Layer built processes create a single part by building up  a series of 2D cross-sections. Different methods require different layer heights and have different means of supporting the layers that are hollow underneath. Of course, one advantage of this process is that parts can be made that could never be fabricated by traditional production methods, such as hollow spheres or even an assembly of multiple integrated parts in a single build that come out of the machine assembled (such as the links of a chain).

SLA (Stereolithography) – Liquid photopolymer (resin) is cured with a laser in layers. After each layer is laid down, the platform lowers further into the resin by the layer thickness, and the laser cures the next layer of material. The part is then post cured with UV light. SLA was one of the first additive rapid prototyping technologies and is still the gold standard.  It is good for general pupose form and fit protoypes and when parts require high resolution, smooth surface finish, or optical clarity.

A part manufactured by SLA (Photo Credit: Key Tech)

SLS (Selective Laser Sintering) – SLS builds layers similar to SLA, except instead of using UV light and a liquid photopolymer, a powdered material (real plastic or metal) is heated and fused together by a laser as a series of 2D cross-sections. SLS is a good choice for functional testing with real materials when smooth surface finish and fine resolution are not required.

A part manufactured through SLS (Photo Credit: Key Tech)

FDM (Fused Deposition Modeling) – Similar to a precision hot glue gun, long strands of real plastic material (ABS, PC, and others) are fed into the nozzle, melted, and deposited in a series of 2D cross-section layers. FDM layers are generally the thickest of the various processes, which limits feature size, but it usually provides better strength and robustness in comparison. FDM is good for prototyping functional parts without small features where surface finish is not important.

A part manufactured through FDM (Photo Credit: Key Tech)

Polyjet – Using inkjet printing technologies, UV-curable materials are effectively “printed” on top of the previous layer to create a 3-dimensional part. Polyjet can produce high resolution parts with decent surface finish, is generally cheaper and faster than most other processes, and is one of the only additive prototyping processes that can produce flexible parts.  It is a good process for small parts requiring good resolution and a decent surface finish, or when flexible parts need to be prototyped.

A part manufactured through Polyjet (Photo Credit: Key Tech)

Design engineering is a “tool” every medical device venture should take seriously.  Before searching for funding or lining up office space, your design must be thoroughly evaluated in its intended use.  Key Tech is the perfect partner for this, having spent the last 13+ years developing medical products.

Brian Lipford, VP of Strategic Development at Key Technologies kicked off the Tool Box Day by presenting an introduction to Key Tech.  His presentation is below:

After the presentations, we met with medical students, residents, researchers and some early-stage start ups.  Our advice to each of these entrepreneurs was the same:  Prior to engaging with Key Tech, you need to do your homework!

1. IP – Take a look at the patent landscape to see if your idea is unique.  At the very least, spend some time on Google poking around; it could save a lot of time and heartache.  It’s no surprise that without solid IP coverage, the deck is stacked against you.
2. Risks – What are the technical risks associated with your product?  What are the risks to the patient?  Medical device development is a risk-based business, so be comfortable with discussing this.
3. Funding - How will you obtain funding?  Key Tech may be interested in a joint venture arrangement with the right companies who are well funded.  If your idea has enough merit, Key Tech may be open to pursuing an SBIR grant.
4. Regulatory - What is your FDA regulatory strategy?  Does your technology fall into the streamlined 510k process, or is it going to be a more lengthy PMA application?  What are your potential reimbursement codes, because without them, you have no market!
5. Competition - Scope out your competitors.  Is it possible that they could be developing similar technology to yours?  Are you willing to compete with them?

Key Tech enjoys attending events like these because it gives us a chance to interact with researchers and professionals on the front lines of medicine.  Without their expertise, we are often times left doing needs assessments in a box, which isn’t very effective.  We love solving problems, but it takes partnerships with the right people to identify those problems.

Aris Melissaratos, Senior Advisor to the President of Johns Hopkins, spoke at the event about the $1.4 billion research budget at Hopkins.  He mentioned they are looking to improve their “return on investment” by spinning out more companies and ideas from the university stemming from their research.  We see this as a perfect opportunity for Johns Hopkins to reach out to the business community, and for the community to do the same to bring product innovation up to par with research at the university.

Are you a tinkerer? Even among engineers, I find that very few of us are willing to delve into the guts of a device with complexity outside our comfort range. I think kids have the advantage of not fearing whether they will be able to fix it later. They don’t think about how much it cost or whether it should be taken apart, and they’re confident an adult can provide a safety net. But, for those of us that are concerned about how best to crack open a $1,000 MacBook with a critical soda problem yet have the compelling desire to take it apart anyway, there is help.

