Nitinol vs nylon thread: which is better? | The maker found reasons to combine them [OK Prostate Chip]

This page is based on entries from "ok-lab's diary" (https://ok-lab.hatenablog.com/), the Japanese development diary written by Mr. Okada, founder of OK Lab, a small company in Japan (Okada Comfortable Life Laboratory). Only the entries about "nitinol vs nylon thread" are summarized here, in order of publication. Past prices and sizes are as written at the time. Current prices come from the official product list (retrieved September 4, 2026). Quotations are translated from Japanese.

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Note: This page is a personal reading log by someone with no connection to the maker or the seller. It reflects the source entries as of their publication dates and makes no guarantee of accuracy or safety. The product is not a medical device; talk to a doctor about any health decision. Check the official site for current information. This page contains advertising.

In short

Mr. Okada describes nitinol (metal that returns toward its earlier shape) as springier than nylon, with no breakage guarantee.

He later favored nitinol inside the body and nylon near the penis tip or outside.

The current list does not confirm the diary’s custom nitinol thread configurations.

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About this product

The OK Prostate Chip is a small device that is placed in the urethra (the urine passage) so that it acts on the prostate; the maker sells it in several shapes, sizes and materials. It is made and sold by OK Lab (Okada Comfortable Life Laboratory), a small company in Japan, through its own online store, and prices are in Japanese yen (JPY). The maker's development diary, "ok-lab's diary", is written in Japanese. This page is an English summary of it, and every quotation is translated. OK Lab ships internationally, so readers outside Japan can order (see "Buying from outside Japan" below). Product names on this page are plain-English descriptions. The official Japanese product name is shown once in the product table so you can find the same item in the store.

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Before you read: key terms

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What happens: nitinol vs nylon thread

The OK Prostate Chip is a device placed in the urethra (urine passage) to act on the prostate. Nylon and nitinol threads connect the main chip to smaller attachments and can continue toward the outside of the body. These entries compare how the threads bend, retain their shape, and behave as parts of those assemblies. They also form part of the retrieval system.

Thinner nitinol wire led to a flexible extension containing both materials

In an entry published in April 2025, Mr. Okada found 0.2mm wire almost as flexible as thread, and thinner than 0.24mm nylon. His prototype retained its straight shape after being released from a bend. He put both materials inside a tube-covered extension, intending nylon to preserve its function if the wire broke.

The published prices, tax excluded, were ¥3,000 (about $19 at ¥156 = $1, rate as of 2026-09-04) for the 2.5mm tube version and ¥4,000 (about $26 at ¥156 = $1, rate as of 2026-09-04) for the 1mm version, each up to 10cm. The wider version was also offered up to 30cm, with a further ¥1,000 (about $6 at ¥156 = $1, rate as of 2026-09-04) charge. Mr. Okada proposes the combined core as reassurance for people concerned about thin wire breaking.

(Source: ok-lab's diary, published April 2025)
https://ok-lab.hatenablog.com/entry/2025/04/12/122910

Nitinol thread launched after a short test, with compatibility limits

In an entry published in August 2025, Mr. Okada reports secure connections through the chip’s thread holes. He also reports no problems during his own 3-day test with the device continuously in place. He then announced nylon and nitinol connection options for blue resin, stainless-steel, and ceramic chips.

The published change from nylon to nitinol cost ¥2,000 (about $13 at ¥156 = $1, rate as of 2026-09-04) tax excluded, with a maximum thread length of 35cm. He describes about 2mm of raised thread at a connection, compared with about 1mm for nylon. Mr. Okada excludes the blue safety attachment because its required bend would put excessive strain on the nitinol.

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/09/122924

Mr. Okada found nitinol thread recovered its shape more readily than nylon

In another part of the entry published in August 2025, Mr. Okada compares 0.2mm nitinol with 0.24mm nylon. He describes nitinol as springier and able to recover its shape unless bent beyond its limit. He says nylon has less stiffness and does not fully recover after bending.

His standard at that point used two nitinol strands, with the remaining strand intended as backup if one broke. Mr. Okada’s safety principle assumes that either material can break.

