Boston Device Blog

Lantos brings a game-changer to Audiology

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Have you heard? Getting fitted for a hearing aid will never be the same again.

Cambridge, MA based Lantos Technologies has engaged Boston Device for product design and development of a handheld digital scanner to bring the process of creating hearing aids into the 21st century. Now, rather than having a tube of silicone squeezed into your ear, Audiologists will be able to quickly scan the inner and outer geometry of a patient's ear with a simple handheld device. This results in a detailed 3D representation of the ear for better communication with hearing aid manufacturers, a better fit for patients, and a lot less mess for Audiologists.

If you happen to be attending the American Academy of Audiology's AudiologyNOW! Conference (March 28-31 @ the Boston Convention and Exhibition Center) be sure to keep an eye out for the Lantos booth where they will be unveiling the latest version of the device and doing live demos. 

Prototyping Using Sourced Parts | MIT Workshop

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Recently, we ran a workshop at MIT for mechanical engineering undergraduate students in the class, 2.009 Product Engineering Process.  This is a capstone engineering course where teams of 15-20 students design and prototype a functional product within the timeframe of a single semester.  Since this is a significant challenge in a rapid time-frame, one of the important learnings is to leverage sourced (or off-the-shelf) parts when building early prototypes.

For this workshop we tasked the students to build a functional coffee maker using only sourced parts.  These parts could come from Mcmaster, Amazon, Grainger or any other online supplier of hardware that ships in less than 2-days.  The students had one 3-hr session to design and source parts, and a second 3-hr session to build the functional coffee makers.  A tall challenge to say the least!   

Following are some pictures from the workshop.

The students started off by brainstorming their coffee makers on paper.  As if building a functional coffee maker isn't enough, we asked the students to personalize their makers or make them fun in some way.  Most of the teams finished the brainstorming task in about 20 minutes.  

After the brainstorming, the students hopped on laptops and searched for parts that matched their ideas.  The classic McMaster catalogs also came in handy for this sourcing exercise.  All of the teams build BOMS (Bill-of-Materials) with suppliers, part numbers and descriptions of the parts to be used in their prototypes.  The BOMs were collected, and used for ordering all of the supplies.

Next session, the boxes arrived, and the teams immediately jumped into buildling.  Holes were drilled and lengths of parts were cut, but no other fabrication was allowed.  The teams encountered unexpected sizes of pipe diameters, sealing challenges, and heat dissipation challenges to name a few.

Breadboarding Versus Prototyping

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While the terms “breadboarding” and “prototyping” are often used interchangeably, they are unique stages in our device development process. Here, we’ll explain breadboarding, and outline how it differs from creating a prototype. Both are integral to quality design and serve separate, but essential, purposes.

The term breadboarding originates from the early days of amateur radio. Experimental radios were developed by attaching copper wires or terminal strips to a wooden board—often a bread cutting board—and soldering electronic components to them. The board provided a surface to attach schematic diagrams and mounting posts, which were often thumbtacks or small nails.

Breadboarding has evolved over time and is now used for a wide range of devices. At Boston Device Development, we use "breadboards" to evaluate and optimize subsystems. Our breadboards are often mounted on aluminum plates, and allow for the swapping of actuators, springs, or other key components. The purpose here is to test basic function by having the ability to tinker with the design as needed. Breadboarding is meant to test and re-test a device in order to achieve the desired functionality quickly. Breadboards serve as a “rough draft” that aim toward functionality but does not look like the eventual final product.

In contrast, a prototype is much more refined, aiming to represent a system-level design. Our prototypes typically integrate aesthetics and production-grade materials to create a working model that is a more accurate rendition of the finished device. While some testing may occur using prototypes, at this stage the design will be much closer to completion and the focus is on fine-tuning for manufacturability, ergonomics and aesthetics.

