Streamlining Medical Wearable Device Design for Performance & Total Cost Optimization – Part 2

We sat down with one of our Field Application Engineers to discuss how to optimize and streamline Medical Wearable Device design. Boyd is an expert in streamlining innovative design, manufacturing, and assembly of medical wearables to help product designers and medical device companies design for excellence (DFx). We help designers consider patient comfort & safety, manufacturing efficiency, product lifecycle, and total cost while navigating complex regulatory processes, providing global agility, assuring business continuity, and accelerating time to market.

Here are common questions we get as we work through Medical Wearable Device design projects with leading medical device design and manufacturing clients:

How do you incorporate electronics and functionality into extremely thin medical wearable devices?

Medical Wearable Device designers are tasked with packing a lot of sensitive and critically important electronics into very thin, streamlined wearables. There are all different types of sensor technology used because as sensors get smaller and less expensive, they’re being integrated into more devices and enabling new medical technology.

Types of Sensors Used in Wearable Devices

Electrocardiogram (ECG) monitoring devices, as an example, sense electrical stimulations based on the location of conductive electrodes worn on the chest. These patches are used to sense things like heart rate, respiratory rate, and arrhythmias. Product designers are also learning how to adapt acoustic sensors to collect heart metrics in different locations like the wrist.

Medical Wearable Devices also sense skin or body temperature with thermistors or thermocouples. Optical sensors on a wearable can measure oxygen saturation. Accelerometers and Gyroscopes can measure the wearer’s activity, movement, and positioning and can measure things like posture and fall detection.

Sharing Medical Wearable Device Data

Each sensor collects data that connects to either an embedded circuit board sandwiched within the wearable patch, or through electrical snap connectors to an external, reusable electronic module affixed to the wearable. Most of these wearable devices are using a Wi-Fi or Bluetooth transmitter to broadcast data to a secure cloud storage source accessed remotely by patients and doctors. Sensors and electronics must also be powered by a small battery which must be considered in the assembly process.

Assembling Medical Wearable Device Components Together

Medical Wearable Devices feature a large amount of very small, precise components. Due to their slim designs, there isn’t much room to accommodate all these components and there is certainly no room for misalignment. Meaning design for manufacturing and assembly accuracy are exceptionally important. Boyd has a lot of complex rotary converting processes that we leverage to cut and assemble with tight tolerance control and registration accuracy in highly automated processes. However, many medical wearable designs cannot be fully converted “on-press” in one continuous process utilizing the efficiency of traditional reel-to-reel converting methods. Because of complexity of the components used like the insertion of an electrical assembly or the attachment of snap connectors or the addition of a molded plastic housing, separate assembly steps are often required. This presents special assembly challenges that require creative process flow and innovative assembly fixture design to achieve efficient throughput and reduced labor costs.

Balancing Volume and Assembly Cost for Medical Wearable Devices

Newer medical wearable designers face special challenges as start-up companies who are trying to introduce a new technology into the market, facing long product development cycles due to regulatory / compliance requirements, and a slow ramp up due to long time of adoption. This means the economics for a fully automated assembly process are typically not feasible given the high NRE investment. Often it comes down to an efficient manual or semi-automated assembly process to help minimize these non-recurring expenses to give your wearable the best chance to succeed in the market. This is where Boyd excels in determining how best to assemble a complicated design in an efficient manner, leveraging the best of our diverse processes to assure trusted quality control. Blending the best of high precision converting with innovative assembly techniques under a highly documented, and process-controlled quality system.

Streamlining Medical Wearable Device Design for Performance & Total Cost Optimization – Part 1

We sat down with one of our Field Application Engineers to discuss how to optimize and streamline Medical Wearable Device design. Boyd is an expert in streamlining innovative design, manufacturing, and assembly of medical wearables to help product designers and medical device companies design for excellence (DFx). We help designers consider patient comfort & safety, manufacturing efficiency, product lifecycle, and total cost while navigating complex regulatory processes, providing global agility, assuring business continuity, and accelerating time to market.

Here are common questions we get as we work through Medical Wearable Device design projects with leading medical device design and manufacturing clients:

What are the best and safest ways to attach Medical Wearable Devices to the skin?

There are two important factors to consider regarding the attachment of the medical wearable: The attachment of the device itself to the skin and the style of conductive electrode used. All devices that attach to the skin must be highly tested and regulated to assure patient comfort and safety. Wearable devices must reliably attach to the patient for intended wear times without irritation while still being removable without damaging patient skin.

Wearable Device Adhesive Considerations

Selecting the right medical grade adhesive for wearable devices are selected based on:

• Required adhesion level (for example higher adhesion is necessary for longer wear times),
• Breathability: water against the skin needs to escape to help promote better wear time
• Ease of Removability,
• Wearer Comfort Level,
• Repositionability or Re-application (if required), and
• other application considerations.

