The benefits and applications of photochemical etching for medical technology

Photochemical etching offers high precision and fast production for specialty medical device manufacturers.

By Jace Harwood, Fotofab

Complex, precision metal components are found in a variety of medical industry applications, and the demand for these parts is increasing with the medical technology industry’s rapid advancements. With robotics and AI technology’s increased use in medical technology environments, the need for highly specified and calibrated parts will only become greater and more urgent.

Acknowledging this evolution, traditional manufacturing processes are not always the best-suited solution. Longstanding manufacturing methods such as stamping, computer numerical control (CNC) machining and laser cutting can negatively affect the metal’s integrity and compromise the performance of the parts needed for health care solutions.

One of the leading solutions — photochemical etching — has proven to be an ideal manufacturing process that fits specific requirements of the medical industry’s advanced technologies.

Photochemical etching and its history

Photochemical etching is a high-precision, fast production process used to equip health care professionals with the tools needed to keep patients safe and healthy. The process can create intricate and detailed patterns or designs from sheet metal such as stainless steel, nickel alloys, copper alloys and titanium. It is a subtractive metal fabrication alternative to other traditional manufacturing processes that produce critical parts for the medical industry. The technique falls within the rapid prototyping classification, or the fast fabrication of a physical part, model or assembly.

In its earliest form, photochemical etching was used by ancient Egyptians in 2500 BCE to create jewelry for nobility. Around the first century CE, alkaline etchants were introduced, and during the mid-1500s, erosive chemicals and compounds like vinegar, sodium and charcoal were used to create intricate designs in armor, weaponry and furniture without damaging the integrity of the material.

During the Industrial Revolution, newspapers and periodicals used photochemical etching to create printing plates. Around the 1960s, the creation of photoresist film was promoted by Kodak with more complex chemicals and stronger materials. Since then, several photochemical etching companies have emerged and identified ways they could service the health care industry through high quality advanced manufacturing solutions.

How photochemical etching works

Photochemical etching is a photo-lithographic process where a high-tech digital imaging machine shines UV light in defined areas, exposing parts of the sheet of metal that has first been cleaned and laminated with photoresist, which are polymeric materials that transfer micro- and nanoscale patterns to a substrate. The sheet is then developed to wash away the unexposed photoresist, leaving a very precise mask of hardened photoresist behind. This patterned sheet is fed through concentrated etchants which dissolve the exposed material, resulting in exact-to-print parts once the remaining photoresist is removed.

The process reliably produces intricate, close-tolerance patterns in a variety of flat, metal materials. It is a preferred method to other traditional processes, as photochemical etching eliminates the heat transfer issue of laser cutting and the physical impact force of mechanical techniques such as stamping.

Benefits of photochemical etching

Photochemical etching answers the demand for low-cost, burr-free parts for medical technology,making parts safer for handling. Setup and tooling costs are low, as well as design change costs since only the artwork file is altered with no further tooling required. Photochemical etching has a burr-free process, meaning there are no unwanted raised edges or small pieces of material that could prove dangerous for handling. There is no added time or cost to remove burrrs, making production timelier and more cost efficient.

Photochemical etching allows for increased accuracy and does not compromise the material. Extremely thin metal can easily be etched without distortion, and magnetically soft materials can be fabricated and retain optimum permeability. The process results in greater precision while maintaining the metal’s original grain structure and physical characteristics. Through state-of-the-art digital imaging machines, specialty manufacturers can precisely map designs onto the metal sheets and eliminate variations, so production remains consistent part to part and sheet to sheet.

Photochemical etching lets specialty manufacturers meet high volume demands in a quick turnaround. Initial quantities of newly designed parts can be produced on short notice, sometimes within a few hours after the design has been conceived. As a form of rapid prototyping, specialty manufacturers etch various components for devices that diagnose, treat and repair life-threatening issues quicker and more efficiently.

Photochemical etching in practice

Photochemical etching is a widely applicable and diverse method to provide medical practitioners with real world solutions. One way we’ve used photochemical etching in a medical application is by developing stainless steel screens for organizations producing biotech solutions. The screen is used to filter out plastic particles that are used to grow cells more effectively. The metal mesh is a flat surface, as opposed to fabric mesh that has a weave pattern creating crevasses, leading to potential build up, blockages and contamination.

We also used photochemical etching to produce electrodes from beryllium copper for ablation devices, used to remove tissue in various medical applications. The electrodes were custom designed to fit perfectly into an existing device, therefore replacing outdated parts without affecting the rest of the application. Photochemical etching is also ideal for biocompatible metals like stainless steel 316 and titanium. One customer has designed an etched metal part that assists in orthopedic wrist surgeries, while another has created surgical snares to thread tendons for placement.

The future of photochemical etching

The health care industry continues to rapidly evolve, and it is imperative that engineers finetune their practices to meet this demand for specialty manufactured medical applications. As medical device manufacturers consider photochemical etching’s advantages and challenges, they should look for ways to integrate it into practice to develop specialty parts with speed, accuracy and cost-efficiency.

Jace Harwood is the chemical process engineer at Fotofab. With 20 years of experience in the manufacturing sector, Jace has a chemical engineering degree from Montana State University – Bozeman and a diverse background working as a process engineer and continual improvement leader in the food and specialty chemical industries and later as an operational excellence site manager in pharmaceuticals.

How to submit a contribution to MDO

The opinions expressed in this blog post are the author’s only and do not necessarily reflect those of Medical Design & Outsourcing or its employees.