MOLDING MICRO SURFACE FEATURES
9/19/13 Here’s something that always causes a few eyebrows to be raised, and which exemplifies the progress that has been made in micro molding in recent months and years.
Micro molding per se is now obviously an established technology, and we at Micro Engineering Solutions have been involved with hundreds of successful projects with numerous OEMs over the years. But sometimes even we sit back and go “Wow!!”.
The picture you see with this blog is of a silicone microfluidic device with injection molded features that are 3 microns deep. 84 million such structures can fit onto a microscope slide. Until relatively recently, this would have been impossible, but now that we are able to create such tiny surface features with such accuracy and repeatability, the possibilities that are opened up across industry are endless.
Let’s start with the basics, however. Not everyone can manufacture parts with such micro surface features. To achieve such precision requires the combination of significant experience in micro molding, and an innate understanding of the specific contingencies that affect manufacturing at such a scale.
The key focus, quite obviously, is on tooling. Gate location, for example, can help to eliminate hesitation problems, where surface defects occur due to stagnation of polymer melt flow over thin-sectioned areas. Don’t forget also that gates in micro molding are often as small as 75 microns, which has a huge impact on shear heat.
Feature definition can also be significantly enhanced through vacuum venting which eliminates gas entrapment. As in common with many areas of micro manufacturing, however, vacuum venting is not always as simple as it may seem. While in terms of feature definition it typically produces positive effects, depth ratio can be affected significantly by material wettability and melt viscosity, and processing conditions such as injection velocity and mold temperature.
Experience quickly teaches you that when dealing with such tiny surface features, positive features are much easier to replicate than negative features. Also, retarding heat transfer significantly enhances feature replication. In some instances, especially when using semi-crystalline polymers, replication is optimised through the use of gas assisted micro injection molding.
For any micro feature in a tool, it is vital that the full depth of the feature is replicated precisely, and to achieve this requires a forensic understanding of material viscosity characteristics and solidification times. Replication is sensitive to flow direction, and can be improved by increasing cavity pressure and temperature within a certain range. Success is only achieved when the feature is replicated perfectly thousands and thousands of times. There is no room for half measures.
The critical nature of the process is exacerbated when it is considered where components and parts with such micro surface features are used. They are typically found in micro- and nanofluidic devices such as micro-pumps, valves, and flow sensors; micro-filters and micro-reactors; and nano-filters, channels, and membranes.
Very often, such products are used in the medical device sector, which in many ways is driving the requirement for smaller and smaller surface features, often in the area of microfluidics. Some of these components are in direct contact with blood and other body fluids, and there are also numerous optical and dental applications. In addition, the use of micro parts with micro surface features in an array of bioresorbable devices and permanently implanted devices is growing exponentially. So perfect and reliable replication from part to part is of paramount importance. It really can be a matter of life or death!
The tooling for parts with such small features can be made using a variety of technologies in various materials. For example, CNC machining, micro milling, and micro wire EDM are most often used to make steel tools. Electroforming techniques can be used to make nickel alloy tools, and UV, EUV, and E-beam lithography can make tools from silicon or glass.
Once again, the equipment used for such tooling processes is not commonly available to all, and requires that OEMs access it and harness its potential— and the necessary expertise to use it — via qualified and respected sub-contractors such as MES.
At MES, we offer a service that works closely with clients at every stage of the design to manufacture process. It is becoming increasingly the case that OEMs now see the value in “partnering” with sub-contract companies such as us in order to benefit from the 360 degree view we have of the process of developing such micro parts, components, and features.
For example, due to the enormous manufacturing challenges touched upon above, it is very rarely if ever the case that we are approached with a design that does not require reiteration to allow it to be manufactured at the size required or in one of a range of innovative materials that are often used in medical applications. It is only by tapping into a company such as MES, that such input is possible, and it obviously more cost-effective to engage us early in the design stage in order to avoid unnecessary reworking. The focus always comes back to one thing — design for manufacture.
So, what about our 84 million structures on a microscope slide? Well, obviously, the ability to able to manufacture with such micro surface details is central to a number of new innovations in a number of industry sectors. Key to the possibilities opened up, for example, is the way that such features add to the surface area of the part, and therefore increase it adhesive properties exponentially.
So, whether you are concerned with such cutting-edge micro molding developments, or something a little less ground-breaking, be sure to discuss your project with MES as early as possible. It is almost certainly the case that we will have ideas that you have not considered, and can assist you at the early design stage to ensure success in mass manufacture and replication.
