Making a mark: Bonding RFID tags to surgical instruments – Med-Tech Innovation

Peter Swanson, managing director of adhesives specialist Intertronics, discusses the considerations for manufacturers bonding RFID sensors to surgical instruments.

A typical hospital uses hundreds of medical instruments across its operating theatres and emergency rooms each day. Hospital teams must therefore manage a precise assortment of tools during procedures to keep track of equipment, to ensure none are misplaced and to keep patients safe. Historically, monitoring the availability and location of tools was performed manually by hospital teams, who would record serial numbers or scan barcodes. However, this is a time-consuming task that is prone to human error. As regulations become more stringent, the assigning of unique identifiers to medical instruments that enable their management has become more important, as has the improvement of the systems used to management.

To improve how surgical tools are managed, many hospitals are now opting for digital surgical instrument tracking systems, such as those based on RFID. These systems can improve patient safety, as well as uplift hospital efficiency, by streamlining surgical processes and ensuring the correct tools are available. An RFID system enables surgical teams to monitor instrument availability, check sterilisation status, and better manage inventory. They are easier and quicker to scan than barcode tagged devices, as the user does not have to exactly align the tag with the reader.

Becky Moyce

According to Fact. MR and reported in Bloomberg, the global surgical instrument tracking market is expected to reach $1,294.89 million in 2023, exhibiting a CAGR of 18% from 2022 to 2032.  As the market grows, many manufacturers are looking to start RFID tagging their instruments, or scale up their production of RFID tagged instruments. This can bring some design and manufacturing challenges.

Manufacturing RFID tagged instruments

The adhesive used to bond RFID chips must form extremely strong bonds to stainless steel and other materials that instruments are made from, to ensure the tag remains in place throughout the product’s lifetime. It is critical the materials used can tolerate the environmental stresses the tool will be exposed, such as high heat, humidity, and chemical exposure. One significant environmental stress surgical tools must be able to withstand is sterilisation cycles, such as autoclaving, STERRAD Hydrogen Peroxide Plasma, ethylene oxide, E-beam, and gamma. Manufacturers must therefore choose a material that is robust enough to withstand the demands of the healthcare environment, resistant to sterilisation cycles, and meets certifications like ISO 10993-5.

While there are formulated one- and two- part epoxies on the market for the bonding, coating, and encapsulating of medical devices and RFIDs, these carry limitations. Epoxies typically require specialised mixing systems, have long cure times (up to 60 minutes), short pot life, and may require the use of heat curing equipment. As well as the process disadvantages, the materials have relatively low flexibility and impact resistance, and may require purge cycles that could result in hazardous waste.

Addressing the challenges

To address the process trade-offs associated with epoxies, a new versatile UV/LED curable adhesive has been developed that can withstand 100+ cycles of autoclave and plasma processes. The material, Dymax 1040-M, exhibits extremely low water absorption (0.5%). This makes it particularly interesting for bonding RFID chips, sensors, and other electronic components found on medical devices, tools, and vials where moisture ingression may be of concern. It features exceptional bond strength to a variety of substrates including stainless steel, aluminium, glass, PP/PE, and PCBs. It is compliant with ISO 10993-5 cytotoxicity and is formulated without IBOA (a known skin irritant).

Compared with epoxies, one-component light-curable adhesives can greatly improve manufacturing productivity, throughput, and efficiency — crucial at a period of high market growth, where manufacturers may be looking to scale up operations. UV curing materials offer fast “on demand” curing (typically in seconds) when exposed to the correct wavelength of UV light, reducing work in progress, increasing throughput, and reducing costs. A 100% solids, 100% solvent-free, single part formulation simplifies and reduces cost of handling, processing, and dispensing, while minimising environmental impact and improving worker safety.

Also, UV light curing systems help achieve process reliability, repeatability, and validation. UV curable materials are simple to dispense from a simple syringe using anything from time/pressure control, right up to sophisticated volumetric positive displacement pumps. For example, the preeflow eco-PEN, which offers precise, process-stable dispensing as small as 1 μl, and boasts an accuracy of ±1%, >99% of the time. UV curing adhesive processes can be readily automated with a benchtop or gantry robot to improve productivity and remove inconsistencies.

As the market for RFID tagged instruments grows, to improve hospital efficiency and keep patients safe from RISs, the adoption of a UV LED curing adhesive can bring manufacturers process and technical benefits. For best results, work with an adhesives partner who can build a process where all the equipment works together optimally, as this will help deliver efficiency and return on investment.