Medical Wearable Design and Use Conditions

The shape and type of the skin contact layer may also be influenced by whether the wearable device needs to protect hydrogel electrodes or sensitive electrical components sandwiched within the patch from outside water ingress. In some unique applications when wear time is short, water ingress is not a factor, and repositionability of the wearable is desired, the adhesive skin contact layer can be foregone and rely on hydrogel components to provide the desired level of adhesion. We collaborate with many global raw material suppliers that are the world’s leading innovators in skin contact comfort and performance to help recommend materials to customers based on these factors to improve product comfort, care, and safety.

Medical Wearable Device Electrode Components

As for the electrode component, one traditional type of material used is open cell, medical grade foam pad saturated with a conductive gel as the electrically conducting medium. This style electrode can be more difficult to handle as a raw material and can impact manufacturing efficiency and cost. We have been steering customers towards hydrogel-based electrodes. Hydrogels present some cutting challenges, but our proprietary converting methods can offer a better option: they’re available in roll form and solid means a component easier to cut, handle, and place with greater quality control. There are several different global hydrogel raw material manufacturers available that offer responsive support and supply chain stability, enabling us to secure dual sources that can be compliant with regulatory and certification controls. Many material formulations to choose from, means we can typically find the right hydrogel to fit the specific electrical and application requirements.

We’ll continue our interview with our Medical Wearable Device FAE in an upcoming post!

For technical printing projects, Boyd provides support from development all the way to production.

This blog is the second in our series on technical printing. In our first blog, we gave an in-depth description of what technical printing is. In this blog, we will talk about how technical printing projects go from development to production.

How are technical printing projects started? At Boyd, technical printing projects start in our development department where the design is inspected, reviewed, and tested. The goal is to produce development part designs and quickly determine if the part is manufacturable. Our printing team will provide design considerations and test reports until a conclusion is drawn. Once a batch of parts has a high yield per volume and a high success rate, the project can move onto full production.

Phases of Technical Printing Projects

There are five phases that technical printing projects go through during development before they can move on to full-scale production, each with specific operations. These phases are particular to technical printing projects only because of the high level of scrutiny required in development.

Phase 1: Ideation

Ideation is an ongoing conversation between the customer and Boyd to identify the areas of the highest design risk. This allows both parties to define steps to test design assumptions and evaluate potential design and material solutions to help build confidence about the known challenges.

Phase 2: Risk Mitigation

The Risk Mitigation phase is used to validate material stability and printability, explore material handling and registration options, review curing processes, and establish a planned production approach. Defining the risks and challenges that are likely to occur allows for a plan to be made accordingly. All challenges must be addressed with care as technical printed parts require much tighter tolerances.

Phase 3: Low-Volume Functional Prototyping

Low-volume prototyping is used to create functional printed parts using the materials and preliminary product design planned for use during full volume production. This may take several rounds of prototype layouts and testing until a high yield success rate is achieved. With technical printing, projects in this phase become more device-specific and are outside of typical production, development, and industry standards.

Phase 4: Production Development Prototyping

With a suitable design identified, Boyd will work on transitioning into production manufacturing development. Larger quantities of parts will be printed and evaluated, with the goal of meeting customer specifications. Technical printing requires more rigid quality standards and process control, which is why Boyd implements such rigorous production reviews.

Phase 5: Production Validation

Once the parts have passed production development prototyping, the project is handed to a production team and design engineer to apply to production volume quantities.

Boyd’s expertise and strict quality systems allow us to work in these highly regulated spaces and gives our clients confidence in the parts we produce for them. In our next blog, we’ll be going over the qualification procedures for a technical printing project.

Ready to start your technical printing project? Contact Boyd to get started!

For functional printing that requires tight tolerances and specifications, technical printing techniques are the perfect solution.

This blog is the first in our new series on technical printing. Throughout this series, we will describe the procedures involved in creating technical printing solutions, from start to finish. To begin, we’ll focus on defining technical printing and what it’s used for.

Introduction to Technical Printing

Technical printing is a generic term used for functional printing projects that fall outside industry standards, materials, processes, and specifications. These projects require extremely tight tolerances and critical product specifications, typically belonging to highly regulated industries, such as the medical industry. The processes follow current Good Manufacturing Practices (cGMP), which are regulations enforced by the FDA to ensure products consistently meet the required quality standards. Technical printing and functional printing are both used for similar applications, such as for membrane switches. Functional printing has more forgiving specifications while technical printing has much tighter requirements.

Examples of Technical Printing Projects

A common example of technically printed parts is printed electrodes, which are strips manufactured for electrochemical analysis. This involves technical printing because they are typically used in the highly regulated medical field, in applications such as diabetic test strips. When manufacturing printed electrodes, conductive lines are intricately printed on polyester, typically using conductive inks including carbons, silvers, and silver-silver chlorides.

With technical printing, applying a conductive ink to a surface is similar to the process of applying frosting to a cake. When you squeeze a bag of frosting, a controlled amount comes out of an opening at the end. This same process is how conductive inks are applied as circuit lines on polyester substrates during technical printing.

