Cartridge FAQ · Shop the pen and cartridges
Put a 12-pin cartridge beside a 36-pin cartridge and the math seems obvious. One has three times as many needles. If what I want is firmer-looking skin, why wouldn’t I pick that one?
Here’s the catch: I can count needles by looking at a cartridge. I can’t count new collagen that way. After years of filming my own microneedling sessions, I wanted to look more closely at the part I usually show for just a few seconds before it goes on the pen.
Watch the Spa and Tell episode on microneedling cartridges.
What changes when you go from 12 to 36 pins?
Picture 12 dots on a small circle. Now put 36 dots inside that same circle. The second circle has three times as many dots per unit of area. But draw the second circle on a piece of paper three times the area of the first, and its average dot density is back where you started. That’s the detail the pin count leaves out: how much space those needles share.
A cartridge’s footprint, the spacing between its needles, their shape, and the pen driving them all matter. If every needle enters the skin on a stroke, 36 needles offer more potential punctures than 12. That still leaves the question I actually care about: how does the skin look once it has healed?
What about the “bed of nails” explanation?
There’s a reasonable argument for fewer needles, too. Imagine distributing the same force across a dozen points and then across three dozen. If the points share the load evenly, each gets less force in the second example. That helps explain why spacing might change how an array enters the skin. A powered pen adds other variables, including how its motor behaves when the needles meet resistance.
The microneedle mechanics study I looked at modeled how an array enters skin. It didn’t compare healed skin after treatments with two Dr. Pen cartridges. And the FDA filing for the MicroPen EVO describes penetration testing under load for that particular pen. I wouldn’t borrow those measurements for my M9 or assume the depth dial tells me exactly what happened in my skin.
What my own footage can tell me
I like how firm my face looks today. If you asked me which cartridge deserves the credit, though, I couldn’t point to one. My footage going back to 2018 gives me a record of my skin, but I’ve changed more than the tip of a pen over those years. Even my 30-minute check-in after my M9 session with Channel Pro Stem+ can only show what my skin looked like that day.
For a more useful comparison, I want a photo after recovery, taken at a similar angle in the same light, with the pen and cartridge written down. I can then say which session felt more comfortable or how long visible redness lasted for me. Neither observation measures collagen. In the research I reviewed for this episode, I didn’t find a head-to-head clinical trial strong enough to name a universal winner between 12 and 36 pins.
The detail I’d check before buying either one
Read the model name on the cartridge box. There’s a good example in the links below: Dr. Pen lists the 12-pin pack for the A9 and the 36-pin pack for the M9. If you own an M9, don’t assume the 12-pin pack fits because the brand matches.
This comparison covers conventional pens; radiofrequency microneedling also delivers energy. For microneedling that penetrates living skin, the FDA’s patient guidance recommends a trained health care provider and a fresh cartridge for every session, even on the same person. Infection and pigment changes are among the risks. A theory about needle count is no reason to turn up the depth or press harder.
When I look at those two packages now, my first question is which one belongs with the pen in my hand. My next is what evidence supports it for the change I’m hoping to see. The biggest number on the box can’t answer either one.
Microneedling cartridge FAQ
Is a 36-pin microneedling cartridge better than a 12-pin cartridge?
The count alone can’t tell you. A 36-pin tip has three times as many needles, but that doesn’t show how much collagen forms or what healed skin will look like.
What is the difference between needle count and needle density?
Count is the number of needles on the tip. Density is the number per unit of area. Two cartridges can have different counts but the same average density if their faces are different sizes.
Does a lower pin count always mean deeper penetration?
No. How far needles enter depends on the pen and cartridge working under load. The depth dial and the pin count alone don’t measure penetration in skin.
Which linked cartridges are made for the Dr. Pen M9?
The linked 36-pin pack is listed for the M9. The linked 12-pin pack is listed for the A9. Check the exact model on the package and in the device instructions.
Can I reuse my own microneedling cartridge?
The FDA advises using a new cartridge for every treatment session, including repeat sessions on the same person. Cleaning a used cartridge does not make it suitable for reuse.
Dr. Pen links and promo code
Use code KIMPRATT at Dr. Pen. These are affiliate links; I may earn a commission if you purchase through them.