, we laser-ablated a 70 μm × 70 μm square cavity near the tip of poly(lactic acid-co-glyoclic acid) (PLGA) microneedles. The master structure was a template for multiple micromolded PLGA replicas. Each replica was sputtered with a gold seed layer with minimal gold deposited in the cavity due to masking effects. In this way, nickel was electrodeposited selectively outside of the cavity, after which the polymer replica was dissolved to produce a hollow metal microneedle. Force-displacement tests showed the microneedles, with 12 μm thick electrodeposition, could penetrate skin with an insertion force 9 times less than their axial failure force. We injected fluid with the microneedles into pig skin in vitro and hairless guinea pig skin in vivo. The injections targeted 90% of the material within the skin with minimal leakage onto the skin surface. We conclude that hollow microneedles made by this simple microfabrication method can achieve targeted intradermal injection.

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Polymer investment molding: Method for fabricating hollow, microscale parts

Cited by 37 publications

References 16 publications

Evaluation of Vacuum Venting for Micro-injection Molding

Evaluation of Vacuum Venting for Micro-injection Molding

Potential of biodegradable microneedles as a transdermal delivery vehicle for lidocaine

Hollow microneedles for intradermal injection fabricated by sacrificial micromolding and selective electrodeposition

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