Portable and Handheld Ultrasound Fleets (2026): What Breaks, What Can Still Be Repaired, and How to Budget Service

Two classes, not one "portable" line

Purchasing and asset registers often file every battery-powered scanner under one heading. For service planning the heading hides the decision that matters. Many handheld probes combine imaging electronics and a battery in a sealed housing and depend on a mobile app. Others differ materially: Lumify draws power from its host and legacy Clarius HD uses a removable battery. The analytical handheld group also includes integrated-display pocket and tablet devices. Compact portable systems generally expose more separately serviceable components, but exact model instructions determine battery access, parts availability and qualified repair routes. ⁴⁶⁸

Those construction differences decide what happens after a fault. When a sealed handheld stops holding charge, the route is a warranty claim, a manufacturer battery service where one exists, or a replacement. For a compact system that stops powering up, qualified fault isolation can distinguish the battery pack, adapter, power conversion board, dock and other causes. The same word, "portable", covers a device that is serviced as a unit and a device that is serviced as an assembly of parts.

Cart-system habits fit the second class and mislead on the first. The cart playbook assumes long lives extended by board-level repair, probe repair and parts supply. Applied indiscriminately to a handheld, that playbook can overlook manufacturer exchange terms, battery limitations and host-device costs. Applied in reverse, treating compact systems as disposable consumer electronics retires equipment whose faults resolve to replaceable parts.

Handhelds moved from a curiosity to one clearance in eight

The US clearance record is the cleanest public series on how fast the handheld class has grown. We analysed the FDA 510(k) database export dated July 22, 2026, restricted to the diagnostic ultrasound imaging product codes IYN, IYO and ITX and the home-use imaging code SGJ, and classified each decision from 2010 to June 29, 2026 by device name and applicant. ¹

Across the period there are 1,119 decisions under those codes. After excluding 96 records for products that share the codes without being general imaging systems (bladder scanners, ophthalmic instruments, elastography devices, intravascular catheters and several multi-system bundles), 1,023 records remain. Of these, 72 are handheld probes, 106 are compact portable systems identified by a form-factor word or a known portable model name, and 845 are other systems, transducers and accessories. The compact count is a lower bound because a laptop system whose clearance name carries no form-factor word falls into the "other" group. ¹

Handheld clearances were zero in 2010, 2011 and 2012 and one in each of 2013 and 2014, while total in-scope clearances ran between 49 and 70 a year. From 2015 the count moved to between three and six a year, and from 2020 to between four and eleven: 4 in 2020, 11 in 2021, 7 in 2022, 6 in 2023, 9 in 2024, 8 in 2025 and 4 in the first half of 2026. Total in-scope clearances stayed between 55 and 80 a year from 2015 to 2025, so the change is composition, not volume. ¹

More than one in eight recent clearances is a handheld. Adding compact portables, between one in four and one in five clearances since 2020 describes a device that runs on a battery. Sixty-two of the 72 handheld records sit under IYN, eight under IYO, one under ITX (the 2020 Vscan Air decision) and one under SGJ, the code created when FDA granted the Pulsenmore ES De Novo request on October 31, 2025 for an ultrasound imaging system used at home by lay users. ¹⁹

The supplier base matters as much as the count. The 72 handheld records come from 29 distinct applicants: two of them first appear in 2010 to 2014, twelve in 2015 to 2019, ten in 2020 to 2024 and five in 2025 to mid-2026. Clarius has seven records, Chison, Leltek, EchoNous and Butterfly Network five each, and GE, FUJIFILM Sonosite and Healcerion four each; Philips has eight across three applicant name variants. ¹

US applicants hold 35 of the 72 handheld records and 66 of the 106 compact records. China is second in both classes with 13 and 30; the compact figure includes Mindray, SonoScape and GE's China entity. South Korea and Canada hold seven handheld records each and Taiwan six. Applicant country is the address on the submission, not where a device is built. ¹

For a fleet owner the message goes beyond any one brand. A young, multi-vendor base with entrants still arriving means a hospital will hold devices from companies with short service histories and terms that differ from each other. The durable basis for a fleet policy is therefore the written service term, not the vendor name: warranty length, battery term, stated service life and host-device requirement, captured per unit at purchase.

Reported problems point to software support and power-system checks

The FDA adverse event database records what users and manufacturers reported, not how often devices fail. Read with that limit, it still shows that the two classes report different things.