Boston Device Development’s extensive knowledge of materials, fabrication, and assembly methods enables the engineering of functional breadboards and prototypes that can then be perfected through iteration. Our advanced processes include CNC machining, rapid injection molding, and additive printing (SLA, SLS, FDM). Additionally, the engineering team is well-versed in assembly methods with capabilities in UV adhesive bonding, wiring, soldering, and precision mechanical assembly.

Inspections are performed on all components and valuable information is gathered through rigorous protocols and evaluations. The results of this verification are recorded in the product’s design history file, and are a resource for future design developments.

Photo by Jim at sonicchicken.

Understanding the Practicalities of Research vs Development

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Although many companies combine research and development into one line item in their financial reports, these two concepts have very different meanings from a practical perspective. It is important for companies to understand the practicalities of research vs development in order to help improve the bottom line, and to maintain reasonable expectations of their development programs.

Research vs Development

During the research phase, it is normal to expect shifting timelines, unpredictable results, and exploration of new paths. The purposes of the research effort are to make discoveries, perform experiments, and provide thorough documentation and analysis - processes which can take a long time.

Development, on the other hand, is typically driven by strict deadlines and limited budget constraints. If your project is funded based on completion of key milestones, timely completion of tasks becomes even more important. The project management approach required for research vs development is clearly very different. 

Optimizing Resources

There are many companies that are proficient in either research or development, but not both. When a project shifts from the research phase to the development phase, the human resources required are often different and the cost priorities change. Not every business is properly equipped, financially or practically, to successfully make this shift.

If your company has strong research skills but lacks in the development area, consider partnering with a dedicated development firm that already has the staff, equipment, and resources to execute your development plan within the required time frame. You will save a substantial amount of time and money for the following reasons:

• You do not need to hire new staff
• No need to purchase new equipment
• Experienced managers will keep your project on track
• Regulatory quality requirements will be met
• The latest technologies will be available
• Integrated best practices enable rapid development and lower budgets

If your company has an imbalance with respect to research vs development, consider partnering with a qualified firm that has a proven track record. You can save time and money without sacrificing quality results.

Photo by United States Government Work.

Medical Device Prototypes Need to Adhere to High Standards

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When considering medical devices for clinical use, to think of a product as a “prototype” can be misleading and detrimental to the development cycle.  Unlike prototypes created for commercial use outside of the healthcare field, clinical trials for medical device prototypes must produce results identical to those intended for the final release product.  Essentially, there is no “back to the drawing board”—medical prototypes must produce statistically consistent results over differing clinical environments.

Consequently, is better to think of the first clinical trial as not really a trial at all, but instead, as the first commercial use of the device.  

Clinical trails are a key milestone in the approval process of a device and often future funding of the project depends on the results of such trials.  It is therefore important that the prototype pass regulatory safety standards as quickly as possible.  The change-control process must be rigorous and record keeping meticulous.  Any delays in approval of clinical trials can cost companies dearly in terms of funding, marketing, and competitive edge.  The idea is to get the product to market as quickly and efficiently as possible.  When going before an institutional review board (IRB), companies must be ready to prove that the device has already arrived at safety benchmarks that comply with the IRB committee’s requirements as to the welfare of the intended participants of device trials.  If the IRB is unconvinced--due to prototypes that are imperfect or need future revision--valuable time and money is lost.

It is also crucial to ensure that users can realistically expect the same results throughout the full lifecycle of the device.  Unlike other, non-medical, prototypes that can be brought to the trial phase looking or acting nearly the same as what you expect the final release to look and act like, medical prototypes must, for all practical purposes, be undifferentiated from the final product. The prototype will not perform or function any differently from the product that is brought to market. For these reasons, it is better to think of medical device prototypes for clinical use instead as a preliminary manufactured product.  

Complex Device Design Using Subsystem Iteration

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Divide and conquer. That’s the way to design complex systems of any kind - mechanical, electrical, software, or any combination thereof. Don’t try to design a large or complex system as a unified whole but instead, segment it into a number of self-contained subsystems. 