Technical Printing for the Medical Industry

Boyd frequently manufactures electrodes for electrochemical test strips and devices, such as diabetic test strips or quick diagnostic labs. Boyd prints electrodes with silver, carbon, or various conductive inks to measure a current or other signal. Our customers will then apply a reagent on top of the electrodes. When those reagents are exposed to bodily fluids such as blood, a chemical reaction takes place and the electrodes will detect that reaction and send the signal to the device it is powered to. This is done on a tiny scale and the readings of signals must be completely accurate, which is why this part requires technical printing with a high degree of scrutiny. Large variances in the circuit alter results and can cause the test strips to fail, so tighter tolerances of technical printing are necessary.

Many variables go into technical printing projects, such as the curing times and quality of inks, as well as the substrates and thicknesses used. These variables are closely controlled, especially when making electrodes for medical equipment. These parts go on critical equipment and could mean life or death in certain situations, such as buttons for a medicine administration device used in hospitals or printed electrodes used in diagnostic labs for diseases. Boyd is a trusted manufacturer for technical printing projects with years of experience in the medical industry and other highly regulated industries.

In our next blog in this series, we’ll be going over how technical printing projects go from development to production.

Smart wearables are becoming ubiquitous and witnessing revolutionary developments each day, fueling a multi-billion-dollar industry. From medical wearable devices to collect diagnostic data, smart tattoos that track sunlight exposure, to smart insoles that monitor your footsteps, technological advancements are pushing the boundaries of wearable innovation. As the wearable industry is still relatively young, functional printing professionals including technical printers, designers, engineers, and system integrators are constantly working together to investigate new processes, materials, technologies, and testing methods. Aside from the dominant world of smart watches, there has been significant growth and interest in smart medical wearables, clothing, electronics, and sensor solutions. But what are some of the common considerations when developing a new smart wearable?

Biocompatibility:

Since most wearables come in direct or close contact with skin, biocompatibility is of paramount importance to ensure user safety. Depending on the intended use of the device, compounds in wearable substrates and construction layers can potentially be exposed to sweat, rain, humidity, sunscreens, and insect repellants. A comprehensive understanding of the interaction of various external factors is crucial towards eliminating unwanted risks such as skin sensitization, allergic reactions, and irritation. While there are no industry standards governing biocompatibility across all wearable devices, ISO 10993 provides a framework for wearable medical devices.

Power Management:

Effective power management still remains a significant hurdle in developing wearable solutions. Thin and compact batteries often translate to shorter battery life and companies are continuously struggling to extend the battery life for devices to last at least one cycle of usage. While space is a huge constraint when working with small and lightweight devices, companies are harvesting energy by employing solar cells or powering batteries using the body movement and body heat of the wearer. Companies are actively trading Wi-Fi connectivity with Bluetooth communication modules for efficient power consumption and pivoting towards wireless power supplies through inductors. For most wearable garments intended for long-term use, the batteries must be easily replaceable or rechargeable.

Flexibility and Stretchability:

Smart wearables, especially garments, are susceptible to a great deal of stretching. Flexibility, the basic form factor of wearables, has made flexible printed electronics be actively pursued as an alternative to costly silver threads and yarns sewn into apparels. Depending on the final application, wearable substrates need to strike the right balance between flexibility, stretchability, and stability. In addition to experimenting with new substrates, the industry is currently leveraging medical-grade materials including polyether-based thermoplastic polyurethane (TPU), polyester-based TPU, polyethylene terephthalate (PET), and fabrics such as spandex, nylon, elastane, and cotton. Functional inks are often printed on flexible substrates and as the user wears or moves with the garment, there is a certain amount of stretch that occurs. Therefore, inks need to exhibit acceptable change in resistance with repeatable stretch and recovery cycles.

Sealing:

Conductive epoxies, typically used to apply components on to circuits, are often not a feasible solution when dealing with wearable applications as they tend to break under stress. Due to this, applying additional components such as surface-mount LEDs and active PCBs can be challenging. The ability to incorporate electronic components smoothly into apparel whilst ensuring strong adhesion during bending, creasing, and flexing is key to the success of smart wearables. In addition, smart and medical wearables intended for long-term use must be safe to submerge under water without damaging the circuitry, and physically endure multiple wash cycles. Achieving a water-tight seal and protecting the power source from environmental factors is vital for ensuring optimal performance and durability of the device. For electronic equipment, Ingress Protection (IP) rating specifies the degree of protection from solids and liquids including dust and water. Whether it is fusing stretchable materials with thermoplastic-adhesives backing or applying hot-melt adhesives to polyester circuits, thermal bonding is one of the most common sealing approaches in wearable solutions. Pressure sensitive adhesive (PSA) lamination is another approach that requires a medical-grade adhesive to apply a patch directly to the skin of the user. TPU overlaminates, printable insulators, and PET overlaminates are often used for sealing and potting. The wearable technology industry is migrating towards a “smart system”, a world where all devices from head to toe communicate with each other to create a single ecosystem. As existing technologies and processes evolve, new norms, standards, and specifications for the industry will gradually develop. With a promising future in sight, the widespread adoption and integration of smart wearables in our daily lives will continue to grow. Boyd has years of experience creating custom smart wearable solutions. To learn more or discuss your project needs, schedule a consultation