We took every MAUDE record received from January 2020 to July 2026 under IYN, IYO, ITX and SGJ: 7,750 records, of which 2,380 carry the transducer code ITX, 1,899 IYN and 3,471 IYO. Annual receipts rose from 686 in 2020 to 1,895 in 2024 and 1,688 in 2025. Brand and manufacturer text identifies 57 handheld records and 57 compact portable records; the remaining 7,636 are consoles, transducers and products that share the codes. The handheld set is Lumify 27, Youkey P50 Pocket Ultrasound 12, Sonosite iViz 4, Vscan Extend 4, Butterfly iQ and iQ+ 4, Clarius 2, EchoNous Uscan 2, Exo Iris 1 and Kosmos 1. The compact set is Philips CX50 28, GE Venue family 14, Vivid i, iq and q 7, Mindray M9 3, LOGIQ e 2 and Sonosite LX 1. Thirty-six of the 57 handheld records arrived in 2025, 22 of them on Lumify and 12 on the Youkey device, which shows how much one manufacturer's reporting shapes a small set. ²

Device-problem terms come from the openFDA event API, queried on September 12, 2026 for the same brand sets and for every IYN, IYO and ITX report in the window. A report can carry several terms, so the unit is a problem-term mention. The handheld brand set has 43 reports and 50 mentions; the compact set has 50 reports and 57 mentions; the all-system set has 5,472 reports and 6,643 mentions across the 100 most frequent terms; the all-transducer set has 2,504 reports and 2,842 mentions. ³

On the handheld set, software, app, operating-system and data terms are 31 of 50 mentions, or 62%. The most frequent single term is Application Program Freezes or Fails to Launch with 10 mentions, followed by No Device Output with 7, Incomplete or Inadequate Connection with 4 and No Display/Image with 3. Connection terms add a further 12%, bringing the combined software and connection category to 74% of coded mentions. Broad terms such as no output can have several underlying causes; these groupings guide triage rather than establish a root cause. Power and thermal terms are 14%: single mentions of Failure to Run on Battery, Overheating of Device, Thermal Decomposition of Device and Electrical Shorting. ³

On the compact set the picture inverts. Power, battery, charging and thermal terms are 23 of 57 mentions, or 40%: Fire 9, Failure to Power Up 2, Sparking 2, Electrical Overstress 2, Battery Problem 1 and single mentions of smoke, odour, intermittent loss of power and electrical shock. Physical and mechanical terms are 18% and software terms 23%. Across all system-code reports, by contrast, image quality is the largest theme at 25%, physical damage 22%, software 20% and power 9%. Across all transducer reports image quality is 41% and physical damage 34%. ³

The recall record points the same way, and recalls are counted actions with named causes rather than free-text reports.

• On March 6, 2025 GE Medical Systems initiated a correction covering 12,808 Venue Go and Venue Fit systems because a battery "can potentially develop an internal failure which could result in smoke or fire". Customers were told to switch off, remove the batteries and check their date of manufacture. A separate 2023 action concerned Venue Go carts whose tilt mechanism could fail and let the system detach. ¹⁰
• On November 4, 2021 GE initiated a correction covering 12,526 Vscan Extend units that failed to power on because of a depleted internal battery after the external battery was removed with the device still switched on, or after connection to a computer without AC power; a software update was the remedy. ¹¹
• On October 31, 2025 Philips initiated a correction covering 4,819 Lumify systems because compatibility issues with Apple devices running iOS 18 "may cause a failure to perform live imaging". The instructions were to use an Android device, not to update the iOS device, and to turn off automatic updates. ¹²
• On May 9, 2024 EchoNous initiated a correction covering 272 Kosmos systems on iOS because a software bug could make measurements performed in third-party software after DICOM export inaccurate; a patch followed. ¹³

All four selected power/software corrections illustrate dependencies that a service plan must cover. The two iOS-related examples concern platform compatibility or application/export software; this selected set is illustrative rather than a complete recall census. Overheating appears in the field literature as well: a ten-week evaluation of a handheld probe in a high-acuity emergency department listed "frequent overheating" and reliance on internet-based cloud storage among the device's disadvantages. ¹⁴

The boundaries of this evidence need stating once, plainly. MAUDE is passive reporting with duplicates, uneven narrative quality and no installed-base denominator, so none of the counts above is a rate and none says anything about who serviced a device. The event-type mix on the 57 handheld records (65% malfunction, 21% injury, 9% death) rests on 12 injury-coded and five death-coded reports; 32 of the 57 records state no clinical signs or symptoms and 12 state insufficient information. That mix is a coding artefact of a tiny set and is unusable as a safety comparison between classes. ²

The planning implication is to include app, host and connection support in handheld contracts and battery, adapter and power-chain checks in compact-system triage. These small, heterogeneous reporting cohorts support priorities for investigation, not exclusive failure profiles.

