Molding Micro Surface Features
9/30/15 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 years.
Micro molding is 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.
The Right Powder Inhaler
9/23/15 Inhaled medication can be administered through inhaler devices. Inhaler devices are usually put into 3 categorizes: breath actuated inhalers (BAIs), pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). When inhalers are given to patients the following considerations must be taken into account: condition being treated, patients age, lifestyle, dexterity and preference.
PATIENTS: The biggest issue people are currently having with inhalers is patient misuse. If the patient doesn’t know how to use the inhaler properly the correct dose of medicine won’t reach the lungs to treat the patient effectively. When polled 75% of patients said they knew how to use their inhaler properly, but when they were assessed using their inhalers 90% of them were using it incorrectly. Pharmaceutical companies include a pamphlet with each inhaler showing the proper procedure for use.
The DoseOne™ inhaler has a very simple design and easy to use, cutting down on patient incorrect technique. It is a single use disposable dry powder inhaler that has only 3 steps to use it:
1. Removal from packaging
2. Actuating
3. Inspiration
There is no priming of the device and it contains a simple dose readiness indicator AND a dose delivery indicator.
PHARMACEUTICAL COMPANIES: 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. 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. Contact Donna Bibber directly to learn more at (774) 230-3459 or via email at donna@microengineeringsolutions.com.
Micro Magnifying Contact Lenses
9/16/15 Researchers from the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland have developed contact lenses that have micro-sized telescopic lenses built in to boost vision. They are controlled by smart glasses and react to the winking of the eye, which allows the wearer to zoom in on objects with a magnification up to 2.8 times that of an unaided human eye.
This prototype contact lens is just 1.55mm thick and has a two part magnifying region which is turned on and off when a person blinks. It is programmed to differentiate between a longer deliberate wink and a normal wink of the eye. The glasses that accompany the lenses let the wearer wink with the right eye to zoom in and wink with the left eye to zoom back out.
Unlike traditional contact lenses, these lenses are made from a more rigid, larger sclera lens from a number of precision machined plastic components, micro aluminum mirrors and thin polarizing films all held together with biologically safe adhesives. There are also miniscule air channels 0.1mm across the structure of the lens to allow for adequate oxygen flow.
These lenses were originally designed by the Pentagon’s research arm DARPA to enhance future soldiers vision capabilities in the field. In EPFL’s latest form the hope is they can become a visual aid for people who suffer from age-related macular degeneration (AMD). People over the age of 55 can develop AMD which leads to loss of sight in the center of the eye.
Microneedles in Drug Delivery Technology
09/09/15 Microneedles are used in transdermal delivery and is increasingly gaining traction as one of the more promising drug delivery technologies. Microneedles, on average about a few hundred microns in size, are capable of creating transient pores across the skin by penetrating the stratum corneum layer to deliver molecules. These needles are not big enough to reach the nerve-rich regions of the skin; as a result, the drug delivery is perceived as completely painless and devoid of bleeding. Drugs, proteins, vaccines, peptides and other biomolecules are suitable for delivery using the microneedle technology.
PR Newswire in London recently published a report on microneedles. They stated that the market is still in its infancy, with only 1 microneedle based delivery device having reached the market so far. But more than 25 companies, with proprietary microneedle technology, are actively working towards the development of microneedle-based drug or vaccine products, with them already in clinical trials. It is expected that about 10 of these products will be launched into the market by the end of this decade.
Why are microneedles growing in popularity? They can deliver a plethora of drugs and vaccines, in the form of a patch with solid or dissolvable micro needles which are virtually painless. Other research is being done to see what other markets this new technology can be used in. We here at MES have been involved in microneedle patch research and the future looks promising.
Medical Device Biologization
09/02/15 The process of combining technical and biologic components in a medical process or device is called biologization. It is a growing trend in the orthopedic field. In the past, orthopedic implants were mechanical and biological aspects were only considered in the process of attaching the device to the surrounding bone or soft tissue. More recently, biological coating was developed to help the implants to interact with and alter the surrounding biological environment to decrease adverse responses of the surrounding tissue, like implant infection and foreign body reaction. Currently researchers are exploring biological surface coatings and biologized implants that can be individualized by the patient’s own cells, lessening the negative after effects of implants.
Another example of biologization is molecular imaging that focuses on the development of imaging instruments, assays, imaging probes and quantification techniques to explain molecular mechanisms in biology and medicine. Molecular imaging is a non-invasive way to characterize and quantify normal and pathologic processes within the living organism at the cellular and subcellular level. In comparison to the traditional biomedical imaging using microscopy, molecular imaging is more advanced and offers more meaningful results and greater advantages. It can be conducted in vivo, can cross examine the entire body as well as focus on specific regions, and can visualize the specific molecular target in a 3D space. It is also becoming a key bridging technology to translate experimental preclinical findings into the clinical environment.
Last, but not least, biologization is used in tissue engineered and cell-based medical products and is used for the repair, restoration or regeneration of living tissue. The products include tissue, cells, organic and inorganic substances used alone or in combination with other factors that are manufactured, manipulated or altered in a lab. Tissue engineered and cell based medical products can also include substances that are not naturally found in tissues, for example bone graft substitutes and bone growth factors.