Online video isn’t just for watching other people’s attempts at stardom. There are a host of instructional videos put together by generous people willing to share, learn from their mistakes, or just help you recover from what could be a $1,000 mistake. A quick search of YouTube or iFixIt can provide step-by-step examples of how to take apart a MacBook, replace a cell-phone screen, or repair a chainsaw carburetor.

As a tinkerer, perhaps you want to just build something yourself instead of buying it from a store. You can learn how to build a great HDTV Antenna from coat hangers or an automated Nerf Sentry Gun to protect the office.

Enjoy! (and let me know how you made out)

Disclaimer: Umm, it’s the internet, so you can’t always believe what you see, even in a video. Use your head.

The Scale

We chose an Acculab 210.4 scale because it was accurate enough (.0001 gram resolution, which is about a tenth of a microliter for room temperature water) and because it has a serial interface that we can call from Visual Basic to easily collect data and put into a spreadsheet. The data stream is limited to about 8Hz, but it was fast enough for our purposes.

Scales with more resolution often come with damping mechanisms to keep them stable. Although the glass cover keeps the air movement down, this one didn’t have a means to damp vibrations, so we needed to isolate the scale ourselves. We used a small table with some rubber feet as the foundation. Then we used one of those heavy engineering textbooks we have so many of on some thick foam and put the scale on top. Considerate use of flexible beams, soft materials, and masses meant the scale was rock-steady without any software averaging required.

The Fluid Connection

To get the fluid onto the scale, we attached tubing with a luer-lock fitting to a long needle inserted into the scale cover through a hole in the top plate and held in place with a thumb-screw. By using a needle instead of just inserting the tubing into the container, we eliminated any contact with the container or scale. we found that any such contact threw the scale out of whack, especially when the fluid flowed through the tubing with momentum.

The question came up as to whether the needle should be above the water-level or below it. If the needle is below the water-level, surface tension on the needle can reduce the weight of the water. However, if the needle is above the water-level, a drop can form at the tip instead of depositing the small volume onto the scale. We needed fine-resolution flow-rate data, so we opted to ignore the surface tension, which we found to be below the resolution of the scale.

Evaporation of the Water

Over the duration of a test, water will evaporate. The rate is dependent upon temperature, relative humidity, and the surface area of the container. Many suggest adding mineral oil to the water to create a barrier layer to supposedly eliminate evaporation of the water. Data showed that the oil layer did reduce the rate of evaporation (from 0.13 g/hr to 0.08 g/hr), although the oil ruined the plastic connections of the tubing by making them brittle and causing them to leak and break. Instead, we drilled a 1/4” hole into the cap of the container for the needle to fit through, which dropped the rate of evaporation by two orders of magnitude. We collected data for various configurations of the water, oil, and lid and plotted them below. So, without using any oil, we were able to drop the rate of evaporation from 0.127 g/hr to 0.002 g/hr.

Volume and Flow Rate

So, how does a measure of weight relate to volume and flow-rate? Well, the density of water is pretty well defined based on temperature (and weight / density = volume). Accounting for the error of this density value, as well as errors in the scale resolution and time resolution provided excellent measurement results by which to evaluate the devices.

It’s true that engineers have a particularly packed class-schedule, thus squeezing in classes outside their major seems superfluous. My undergraduate engineering program at UMCP required about 15 more credits than other curricula, so I, like other engineers, spent many evenings stressing over classes that I didn’t think were needed for my future in engineering.

It’s likely this student couldn’t relate macroeconomics to his own life (this was Summer 2008). However, since then, we’ve watched the failures of a few huge businesses send economic waves throughout the world. Companies, cities, states, and countries have gone bankrupt. Inflation and deflation are both serious worries. It’s a good time to understand a little about macroeconomics.

Engineers are notorious for falling somewhere between “a little nerdy” and “socially awkward”. A look around Key Tech does nothing to dispel that stereotype. But, it’s a fun crowd with interests in theoretical physics (admittedly, still nerdy), business, photography, nature, travel, cooking, brewing, farming, athletics, web development, and more. These interests developed when we were exposed to something  beyond the world of engineering.

Something that starts out as a chore might turn into a hobby or even shape a career path. It’s too early to discount the impact of a well rounded education on the rest of your life.

