Inside the Build: Surgical Energy

Featuring: Dan Friedrichs, Electrical Engineer, Carter Paulzine, Senior Electrical Engineer

“I feel like it’s a bit of almost social engineering to tease out with a customer how do I get you what you really want. What you’re telling me is maybe not what we need to put in the product.”

Welcome to Inside the Build, a podcast series that dives deep into how Forj Medical solves complex manufacturing challenges, told by the people whose knowledge, expertise, and ingenuity make Forj Medical the partner medtech companies trust when the technology is complex and the stakes are high.

What surgical energy actually is

Surgical energy is the term for any electromechanical medical device that delivers energy, primarily electrical, into tissue in order to remodel or change it in a way that treats a condition. Cutting, coagulating, ablating, changing how tissue conducts. A version of it is used in almost 80 percent of surgical procedures performed in the United States. If you have had your tonsils or your appendix out, it was used on you.

The physics is straightforward to describe. High-frequency electrical current is pushed through tissue, the tissue heats, and if that heat is directed precisely enough it produces a clinical result. Think about a 50-watt bulb. Put your hand on it and you feel warmth. Take that same 50 watts and focus it down to the edge of a blade or the tip of a probe and it creates a profound, local effect.

The technology is roughly 150 years old, which some people read as a technology that is finished. Radio transmission is about the same age.

How many applications there are

Take the head alone, which is not an especially complicated part of the body compared to the abdomen. Surgical energy is being used there to ablate brain tumors, to ablate the tissue that causes epileptic seizures, to restart tear production in patients with chronic dry eye, to reduce nasal turbinates so people can breathe, to interrupt nerves in the nasal passage for allergies that will not respond to other treatment, and to treat sleep apnea by treating the tongue or the palate. That is more than a dozen applications in one region, and the list keeps growing. Three or four genuinely new clinical applications arrive every year.

Carpal tunnel is a good example of what that looks like in practice. Standard treatment, when physical therapy does not work, is open surgery. The wrist is opened, the ligament compressing the nerve is cut or displaced, and the patient is out of commission for weeks. The device Forj worked on inserts a focused cutting element through a much smaller incision, applies a high-frequency field under the ligament to release the pressure on the nerve, and has the patient resting for a couple of days rather than recovering for a month. Nothing about the underlying physics was new. The clinical application was, and the value it created was significant.

Surgical energy is well suited to that kind of work for a practical reason. You could cut the ligament with a knife, but getting a knife into a physically restricted space, turning it on and off precisely, and controlling exactly how much you cut is a much harder problem than doing it with electrical energy.

The 45 degrees that turned out to be 39

A tablet-sized device Forj built heats a nerve and has a hard ceiling on how hot that nerve can get. The customer arrived with a number: 45 degrees C.

Controlling a temperature sounds like the simplest requirement on a device. Cruise control makes a useful comparison. Most people assume setting it to 60 means the car travels at exactly 60, when in reality the speedometer has its own accuracy, that accuracy shifts with something as ordinary as tire wear, and the control loop only knows to add throttle because the car has already drifted slower than the target.

Once the error budget, the tolerance analysis, and appropriate safety margins were worked through for the sensing technology the customer wanted to use, the honest answer was that the system needed to control to about 39 C to guarantee the nerve never exceeded 45. That drove significant changes to their clinical protocol and how the therapy is applied. Agreeing to 45 and sorting it out later would have been a bad outcome for everyone.

The complication behind that number is interference. There may be several other devices in the room while a physician is using this one, some of them delivering considerable energy into the same patient. Keeping a very small temperature measurement stable through that is hundreds of hours of specialized engineering behind a requirement that reads like one line.

The social engineering part

A lot of this work is less about circuits than about getting to what the customer actually needs. What the physician needs is not what the marketing team needs, which is not what the environment the device will live in demands. Teasing that apart early is one of the most valuable things a development partner does.

Some of it is charming. One customer specified tasteful, moody lighting on a surgical energy system, and that is not a hard request to accommodate. But every request carries a development cost, a schedule, and a question worth asking out loud. There are surgical staplers on the market with Bluetooth, and someone decided that was worth it. The useful version of the conversation is about priority: are we getting to a minimum viable product for a clinical study quickly so you can learn, or are we building the polished commercial product for a launch you have already scheduled.

Some of it is less obvious. One of the smallest surgical energy devices Forj has built has a full computer running Linux inside it. Every IT department in the world tells employees not to plug found USB sticks into their machines. So when a customer wants a USB port on the back of a medical device, the real question is what it takes to make that safe for the patient, and whether shipping the unit back for service updates is the cheaper and better answer.

Low volume, high impact

Forj builds some products in the millions of units per year and others in the tens. Surgical energy tends to sit at the low-volume end, which is easy to mistake for low impact.

Run the math on a single system. A console sitting in a clinic treating eight patients a day, 250 days a year, across a ten-year product life reaches tens of thousands of patients. That changes the engineering calculus. Automation and unit-cost optimization matter less. Serviceability, longevity, and getting the therapy right matter more.

Designing for a decade

These devices can stay in the field for ten years or more, which is a long time in a supply chain driven by consumer electronics life cycles. Displays are the recurring problem.

On a current program the customer selected a screen they liked for entirely valid reasons, from a vendor with no track record on longevity, using a flex tail connector rather than the wired connector the team would normally expect. The mitigation was to put an unused footprint for a conventional wired connector on the circuit board. It costs almost nothing now. If the screen has to be swapped seven years from now, the replacement is far more likely to use a wired connector, and the footprint avoids a board respin plus the validation, verification, and regression work behind it.

That is the pattern worth noticing. It is easy to design something that works and to build a few prototypes. If the material cannot be sourced at the volume and duration the product needs, there is still no product.

Design and build in the same building

Forj engineers who design new products also spend time in new product introduction, physically building them. That combination is what closes the loop fast. An engineer who assembles the first revision of a board into a product finds the mistakes immediately, and because two or three board revisions are already planned into the schedule, those mistakes get corrected on Rev 2 rather than surviving into production.

The proximity is not exotic, but it is not industry standard either. Plenty of large contract manufacturers design in one state and build in another, or on another continent, and never get a clean look at where the process hiccups are. Here, the person who designed the board can walk over, watch it get assembled, and hear directly whether they did a good job. They are eating lunch next to that operator later the same day.

The same knowledge applies to devices Forj did not design. Customers regularly bring in products built elsewhere and ask for manufacturability improvements. The best time to have that conversation is at the beginning of the program. The second best time is now.

What’s next

The direction of the field is toward devices that solve more of the clinical problem themselves. Less of a generic tool the physician has to figure out how to apply, more of a complete solution that interprets what is happening and knows when the procedure is done. The carpal tunnel device did exactly that. When a physician says they just press the button and it goes, that is the product working correctly. You do not want to ask a carpenter how their tools work and get a lecture. You want to drive nails.

The technology getting the most attention right now is pulsed field ablation, which uses very high voltages to manipulate cells directly rather than heating tissue. Interest is strongest in cardiac electrophysiology, with customers also exploring cancer treatment and drug delivery. From an engineering standpoint it is a genuinely new problem: voltages roughly an order of magnitude higher than typical, plus complicated pulse timing and a set of technical challenges nobody has a decade of practice solving. This has been Inside the Build, a podcast series by Forj Medical, where we’re shaping the future of life-saving devices, one build at a time. Thank you for listening. For more information, visit us at forjmedical.com.