PCBA Development Essentials for Minimally Invasive Medical Devices

You may have heard that the human body is a temple and should be treated as such. This simple directive inspires some people to take another well-known adage, “no pain no gain,” far too seriously. Running the Boston Marathon, climbing Mount Everest, or swimming the English Channel are all examples of the human body’s ability to perform great feats; however, they are meant to be lifetime achievements and not routine exercises. But while proper nourishment and regular exercise can contribute to better health, the unfortunate truth is that no matter how fit you are, at some point, your body will decline, and you will likely need care that includes the use of a biomedical device to either preserve or improve your health.Minimally invasive medical device

Surgeon utilizing a minimally invasive medical device

Biomedical devices are a subset of medical devices (which include all devices that are typically used to assist in the healthcare of a patient) that directly interact with the body in some way. This can range from simple devices such as tongue depressors to invasive medical devices like implants. Between these two extremes lies a group of medical devices that are considered to be minimally invasive. Many of these devices are comprised of electronics and PCBAs that enable them to perform advanced functions. For example, converting an optical image into an electronic signal for processing and providing data to a medical professional. Before discussing the essentials for developing these PCBAs, let’s clearly distinguish between invasive and minimally invasive medical devices.

Minimally Invasive Versus Invasive Medical Devices

What is the difference between invasive and minimally invasive medical devices? Actually, they are similar in that both types are intended to be used for some function within the body. Specifically, minimally invasive devices can be defined as:

Medical instruments that require insertion into the body to perform their intended function but do not directly impact the function of internal organs are considered minimally invasive medical devices.

Invasive medical procedures, on the other hand, typically interact directly with internal organs and may influence their function. In fact, implants, which are invasive devices assist with functionality or may replace internal organs altogether.

Minimally invasive devices are typically used to take measurements, acquire samples and assist during surgery. The most common types of minimally invasive medical devices used for these functions are surgical robots and endoscopic devices. The latter which are primarily used for inspection includes a large number of devices, some of which are listed below, along with what organs are used for.

Minimally Invasive Medical Devices used for Endoscopy

  • Arthroscope: Joints
  • Bronchoscope: Esophagus and lung
  • Colonoscope: Colon and bowel
  • Cystourethroscope: Bladder and urethra
  • Cystoscope: Bladder
  • Duodenoscope: Small intestine
  • Esophagogastroduodenoscope: Esophagus, stomach and small intestine
  • Gastroscope: Stomach
  • Hysteroscope: Womb
  • Laparoscope: Abdomen
  • Laryngoscope: Larynx
  • Proctosigmoidoscope: Lower part of the large intestine
  • Sigmoidoscope: Large intestine
  • Thoracoscope: Thorax
  • Ureteroscope: Pelvis and ureter

The list above is not exhaustive, but it does give a good indication of how common endoscopic devices are. Traditionally, having an endoscopic procedure was a bit trying for patients as they were required to endure a long cable inserted into their bodies with a camera on the end. However, this technology has advanced and today there are endoscopy capsules, as shown in the figure below.

Typical endoscopic capsule

Block diagram of endoscopic capsule [1]

Endoscopy capsules function autonomously, taking pictures as they proceed through the gastrointestinal tract. The images are converted into electronic signals by internal PCBAs and transmitted wirelessly to a receiver outside the body. The data can then be analyzed by a computer program. These boards are obviously quite small and typically have non-standard form factors, which requires that their development process be targeted toward these and other special considerations discussed in the next section.

Minimally Invasive Medical Devices Development Objectives

Medical devices, whether invasive or minimally invasive, are used internally (i.e. within the patient’s body). Therefore, safety has to be the primary concern throughout the development process. However, there are other objectives, as listed below, for minimally invasive medical device PCBA development that you should include to ensure your board meets its quality and reliability requirements.

Optimizing PCBA Development for Minimally Invasive Medical Devices

  • Employ electrical protection

This is a greater concern for devices; such as endoscopic capsules, where the board will be inside the body. In these cases, it is critical to limit any electrical discharges that may cause damage and lead to leakage into the patient.

  • Design for electromagnetic compatibility

As signal transmission, whether by cable or wirelessly is required, you should employ design techniques to limit radiation or emission that may interfere with signal integrity.

  • Follow good HMI and/or HDMI layout guidelines

The boards used in endoscopic devices are very small. This means that traces will likely be quite close together. HMI trace routing is effective in these situations. Additionally, it is advisable to use HDMI standards for video feeds.

  • Make advantageous utilization of flex and rigid-flex technology

This is especially pertinent for endoscopy where cabling is used. Flexible boards and traces enable greater mobility within the body for better inspection and more precision for surgical procedures.

Just as for invasive medical devices, applying good PCBA development guidelines, including quality management and risk analysis, should be followed. Minimally invasive medical devices are a special class of invasive devices that are utilized for a wide range of medical procedures. The benefits of using these devices for patients include less pain, low risk of infection, shorter hospital stays and minimal or no incisions. Therefore, their utilization is likely to only increase.

Tempo's Advanced Custom PCB Manufacturing Service for Complex Medical Systems Development
  • Works with 4 of the top 10 medical devices manufacturing companies.
  • ISO-9001, IPC-600 and IPC-610 commitment to quality certifications.
  • Accurate quote in less than a day.
  • DFM support from Day 1 of design.
  • Fastest turnkey PCB manufacturing in the industry.
  • Rigid, rigid-flex and flex board capabilities for wearables and embedded biosystems.
  • Custom automated BOM verification tool.
  • Sources components from the most reputable suppliers in the industry.
  • Software-driven robotics assembly.
  • Standard quality testing, including X-ray and inline AOI.
  • Superior open, transparent PCB manufacturing experience.

Tempo Automation, the industry leader for fast, complex manufacturing or low volume and prototype PCBAs, can help you meet the requirements for developing boards for these special devices.

And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.

If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on CAD files or how to incorporate your design into a CAD format, contact us.

[1] Image from Koprowski, R. Overview of technical solutions and assessment of clinical usefulness of capsule endoscopy. BioMed Eng OnLine 14, 111 (2015). https://doi.org/10.1186/s12938-015-0108-3. Used by permission from https://creativecommons.org/licenses/by/4.0/.

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