Read the warranty and the battery clause together

Warranty length is the number a buyer sees first. The manufacturer documents pair it with two other numbers that matter more for a five-year budget: the stated service life and the battery term.

GE HealthCare's Vscan Air support pages state that "the expected service life of the Vscan Air is 5 years" and instruct owners to "replace the probe battery every 5 years to maintain optimal safety and system functionality" with an authorised battery. A new battery gives 50 minutes of continuous scanning under the stated conditions and recharges from 10% to 90% in 75 minutes; the pages advise considering replacement when scan time falls well below that figure. The product page gives a three-year standard warranty. ⁵¹⁵¹⁶

Butterfly Network's iQ3 user manual (Revision E, October 2025) states that "the probe battery is not user-replaceable" and that replacement by anyone other than Butterfly Support "may result in a hazard such as higher temperatures, fire, or explosion"; that the probe "should be charged at least monthly"; and that the expected service life is five years for the probe and three years for the cable and charger. The specification page lists a 2220 mAh battery marked "Not replaceable", up to two hours of scanning, a 10% to 90% recharge in 90 minutes and a three-year warranty with an optional further two years. The app requires iOS 17.0 or newer or Android 12 or newer. ⁴¹⁷

Philips covers the Lumify transducer for five years and its accessories for one year, requires a device from its compatibility list and a Philips-approved cable, and needs internet access to register the transducer. The transducer has no battery of its own; it draws power through the host connection. ⁸ In July 2025 Philips issued a labeling correction across 171,322 transducer units, including the Lumify C5-2, L12-4 and S4-1, defining the expected useful life as five years for Lumify, transoesophageal and xMatrix transducers and seven years for endocavity and transcutaneous transducers, and asking customers who had exceeded it to run performance tests or contact Philips. ¹⁸

That correction has a regulatory context worth knowing. FDA's warning letter to Royal Philips dated September 9, 2025 records that Philips' own document had verified transducer useful life as three years, that seven refurbished transducers distributed past that life were associated with complaints, and that Philips then stopped distributing refurbished transducers beyond useful life, initiated a recall and updated its instructions for use. The letter concerns Philips' distribution controls and validated useful life. It supports checking model-specific life limits and refurbishment evidence; it establishes no universal five-year retirement rule for hospital ultrasound fleets. ¹⁹

For legacy Clarius HD scanners bought directly from Clarius from October 31, 2019, the cited terms give three years on new scanners, one year on refurbished scanners and six months on new batteries and accessories. The removable-battery example belongs to this series. The once-per-twelve-month battery remedy limit sits within optional Clarius Care, not the standard six-month warranty. HD3 purchases have separate terms, and distributor purchases follow the accompanying agreement. ⁶

FUJIFILM Sonosite's warranty schedule (Rev T) shows the compact class in its own terms: five years on newly manufactured SII, Edge II, ST, PX, ZX and LX systems and on their transducers, three years on iViz transducers, one year on the batteries for those systems, 90 days on spare parts, and extensions in one-year increments up to eight years from purchase. ⁷

Two budget distinctions follow. A five-year expected life provides a planning horizon; continued use depends on the exact instructions, condition, support and any applicable retirement requirement. The gap after a three-year standard warranty needs a reserve for paid manufacturer service or exchange, extended cover where available, or replacement. Separately, Sonosite lists a one-year battery warranty and extensions for eligible systems up to eight years. Warranty duration measures coverage, not battery lifespan or guaranteed system longevity. The table below is the checklist a buyer can ask any vendor to complete in writing.

What can still be repaired, and what has to be replaced

The same symptom takes different routes on the two classes. The matrix below sets them side by side with the evidence behind each row.