Cramming all features and functionalities into an integrated system causes an inordinate increase in the amount of money and effort required for design, engineering, prototyping, and testing.  One modification has a domino effect on all other related features in the system.  An integrated system approach from the get-go can cause schedules to drag and budgets to bloat.

Partitioning a planned system into a set of core subsystems tends to improve overall designs right from the start.  Primarily, this approach saves time.  It enables achieving core functionality early in the development process.   After the functionality is attained, the integration of subsystems into a cohesive system design becomes a matter of implementation.

Once the core subsystems are defined, each may be worked on by a separate engineer or team. Regular communications will be necessary, but by and large, each subsystem can be engineered and evolved as its own, self-contained component - a method generally known as subsystem iteration.

This works, of course, only if the mechanical, electrical, and/or logical interfaces that link these subsystems are precisely defined. Great attention must be paid to these interfaces but the payback will be substantial. Designed properly, interfaces act as firewalls, segmenting disparate sets of function from each other in a way that greatly benefits the design, testing, and trouble-shooting of the finished product. 

While subsystems do need to be integrated longer-term into a cohesive system design, taking the divide and conquer approach to achieve core functionality is a more robust and efficient process. 

Solidworks Tips - Top Down Modeling

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Solidworks is an invaluable tool for the modern engineer and allows them to bring ideas to market quicker, prototype faster.  However, modeling a part, a sub-system, or a top-level assembly is often times easier said than done.  Often times, it takes not only an intricate understanding of what is to be designed and the engineering challenges, but also a good deal of planning ahead so that your model is "robust" and easily adaptable to downstream changes that inevitably occur as breadboarding, prototyping, and other outside variables drive design changes. 

One way of achieving a "robust" Solidworks design is through the practice of top down design.  What is top down design?  In the most simplistic sense, it is creating a hierarchy wherein the framework for an entire assembly is designed before that of the individual parts.  This framework, referred to as a "master model", behaves as the groundwork for which all the individual parts and components are created.   Because these parts are all parametrically linked together through the master model, it is possible to make numerous changes to parts within an assembly by merely revising the master model without fear of interferences or other design head-aches.  Here are some general tips to top down modeling;

Sketch your concept.  The easiest way to get out of the habit of bottom up modeling is to create a rough sketch of the system or the assembly that you are about to design.  This sketch is primarily used for identifying key engineering challenges and the necessary components that need to be designed or integrated into a system.

Build a "Master Model".  Now that a rough sketch has been created and all pertinent parts to a system have been identified it is time to create a master model in Solidworks.  Start by opening a new part file and from the rough sketch start laying down 2D sketches that will drive the base features to all the parts in an assembly.  Be sensitive to how your base features will be created (extrusion vs. revolve) and build the sketches accordingly.  Create new datum planes and features where necessary and fully define your sketches with dimensions and relations.  When complete save the part file and assign it some sort of nomenclature so that your recognize it as the master file.  An "_master" suffix works quite well.

Create the individual part files.  This is the time to break out the individual parts and finish up the design details.  Open up a new part file and go to Insert-> Part.  The Solidworks' File Open Window will now appear and from there you should select the the master model file which you previously designed.  In the Solidworks Feature Manager select the design features from the master model which you would like to carry over into the part file.  By clicking the green OK check mark, the master model is automatically located to the same reference planes which they were initially created.  After inserting the master model expand the design tree to view the various sketches and select the base sketch for the part which you would like to design.  Utilize the appropriate feature operation (i.e. Extrude, Revolve) to create the base feature for this new part.  After this is completed you can finish whatever detailing may need to be done to the part.  This same methodology can be applied to the remainder of the parts that need to be created.