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/09/122924

Mr. Okada proposed finer nitinol thread to balance flexibility and stiffness

In a later entry published in August 2025, Mr. Okada describes nylon folding inside the urethra, becoming slack, and disappearing from view. He also says loose nylon can advance ahead of the chip and become tangled. His proposed standard used 4 strands of 0.15mm nitinol, with a stated breaking force of 9Kgf.

He compares that with 8Kgf for 2 strands of 0.2mm wire. His 0.1mm prototype lacked the stiffness needed for a pushing effect, while an 8-strand version would be substantially more expensive. Mr. Okada therefore proposes the intermediate thickness as his standard.

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/23/122935

Mr. Okada describes different weaknesses in nylon thread and nitinol

In an entry published in August 2025, Mr. Okada describes separate nylon and 0.1mm nitinol threads attached to a semi-long ceramic chip. He says nylon is vulnerable to heat and blades, while nitinol is vulnerable to strong compression. At this thickness, he found the materials similarly soft to the touch.

The published ceramic connection charge was ¥1,000 (about $6 at ¥156 = $1, rate as of 2026-09-04) tax excluded, plus ¥500 (about $3 at ¥156 = $1, rate as of 2026-09-04) tax excluded per nitinol strand up to 35cm. Mr. Okada’s stated precaution is protective treatment of the nitinol ends.

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/30/122943

Coated nitinol thread followed concerns about nickel exposure from cut ends

In an entry published in September 2025, Mr. Okada reports a supplier’s warning that cut wire ends could release nickel. He announced a policy against offering nitinol products involving direct metal contact with skin. His thin silicone coating (a rubber covering) kept coated wire at 0.3mm or less, while he found its flexibility largely unchanged.

He also reports less accessory slippage than with nylon, because the coating increased friction. Thin coating carried no extra charge; thicker coating cost ¥500 (about $3 at ¥156 = $1, rate as of 2026-09-04) tax excluded per 5cm. Mr. Okada suggests thicker coating for sensitive contact areas, while noting that thick sections cannot pass through accessory holes.

(Source: ok-lab's diary, published September 2025)
https://ok-lab.hatenablog.com/entry/2025/09/06/122911

Mr. Okada’s jointed nitinol thread prototypes could still slip out

In an entry published in November 2025, Mr. Okada describes a jointed assembly (connected, resin-covered sections) containing both materials. It used two 0.15mm nitinol strands and two nylon strands in a structure about 4mm across. He regarded the mixed core as useful because the materials had different weaknesses.

However, he reports poor ability to stay in place without additional friction from other parts. Mr. Okada presents the assembly as an option for people who find earlier designs difficult to position.

(Source: ok-lab's diary, published November 2025)
https://ok-lab.hatenablog.com/entry/2025/11/29/122908

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The maker's answer to nitinol vs nylon thread

Mr. Okada’s proposals depend on breakage concerns, the thread’s position, and whether metal is covered.

Mr. Okada advises delaying nitinol thread when breakage concerns remain

In an entry published in August 2025, Mr. Okada says durability depends partly on the conditions of use. He does not guarantee that either nylon or nitinol will never break. He also acknowledges that both strands could break together.

For people worried about this, he offers two responses. Mr. Okada advises waiting before adopting nitinol, or considering the more expensive tube-covered extension containing both nylon and nitinol.

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/09/122924

Nitinol thread inside and nylon outside became the maker’s preferred combination

In an entry published in September 2025, Mr. Okada favors nitinol internally and nylon outside the body or near the penis tip. He finds nylon’s willingness to stay bent useful outside, while nitinol helps preserve spacing between connected chips.

The published additions were tax excluded and depended on nitinol length and strand count. Up to 10cm, 2 strands cost ¥1,500 (about $10 at ¥156 = $1, rate as of 2026-09-04) extra and 4 cost ¥2,000 (about $13 at ¥156 = $1, rate as of 2026-09-04) extra. Up to 20cm, these were ¥2,000 (about $13 at ¥156 = $1, rate as of 2026-09-04) and ¥2,500 (about $16 at ¥156 = $1, rate as of 2026-09-04); up to 30cm, ¥2,500 (about $16 at ¥156 = $1, rate as of 2026-09-04) and ¥3,000 (about $19 at ¥156 = $1, rate as of 2026-09-04), respectively. Mr. Okada recommends combining the materials according to their position.