No power is the clearest case. On a sealed handheld the battery, the electronics and the transducer are one unit, so a cell that no longer holds charge is a warranty claim, a manufacturer battery service where the maker offers one (the Vscan Air schedule) or a replacement (the iQ3 battery is marked not replaceable). On a compact system a no-power call warrants qualified isolation of possible battery, adapter, power-board, coin-cell or cart-supply faults before a repair decision. Rongtao's portable power fault guide walks through that isolation sequence and the part-number traps that go with it. ²⁰

Fire, smoke or abnormal heat requires stopping use and following the manufacturer's safety and recall instructions for either class. On the compact class the 2025 Venue Go and Venue Fit action was a battery inspection and removal exercise across 12,808 systems, and the compact problem set carries nine Fire mentions; the subsequent service assessment must follow the applicable correction instructions. On a handheld, overheating is a documented operating limitation and any thermal event is a stop-use, report and warranty matter. ¹⁰³

Software-coded mentions form the largest category in the selected handheld reporting set. The Lumify iOS 18 correction and the Kosmos iOS patch were resolved by controlling the host: hold the update, use a listed device, install the patched app. A compact system's software lives on the system itself and is reloaded or repaired there. ¹²¹³

Cables and connectors are the one hardware item some handhelds let the owner replace. Butterfly's iQ3 manual documents a user-replaceable cable, and Philips requires its approved cable. On a compact system the probe cable, strain relief and connector are repair items. ⁴⁸

Cracked lenses, damaged housings and liquid ingress are, on a handheld, usually a replacement or an accidental-damage claim where the maker sells such cover. On a compact system the external probe is a repairable component, and Rongtao's probe repair-or-replace analysis sets out when lens, cable and housing repair is economic and when replacement wins. Physical damage is 34% of all transducer problem mentions in the 2020 to 2026 window, which is why that decision recurs. ²¹³

Poor image quality, the largest single theme on system reports at 25%, needs the same discipline on both classes: rule out gel, preset, software and host performance first. On a compact system the next steps are a probe swap test and then the front-end board; on a handheld there is no next step except the manufacturer. ³

The regulatory line between repairing and remanufacturing runs through this matrix. FDA's May 2024 guidance defines servicing as returning a device to the safety and performance specifications established by the manufacturer and its original intended use, and remanufacturing as any act that "significantly changes the finished device's performance or safety specifications, or intended use". The same guidance recommends that manufacturers' labeling for reusable devices include electrical characteristics "including batteries (e.g., chemistry, amperage, voltage, rechargeability)", the recommended maintenance schedule, troubleshooting steps and acceptance criteria. A like-for-like battery replacement intended to restore original specifications may be servicing; a change in specification requires assessment under the guidance. ²²

FDA's 2018 report on servicing supplies the policy backdrop. It concluded that the available objective evidence was "not sufficient to conclude whether or not there is a widespread public health concern related to servicing, including by third party servicers", that many manufacturers and third parties provide high-quality servicing, and that "the continued availability of third party entities to service and repair medical devices is critical to the functioning of the U.S. healthcare system". ²³

In Rongtao's assessment, sealed handheld hardware should follow the manufacturer's documented service route, while compact systems merit a component-level repair assessment where qualified testing and parts are available. The service provider must establish its ability to restore and verify the exact model's original specifications before accepting a repair.

Buyers are already tendering for portables

European public tenders show the class arriving in procurement language. We searched the EU Tenders Electronic Daily notices for the ultrasound and medical-equipment-servicing procurement codes and counted, from January 2024 to June 2026, notices whose titles contain an ultrasound term and a portable, handheld, pocket, wireless or point-of-care term in any EU language. ²⁴

Eleven of the 74 notices use a pocket, handheld, wireless-probe or POCUS term specifically; the rest say portable or mobile. Forty-three are contract notices, 30 are award notices and one is a prior information notice; all are supply contracts. ²⁴

Two limits apply. First, the series starts in 2024 because that is when notice titles began to carry the buyer's descriptive text: mean title length is 51 to 57 characters for 2016 to 2023 and 148 to 153 characters from 2024, so earlier titles carry no searchable form factor. Second, 53 of the 74 notices come from Polish buyers, with Romania at eight and no other country above three. The concentration is consistent with a national habit of writing device descriptions into titles as much as with purchasing volume, and the data offers no way to separate the two. ²⁴

The useful lesson is about tender language rather than market size. A notice that says "portable ultrasound" leaves open whether it wants a sealed handheld or a laptop system, and leaves unasked the terms that decide the five-year cost. In Rongtao's assessment a tender for either class should require, in writing, the expected service life of the device and of its battery, the battery warranty and whether the battery can be replaced without replacing the probe, the supported host devices and operating-system versions with a commitment on validation timing, and the loaner and turnaround terms for warranty repair.

