Achieving Manufacturing Excellence in Wearable Biosensors

As wearable electronic devices become increasingly prevalent, manufacturers face the challenge of maintaining a competitive edge in the market. To succeed, it is crucial for companies to prioritize the effectiveness, cost-efficiency, and highest quality of each wearable device they produce. In this blog post, we will explore the key considerations and technologies involved in mass-producing wearable biosensors.

Mass Producing Wearable Biosensors

The key to cost-effective mass production of wearable biosensors lies in vertical integration and assembly operations. This entails the ability to print conductive inks on flexible substrates and perform converting operations, including lamination of medical-grade hydrocolloids, adhesives, non-woven and foam layers, hydrogel dispensing or placement, and final packaging. Successful techniques such as filling via holes with a .010" diameter have been employed to ensure continuity between skin contact and assumed communication devices, while also prioritizing patient comfort.

Technologies Used in Biosensor Manufacturing

The process of manufacturing biosensors involves various technologies, including screen printing, laser cutting, lamination, and adhesives. Screen printing allows for the application of different conductive inks such as silver, silver/silver-chloride, carbon, zinc, gold, and dielectric materials. Surface-Mount Technology (SMT) is utilized when components are required. The converting processes involve die-cutting, lamination of medical-grade foams and adhesives, and the dispensing and placement of medical-grade hydrogels. Printing through hole methods enable connections between the top and bottom printed circuits, accommodating up to six layers per side.

Supply Chain and Required Functions

Biosensor manufacturing typically involves a well-vetted, trusted supply chain since few possess all the necessary capabilities under one roof. The required functions can be outlined as follows:

1. Circuit/Electrode Printing:

   • Sheet or Roll-to-Roll (R2R) printing
   • Typically involves 2 to 5 print passes
   • Oven drying or UV curing after each print pass
   • Routine in-process measurements to ensure dimensional, ink thickness, and electrical specifications are met

2. Patterning of Spacer/Adhesive Layer:

   • Utilizes methods such as SRD, Rotary, Match Metal, and/or Laser

3. Patterning of Lid or Top Layer:

   • Similar methods as spacer/adhesive patterning

4. Dispensing and Drying/Conditioning of Functional Material:

   • Often performed by the OEM and contains valuable intellectual property (IP)
   • Increasingly adopted by medical converters to add value

5. Laminating:

   • Can be cold with pressure-sensitive adhesive (PSA) or heated (hot melt)
   • Performed by the OEM or converter
   • Option to skip lamination and instead die-cut individual sensor circuits for integration into injection molded plastic microfluidic cartridges or cassettes

6. Sheet/Roll-to-Cards:

   • Large-format materials are cut down to rectangular card formats, allowing compatibility with commercially available strip singulation equipment

7. Singulation:

   • Individual sensors are typically slit from cards into individual test strips

8. Packaging:

   • Singulated test strips are placed in plastic vials, often with desiccant-lined walls
   • Screw or snap caps are installed, followed by label application

Achieving manufacturing excellence in the production of wearable biosensors requires careful consideration of various processes and technologies. By prioritizing vertical integration, employing appropriate printing methods, optimizing converting operations, and ensuring quality throughout, manufacturers can meet the demand for effective, cost-efficient, and high-quality wearable devices in the market.