(Source: ok-lab's diary, published September 2025)
https://ok-lab.hatenablog.com/entry/2025/09/13/122925

Nitinol thread with multiple screw attachments received a different covering policy

In an entry published in November 2025, Mr. Okada permits uncovered nitinol in a design with multiple screw attachments. He believes those attachments reduce contact between wire and the urethral lining. This later allowance concerns that particular arrangement.

He describes two strands as softer to handle and four as preferable when breakage is a concern. Mr. Okada still recommends tube covers for anyone concerned about metal allergy.

(Source: ok-lab's diary, published November 2025)
https://ok-lab.hatenablog.com/entry/2025/11/01/122937

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How nitinol vs nylon thread changed over time

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OK Prostate Chip products related to nitinol vs nylon thread

The current list includes a ceramic base chip and an accessory mentioned in the experiments; custom thread specifications remain unconfirmed.

Products that appear in these entries

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/09/122924

(Source: ok-lab's diary, published August 2025)
https://ok-lab.hatenablog.com/entry/2025/08/30/122943

Products the diary mentioned as alternatives

The diary names no alternative.

The entries also describe custom tube-covered extensions, joined-thread builds, integrated loops, jointed hybrid assemblies, and a four-thread stainless-steel assembly. No matching product can be confirmed on the current list.

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Common worries about nitinol vs nylon thread

The recorded customer requests concern loop design and thread compatibility, rather than a direct choice between materials.

"Can a nitinol wire loop be easier to catch?"

In an entry published in April 2025, a customer requested a double end loop on a custom wire extension. Mr. Okada made the requested structure and interpreted the request as a concern about dependable retrieval. He believed the doubled loop would be easier to catch than a single loop.

The diary does not record the customer’s subsequent experience. Mr. Okada offers the double-loop option for an additional ¥1,000 (about $6 at ¥156 = $1, rate as of 2026-09-04) tax excluded.

(Source: ok-lab's diary, published April 2025)
https://ok-lab.hatenablog.com/entry/2025/04/12/122910

"Can nylon thread form a loop attached to the chip?"

In an entry published in October 2025, a customer requested a nylon loop joined directly to a custom device. Mr. Okada made it and found that the whole loop largely recovered its original shape after bending. The diary does not record the customer’s experience in use.

The additions were ¥1,000 (about $6 at ¥156 = $1, rate as of 2026-09-04) up to 10cm, ¥1,500 (about $10 at ¥156 = $1, rate as of 2026-09-04) up to 20cm, and ¥3,000 (about $19 at ¥156 = $1, rate as of 2026-09-04) up to 30cm, tax excluded. Separate accessories were difficult to fit. Mr. Okada recommends an integrated stopper when one is needed.

(Source: ok-lab's diary, published October 2025)
https://ok-lab.hatenablog.com/entry/2025/10/25/122907

"Can four nylon threads pass through the screw attachment?"

In an entry published in March 2026, a customer requested four nylon threads with a stainless-steel chip and screw attachment. Mr. Okada initially expected some threads to remain outside the attachment. His completed assembly accommodated all four through it.

He explains that nylon could buckle against roughness inside the holes, while nitinol retained enough stiffness to pass. The diary does not record how the completed assembly felt in use.

(Source: ok-lab's diary, published March 2026)
https://ok-lab.hatenablog.com/entry/2026/03/28/122908

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Buying from outside Japan

OK Lab ships internationally to countries covered by Japan Post's EMS courier service. Overseas orders are paid in advance by PayPal. Each order carries a ¥400 (about $3 at ¥156 = $1, rate as of 2026-09-04) handling fee, and EMS shipping is charged on top. These terms come from OK Lab's official sales-terms page (written here as plain text, not a link: ok-lab.net/docs/law), checked on September 7, 2026; confirm them on the official store before you order, because they can change.

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Summary of this article

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Source: ok-lab's diary (Okada Comfortable Life Laboratory). The original entries are in Japanese; quotations on this page are translated. Photos and videos are on the original entries.