Case Study

Consumable A/pH
Sensors for Dialysis

From Multiple, Manual Processes to a Faster, Automated Manufacturing Line While Maintaining Critical Tolerances and Mitigating Safety Risks

Ascential designed and developed a complete manufacturing line for A/pH sensors that exceeded quality requirements while creating an automated manufacturing process that drastically reduced production costs and exceeded throughput expectations by 40%.

Overview

As part of their mission to deliver transformative kidney health technologies, a subsidiary of a major Dublin-based medical device manufacturer developed a new home dialysis device that would improve accessibility to care, ease of use, and clinical performance. But to realize these improvements, the client needed new consumable A/pH sensors that could read the saturation level of ammonia in the water being recirculated in the dialysis machine. The sensors had to be highly accurate, as they monitor the water and indicate when the filters must be changed for the patient’s safety.

The client also wanted to improve throughput in the production of these sensors. By engaging Ascential early in the process, our expert team was able to design for manufacturability, not only achieving product specifications but also reducing equipment costs and exceeding throughput expectations.

Challenge

The sensor prototype originally developed by the client utilized a punch dot card, and the dots on the card could only be handled manually with tweezers. The client had set up a rudimentary pilot line to model the development of the card and establish process limits, but they needed Ascential’s expertise and resources to achieve the desired accuracy and performance requirements. They also knew that the current design could not be automated for high volume production.

The client wanted to achieve 30 sensor strips per minute in throughput, but their original pilot system had fallen far short of that goal. Ascential was selected to develop an upstream and downstream process that could deliver on this goal while ensuring product quality and accuracy.

Solution

The Ascential team assessed the project requirements, then set out to 1) improve the A/pH sensor design, optimizing it for quality, accuracy, and manufacturability, 2) develop a production process which leverages automation to enhance throughput and reduce costs, and 3) ensure the new system has monitoring and inspection capabilities to reduce risk and downtime.

Sensor Design

The client chose Ascential because of our deep experience using lateral flow assays for testing applications such as blood glucose strips. After analyzing the prototype and scope of work, our experts designed a new ApH sensor card consisting of six indicator films pinched between two layers of substrate.  By redesigning the chemistry positional pattern, our team could accommodate a high-speed lamination process for placement.

The team delivered a product designed for production efficiency and scalability. The resulting card delivered a single array containing 20 test strips.

Process Development

To reduce time-to-market, the Ascential team was simultaneously working on a fully automated prototype line to produce the sensors during product design and development. Ascential built an upstream and downstream process that would develop the raw film material into the finished sensor film, then move it into slitting, assembling, and packaging.

The dying and etching station was redesigned to drastically reduce the duration of time required to produce a card and increase throughput. The new system had several capacity improvements, including:

  • Web length increased from 25-50 meters to 50-300 meters
  • Solution tank capacity went from 1 liter with no top-off to 5.5 liters, plus an additional 5.5 liters for automated top-off
  • Ammonia wash station size increased from 25-50 meters to 50-300 meters long, and wash tank capacity increased from 5.5 liters to 125 liters

The Ascential team also simplified the build of material for the new systems by selecting components which they had previously designed, tested, and proven. This resulted in a 10-15% reduction in the cost of the overall system, as well as faster time-to-market.

The new production line can run continuously and automatically for a 10-hour day, allowing staff to “walk away” during processing. The only manual labor required is the initial set-up of the system up once at the start of a shift. This is drastically different than the client’s initial, rudimentary pilot line which required staff to actively manage manual, tedious tasks such as setting each card up with tweezers and loading materials for every run. In addition to reducing the risk of errors, the new system reduced the dependency on skilled staff, making it easier to hire and train users on the equipment. It also freed existing staff to focus on other, higher value tasks.

While the initial pilot line required two operators to actively manage the upstream and downstream systems for an entire 10-hour day to produce only 40 strips per day, the final production line was able to produce 42 strips per minute with no human intervention outside of the initial set-up. That throughput is an astounding 629 times greater than the initial pilot line.

The requirements document had a specified goal to process 1.5 cards per minute, which our team also exceeded. The final production line was able to process 2.1 cards per minute. The result was a throughput of 42 sensor strips per minute, 40% higher than the specified goal of 30 strips per minute.

The new, automated production line improved speed and throughput which drastically improved the cost per piece. The new cost per sensor is 11 times lower than what the initial pilot line could produce.  This cost reduction significantly improved profitability and scalability for the client.

Diagram showing the a/pH sensor card and manufacturing process in seven steps, from raw sensor film material to the finished sensor card, involving processes like dye absorption, heat drying, and packaging.

 

Monitoring and Inspection

The Ascential team also designed a vision inspection system to monitor production of components defined as critical to the process and accuracy of the final product. These vision systems provided the ability to inspect and reject products that did not conform to the setpoints and tolerances determined by the client.

Process monitoring was another key addition which enabled the system to run automatically and with minimal intervention from staff. Ascential’s software engineers designed an intuitive software program for tracking temperature, process parameters, and yield, enabling traceability by lot.

Finally, the team designed this dual zone system with employee safety at the forefront. The system utilized positive and negative pressure areas to protect the user from hazardous chemicals and vapors. If the device senses a problem, it will automatically shut down while venting hazardous vapor until the risk is eliminated.

According to the National Council on Compensation Insurance (NCCI), the average cost of a worker’s compensation claim is $41,757, a figure that can significantly affect production costs and productivity. Notably, 96.3% of cases involving exposure to harmful substances or environments resulted in at least one day of work absence, with the median affected worker missing a total of 9 days.

Conclusion

The Ascential team enhanced the design of this critical sensor film to deliver consistent performance and quality. Leveraging a deep bench of cross-functional experts in design, automation, and process development, our team not only achieved the specified product performance requirements but created an automated manufacturing process that reduced production costs and exceeded throughput expectations.

While the A/pH sensor is only one part of the manufacturer’s new dialysis system, its performance and quality are key factors in the delivery of advanced renal care and improved patient outcomes.

x

Reduction in per piece
(sensor) cost

%

Higher production rate than customer target, while improving product quality

Key Results

Exceeded the specified throughput requirement by 40%, achieving 2.1 cards (42 strips) per minute compared to the target of 1.5 cards (30 strips) per minute. The increased output significantly improved the client’s profitability.

Drastically increased production line throughput by 629 times, from 40 strips per 10-hour day to 42 strips per minute.

Increased speed and throughput reduced the cost per sensor by 11 times, making the product more profitable and scalable.

Improved worker safety with automatic shutdown and venting of hazardous vapors, providing a safer work environment and mitigating the risk of costly injuries and downtime.

Reduced build costs of the production equipment by 10-15% by using tested and proven components.