Reprocessing and probe condition apply to both classes

Infection control and probe condition cut across the class split, and a fleet policy that stops at electronics misses them.

The AIUM guideline on cleaning and preparing transducers, reapproved on July 2, 2025, classifies external transducers that contact only clean, intact skin as non-critical devices to be cleaned after every use with low-level disinfection; transducers used on contaminated skin need a single-use cover, and transducers used for percutaneous procedures need cleaning and low-level disinfection with a single-use cover whose sterility follows the procedure. Internal transducers are semi-critical and need high-level disinfection. Those rules apply to a handheld probe exactly as they apply to a probe on a cart, with one practical difference: on integrated handhelds, the electronics and sometimes a battery sit inside the housing being disinfected, so the manufacturer's compatible-agent list is the limit. Butterfly's specification page, for example, lists high-level disinfection with Cidex OPA and low-level disinfection with approved wipes for the iQ3. ²⁵¹⁷

Probe condition is a fleet-wide issue rather than a handheld one. A 2016 multicentre survey inspected 219 probes at 12 UK sites using visual inspection and the in-air reverberation pattern: 63% showed no fault, 25% had a fault needing further action and 13% should have been removed from use, and the authors note that simple tests of this kind can reveal over 90% of probe faults. A 2014 hospital-wide survey cultured 82 point-of-care probes four times each over eight weeks; 18 of 320 cultures, or 5.6%, grew organisms, all non-pathogenic skin or environmental flora, and no gel bottle grew anything. ²⁶²⁷

For fleet planning these two studies justify a periodic visual and image check on every probe of either class, and a decision rule for damaged housings. Rongtao's high-level disinfection report covers the point at which housing or lens damage stops a probe being reprocessed safely, which on a compact system leads to a repair quote and on a handheld leads back to the manufacturer. ²⁸

A three to five year budget template for a two-class fleet

The budget follows the documents. The template below carries no prices; it lists the inputs each class needs and the years in which the manufacturer terms quoted above fall due. Filling it requires each unit's purchase date, serial-specific warranty terms and the current price list from the vendor or the service provider.

Year one establishes purchase records and host-update controls: enrol every host phone or tablet in the hospital's device-management system with automatic operating-system updates held until the vendor confirms compatibility, and record each unit's warranty end, stated life and battery term in the asset register.

Years two and three are the warranty years for most handhelds and the years in which compact batteries pass their one-year term. The handheld budget line is cables, host-device replacement and any paid extended cover; the compact line is batteries, adapters and the first repair quotes on probes.

Year three is the end of the standard warranty on the Vscan Air, iQ3 and Clarius. From this point the budget should cover applicable extended warranty, paid manufacturer service or exchange, and replacement if repair is unavailable. Obtain the actual battery-coverage exclusions before selecting extended cover.

Year five is the stated service life on the handhelds that state one and the end of the standard warranty on the Sonosite systems. The handheld reserve is reviewed against the model's life instructions, condition and available support; the compact decision compares eligible extended cover, qualified independent repair with spares, and replacement.

The Monday-morning version fits on one page. Tag every unit as handheld or compact. Pull each unit's warranty end date, stated service life and battery term. Freeze mobile operating-system updates on app-tethered devices until compatibility is confirmed. Build the compact spare pool: battery, adapter, dock or power board, compatible probes sized to service demand. Fund a replacement reserve against the stated life and record the model-specific decision for continued use.