Donna Bibber, President of MES would be delighted to discuss your requirements, and can be contacted on t. +1 (774) 230-3459 or e. donna@microengineeringsolutions.com
DOSE ONE: THE FUTURE FOR DPI’S, A HUGE OPPORTUNITY FOR COMMERCIAL PARTNERSHIP
9/10/13 An opportunity exists for a device / pharmaceutical manufacturer to partner with us to bring to market a revolutionary new singe-dose powder inhaler. DoseOne™ has been prototyped, tested, benchmarked, and is ready for pilot production and the support of a qualified partner to realize market potential. DoseOne™ is simple, inexpensive, and can be brought to market quickly as it is already designed, molded and ready for the incorporation of minor modifications depending upon particular drug/excipient molecule size.
The Market for DPIs. Powder inhalers deliver drugs in the form of dry powder directly to the lungs, and are typically used in the treatment of respiratory diseases such as Chronic Obstructive Pulmonary Disease (COPD), asthma, and emphysema. However, due to many of their innate characteristics and advantages as a drug delivery mechanism, there is burgeoning interest around the use of dry powder inhalers (DPIs) in the pharmaceutical and medical device sectors.
In many ways, DPIs have become more prevalent as they have been tailored for markets previously catered for by Metered Dose Inhalers (MDIs), which many patients find difficult to use, which rely on propellants that have come under more and more legislative scrutiny, and — from the device manufacturers and pharmaceutical company’s perspective — are often expensive to make. It is generally agreed that DPIs are easier to use as they simply rely on patient inspiration to deliver the drug, and are less likely to lead to side-effects such as irritation of the airways.
However, despite the inherent advantages DPIs have, there are also drawbacks, which can critically impact upon — among other things — vital issues such as patient compliance. For example, as DPIs require the patient to undertake an efficient and deep inhalation to administer the required dose, there is the opportunity for failure of the effectiveness of the device and therefore the efficaciousness of the inhaled drug. In terms of markets at which they are aimed, therefore, they are typically restricted to use in adults and older teenagers. In addition, as many DPIs are multi-dose devices, they need to overcome issues such as dose-to-dose inconsistency and the requirement for expensive dose-counting technology.
As with all families of drug delivery devices, the balance for drug companies is between affordability and functionality. Unit cost per device is obviously critical, as is the ability for the drug to be delivered in the correct dose, and for there to be minimum drug wastage.
The Solution is DoseOne™ . DoseOne™ is a single-use disposable DPI, and as such overcomes many of the problems associated with multi-use DPIs and MDIs. As a single dose device, for example, it minimizes dose-to-dose consistency risk, and also negates the requirement for priming needed by many devices, with all this implies in respect of drug wastage.
In addition, as DoseOne™ is a single use disposable device — and therefore a new device is used for each dose — it eliminates the frequent problem of powder caking and flaking which can affect dose volumes in multi-dose devices.
Also, as a single use device, the issue of, and problems associated with, dose counting — which preoccupies the FDA and other health organizations around the world — is made redundant. In its current state, DoseOne™ contains a simple dose readiness indicator as well as a dose delivery indicator in the form of a viewing window, therefore promoting patient compliance by confirming the dose is ready and has been completely administered. As such, DoseOne™ satisfies the regulatory demands previously only achieved by complicated and expensive designs.
DoseOne™ Design Characteristics. DoseOne™ is currently a three component inhaler, each component being simple to manufacture, with the long-term choice of material being determined by drug chemistry. The device design prohibits the use of very few available materials. Performance data at present is available using pharmaceutical grade/USP Class VI resins.
DoseOne™ has been designed in order to promote ease-of-use, there effectively being three steps, removal from packaging, actuation, and patient inspiration. Actuation is a simple compressive snap, the inherent simplicity of use making the device an ideal fit for the administration of vaccines in third-world and emerging countries, where simply, safe, and efficient self administration devices are so vital. It is vaccine ready and easy to carry and package for epidemics and pandemics.
The simplicity of the device makes it an inexpensive drug delivery option, costing $0.30 USD per unit in full volume.
DoseOne™ Design Status. US patent #7,832,399 has been granted to DoseOne™. Tools are constructed for the current DoseOne™ designs (Sizes #2 and #4), and Sizes #0 and #1 design embodiments are ready for tooling kick-off. Feasibility, optimization, and Design-for Manufacture details are all complete. Current single cavity tools are Phase I clinical ready, and devices are currently molded and fully functional.
DoseOne™ Partnering Opportunities. Micro Engineering Solutions (MES) has the exclusive worldwide rights to sell DoseOne™ and is now actively seeking serious and interested partners. The market is ready for a simple to use, cheap, and easy to manufacture single dose powder inhaler. There is a massive and immediate business opportunity, as well as the chance to be involved with the commercialization of a drug delivery device that can truly revolutionize and make accessible to all the treatment of numerous potentially fatal diseases.
For more details contact Donna Bibber on tel. +1 (774) 230-3459 or via email at donna@microengineeringsolutions.com directly.