The ability to print sensors has many benefits, including lower cost and faster production output. In particular, screenprinting is prominently used, with one major example being glucose test strips for diabetes patients. Now, as the world battles COVID-19, pharmaceutical companies around the world are looking to meet the need for millions of test strips.

SPGPrints B.V. is among the printing equipment specialists who have adapted its experience in rotary screen printing for biosensors to working on COVID-19 cures. Due to the close collaboration between SPGPrints and its client, millions of test strips are expected to be produced in the upcoming months.

Hank Guitjens, commercial manager label & industrial printing for SPGPrints B.V., noted that SPGPrints started to supply its rotary screen solutions to pharmaceutical companies in the biosensor industry about 10 years ago, and these are being successfully used to produce COVID-19 tests.

Guitjens noted that rotary screen printing is ideal for producing biosensor strips. A foil on a roll is the starting point and runs through several RSI units, each of which has a hot air dryer. In each RSI unit, a 100% electroformed nickel mesh is rotating and applies a layer of ink or solvent. Several layers on top of each other create a strip. All is done in a roll-to-roll process.

Guitjens noted that SPGPrints was invited by an international pharmaceutical company to produce a COVID-19 rapid test that could use the patient’s saliva to quickly indicate if a patient suffered from COVID-19. One key was to achieve high levels of accuracy.

The film used for the test strips must be printed so that it can absorb the body fluid and provide the conditions for the reagent to react with the body fluid.

“The basic is an RSI Unit (Rotary Screen Integration),” he said. “The width of the printing process starts at 250mm and goes up to 1400 mm. A rotating mesh is needed to apply the ink, solvent or pasta on any substrate. The advantage is that you can apply a layer of a minimum of 7 microns and a maximum of 250 microns.

“Depending on the type of mesh, we can control that process in a continuous process. This can be done on an existing production line or a third party production line. We can create a custom-made printing line for any client around the world,” Guitjens added.

Guitjens said that there were challenges in printing biosensors.

“The process contains four RSI units in one line, and all have to print in register with a very narrow tolerance,” he noted. “The challenge is the hot air which creates the temperature difference which we are having to control.”

He noted that the startup phase was successful, and a yield was achieved above expectation within weeks. This enabled the pharmaceutical company to reach ideal production levels within weeks after the new system had been delivered.

Guitjens sees plenty of opportunities for rotary screen printing for printed electronics.

“SPGPrints sees a growing demand in screenprinting of printed electronics, like RFID tags, biosensors, electronic circuits, printed batteries and flexible solar panels,” he added. “While global volumes are growing, a faster production process is required and there comes rotary screen printing around the corner. With the same accuracy, more output can be achieved while the process continues.”

“As said volumes of end products are going up and current screenprinting cannot go faster, rotary screen printing is the next level with higher results. It is used more and more in the field of printed electronics,” Guitjens added.