Key Tech outsources for prototype components and then assembles, details, and tests in-house. Prototyping capabilities are full service, including SLA, SLS, thermoforming, urethane, epoxy and silicone casting, polyjet, CNC machined parts, full electrical prototyping including microprocessor selection (in-house), board design (in-house), population and testing, user interface screen mock-ups with display software, and more.

Read more about the symbiosis of modeling and prototyping (PDF) for designing microscale parts in an article I wrote that was published in MICROmanufacturing Magazine this month, page 33 (Jan/Feb 2010, Volume 3, Issue 1).

• How can this be cleaned?
• Is it going to be dropped?
• What if someone sticks a finger in here?

As an engineer, it’s a good skill to have. But, is asking the right questions something that can be taught, or do you have to be born with this twisted skill?

If you’ve spent any time around young kids, you know that asking questions comes naturally. At that stage, “Why?” is one of the most common words in our vocabulary. We’re born with so many questions, and every answer simply creates more questions.

At some point, though, we have to refine this line of questioning, if only to get to sleep. Experience and intuition can help determine which answers are productive and which are just interesting. Draw the line. Give users some amount of responsibility, some amount of credit to their intelligence, and create some limit to the amount of abuse a product can take. Otherwise, the next handheld medical device will have a steel shell, cost ten times as much as it should, and take twice as long to get out the door.

Photo credit: arte_ram

Therefore, following extensive research and planning, we decided to utilize ISO standards, which are recognized worldwide, as the basis for defining our design processes. With a sturdy foundation, we were able to then tailor the system to our needs as a design firm, adding the necessary design strategies that would enable us to confidently provide our clients with the highest quality and most cost effective solution to their product development needs.

Since 2003, we’ve had a certified quality assurance program that not only satisfies the requirements of ISO 9001 and ISO 13485 but also enables us to efficiently design technically challenging products in accordance with many of today’s stringent design and regulatory requirements.  In other words, our quality assurance program, combined with our design and development procedures, enable us to quickly and cost effectively develop everything from simple mechanical parts to complex, automated, medical devices that require extensive regulatory compliance.  In addition, at the end of a project, we will have confidence that:

• we haven’t overlooked a critical design issue
• the product will be safe and effective for the intended use, and
• all the documentation necessary to verify and validate the effectiveness of the product design will be available to satisfy regulatory requirements or to transfer to our client for their documentation needs.

Most of the specific values of the product specification will come from external sources, as opposed to technical constraints. The spec will include the needs of the end-user, but any design is likely to also involve input from those people between the engineers and the end-users – a contract client, the marketing department, or internal management. In product development, there are very real market pressures to consider regarding sales, user needs, competitors, price, and more that will influence the overall design.

Specifications will vary from product to product, but there are certainly some aspects that are likely to show up everywhere.

Performance

Of course, most devices have to meet performance criteria as a major consideration of their success. This includes factors like accuracy, reliability, appropriate measurement or operating ranges, data logging capacity, or data transmission characteristics. These factors may be defined as minimum and maximum limits, to be determined later based on cost, technology, and other features. Try not to limit the possibilities yet, leaving room for compromises later.

Construction

Even if the materials haven’t been defined because of performance features still waiting to be designed, there are details that can be defined early on. We might define the parameters of a Drop Test, a maximum device weight, or other factors that will influence our choices of materials and assembly. Will the inside of the device need to be accessible for cleaning or service? How will the device be used?

Environmental

When products work fine in the lab and crash in real life, there may have been factors that were overlooked. Long-term problems like corrosion, moisture, dust, and UV damage can cause intermittent failures as the product is used and aged. Short-term problems such as operating and storage temperatures, poorly regulated power, or susceptibility to electromagnetic interference (EMI) can break a device under certain conditions while it seems to work fine at other times. Where will the device be used?

Appearance

Some engineers may not like to consider how a device will look before it is actually working. However, design and appearance are important factors in the usability, marketability, and overall attractiveness of a device. You may have a company color scheme or user interface requirements to meet.

Additional Factors

Depending on the product, there can be a variety of other considerations. For medical devices, safety and regulatory compliance are significant considerations to be determined early in the project. How the user will interact with the device is also important. Additional factors such as requirements for product reliability, serviceability, assembly, and documentation may also be defined. Here’s where we might include any operational procedures like setup or shut-down requirements, calibration, or testing.

Photo credit: Chris Baker