Build the Assembly File.  The final step is integrating all your parts and up-front work into a final assembly file.  This is where you should recognize the benefits of the top down modeling scheme.  Start off by creating a new assembly file.  Before going ahead and inserting the part files in the assembly you are going to want to first want to insert an "Envelope" of your master model.  Go to Insert->Envelope->From File...  and select the master model file.  It may appear that nothing has happened, but take notice that in the modeling frame the cursor has a part icon beside it.  Click anywhere in the frame and an envelope of the master model will be dropped into model.  Similarly to a part file you will want to mate the Front, Right, and Top planes to that of the assembly file.  Now go ahead and start inserting the indivual parts into the assembly file and voila! there's your assembly.  Need to make changes to the assembly that impact the base features?  Simply expand the Envelope in the design tree and edit the base sketch as necessary and rebuild. 

Here is a short video of a simple calibration assembly being created using the top down modeling method.

Prototyping Tips - Building Robust and Functional Prototypes

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Building functional prototypes is more than simply printing parts and gluing them together.  It requires a deep understanding of the prototype materials and fabrication methods that are used to construct parts.  In certain cases, part fabrication methods may result in insufficient resolution or materials that are too brittle to withstand certain types of usage.  The various prototyping methods are beyond the scope of this article, but following are some general prototyping tips for creating robust visual and functional models:

1. Use pins to align parts where fasteners are not possible.  In many production devices, parts are snapped or ultrasonically welded together in order to avoid using fasteners.  However, employing these methods in prototypes is typically not practical.  Reason being is that prototypes often need to be opened and tweaked multiple times in order to adjust fit and swap components.  So, the best method of holding parts together while allowing for repeat adjustment is the usage of fasteners.  However, fasteners don't always fit in tight places where a snap, weld joint or adhesive might be in a production design.  In these places we typically use press-fit alignment pins to keep the parts together.  Press-fit dowel pins typically come in increments of 1/32" and are available in hardware supply catalogues such as McMaster-Carr.
2. Build in reveals to disguise parting line mismatch.  When parts are fabricated, they slightly distort due to heating, external forces, painting and a variety of other factors.  If parts without reveals are fastened together, this distortion is quite evident.  Reveals disguise distortion that occurs along parting lines.  A person's eye is unable to detect mismatch between parting lines when a small gap exists between adjoining parts.  We typically design mating components with a lap joint that forces a bottom-out location and defines a reveal between the external parting lines. 
3. Use soft-touch paint to simulate rubberized texture areas.  Many production devices use TPE overmolding to achieve the rubberized texture in human touch points, such as handles, grips, button faces, etc.  This overmolding process can be replicated through urethane casting processes, but this often significantly increases the cost and time of prototype fabrication.  A quick way to simulate overmold areas is to simply finish the parts using a soft-touch paint.  This paint creates a matte finish with a rubber-like texture.  Soft-touch paint does not provide the compliance that an overmolded or low-durometer urethane cast part will, but it achieves the basic look and feel in a fraction of the time and cost. 
4. Build and finish separate parts instead of masking.  Very talented and careful modelmakers can mask parts to simulate color and texture breaks or parting lines.  However, we find that a much more reliable route to creating clean parting lines is to separate parts, paint / finish them separately and attach them together when complete.  Perfectly masking parts (especially those with compound surfaces) is extremely difficult, and overspray is often noticeable when finishing parts in this manner.  While it takes a bit more time on the engineering side to split out separate parts and provide sufficient clearnance, it results in a much higher quality finish.
5. Design parts with sufficient clearance.  Most additive rapid prototyping processes (i.e. SLA, SLS, FDM) run slightly on the large side.  So, when designing mating parts it is critical to integrate sufficient clearance.  You will be kicking yourself if you rely on sandpaper or files to help you out after the parts are fabricated.  For parts that would fit inside of an 8" cube, .010" of clearance is generally sufficient.  

In summary, good prototypes are a result of good engineering.  It requires a bit of additional time and effort to make sure that parts are designed for their respective prototyping methods and materials, but this time is typically much less than the time required to modify parts after they have been fabricated.