Where an independent repair partner fits

Rongtao Medical is an independent ultrasound parts and repair company founded in 2013 in Guangzhou, serving service partners, distributors and hospital engineering teams in more than 140 countries and regions. Its 3,000 square metre technical and warehousing centre holds more than 3,000 parts SKUs and hundreds of complete systems and probes, staffed by more than 35 senior engineers, and its quality system is certified to ISO 13485:2016 and ISO 9001:2015. ²⁹

The company's work sits on the compact and cart side of the line drawn in this report: core board repair, probe solutions and tested replacement parts, with Mindray M7 and M9 portables among the platforms its published coverage lists. Every part or repaired board goes through a 48-hour real-machine test before shipment, with photos or video where applicable; standard turnaround is five to eight business days; shipping is by DHL, FedEx or UPS from a bonded zone with customs paperwork; and the typical warranty is 90 days, with extended options on request. Its published coverage stops short of sealed handheld probes, which stay on the manufacturer route described above. Manufacturer names identify platforms only and imply no affiliation or authorisation. ²⁹

For a fleet owner the practical use is on the compact side of the template: a repair quote for a power board, a probe or a complete system before the unit is written off, and a tested spare for the pool.

Methodology and boundaries

Clearance analysis used the FDA 510(k) database export dated July 22, 2026 (175,559 records, decisions through June 29, 2026), restricted to product codes IYN, IYO, ITX and SGJ, classified by a documented keyword and model-name rule applied to device name and applicant, with every handheld and compact record reviewed by eye. Records are premarket decisions, not sales or installed base, and the compact class is a lower bound. ¹

Adverse event analysis used MAUDE records received from January 2020 to July 2026 under the same codes, classified by brand and manufacturer text, and device-problem term counts from the openFDA event API on September 12, 2026, grouped into service themes using the IMDRF device-problem hierarchy. Counts are patterns from passive reporting, not rates, and say nothing about servicer causation. Recall records were read from the FDA Medical Device Recalls database for the five event numbers cited. ²³

Tender analysis used EU TED notices for the ultrasound and equipment-servicing procurement codes from 2024 to June 2026, with a multilingual title rule and unique publication numbers; the pre-2024 title format prevents a longer series and one country dominates the matches. ²⁴

Two lanes were tried and set aside. UN Comtrade import data for the ultrasound apparatus heading was pulled for twelve reporters from 2014 to 2024 to test whether import value per unit had fallen as portables spread; only 53 of 132 reporter-years carried a usable quantity and the quantities were not comparable between reporters, so no unit value is reported. UK MHRA alert lists to June 2026 contained three ultrasound alerts, all about decontamination or covers, and their weekly field-safety-notice lists do not name devices, so no handheld or battery notice could be identified. ³⁰

Manufacturer terms are quoted from documents read on September 12, 2026 and describe stated warranty and life, not measured field life; they change without notice. No peer-reviewed field study of handheld device failure or replacement rates was found in the literature searched, and this report offers none.

Frequently asked questions

Does a five-year warranty or a five-year stated service life mean a handheld will last five years? No. A stated service life is the manufacturer's design horizon and a warranty is a repair obligation; neither is a performance guarantee. On a sealed handheld the practical limits are the battery term and the host-device requirement, both of which can end usable life inside the warranty window or after it. The Butterfly iQ3 states a five-year probe life with a battery that is not replaceable and a three-year standard warranty, so the two years between them are the period a budget must cover. ⁴¹⁷

Can a hospital replace the battery in a handheld probe? It depends on the model and the document. Butterfly marks the iQ3 battery as not user-replaceable and states that replacement by anyone other than its support organisation may create a heat, fire or explosion hazard. GE states a five-year battery replacement schedule for the Vscan Air with an authorised battery. The legacy Clarius HD example has a removable battery, six-month standard coverage and an annual battery remedy limit under optional Clarius Care; check separate HD3 and distributor terms. Ask the vendor for the battery clause in writing before purchase. ⁴⁵⁶

What happens when the phone or tablet updates? Two selected iOS-related corrections illustrate the issue: an iOS 18 compatibility problem that could stop live imaging on 4,819 Lumify systems and an iOS software bug affecting exported measurements on 272 Kosmos systems. Holding operating-system updates on clinical host devices until the app vendor confirms compatibility is the control that follows. ¹²¹³

Is an out-of-warranty compact portable worth repairing? Usually the question is answerable part by part. The compact problem set is dominated by power and battery terms, the manufacturer schedules list batteries and spare parts as separate covered items, and the components behind a no-power fault can be tested individually. A repair quote for the failed part, compared with the replacement cost and the remaining probe life, decides it; the calendar decides nothing. ³⁷²⁰