(483 days)
The device is intended for medical purposes to provide mobility to persons restricted to a sitting position.
The Wu's Electrical Scooter, WT-M4JKx, is an indoor-use electrical scooter that is battery operated. It has a base with 4 wheels, a seat and 2 armrests. The movement of the electrical scooter is controlled by the rider who uses speed control lever to control the direction and speed of an electrical scooter. The motor power is 470W. The device uses a PG S-Drive 70A electronic controller. The device is provided with an off-board battery charger (Input: AC100-240V, Output: DC 24V, 5 Amp). The maximum weight capacity of WT-M4JKx is 400 lbs (182 kg), and its maximum forward speed is 5.9 mph (9.5 km/h).
The provided text describes the regulatory clearance for a medical device called "Wu's Electrical Scooter, WT-M4JKx". The document focuses on demonstrating substantial equivalence to a predicate device (Wu's Electrical Scooter, WT-M4Jr, K032489) through compliance with recognized standards and comparison of specifications.
Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implicitly defined by the safety and performance standards the device was tested against (primarily RESNA WC-1 and ISO 7176 series), and the comparison to the predicate device's performance. The reported device performance is the outcome of these tests.
| Acceptance Criterion (Standard / Feature) | Reported Device Performance (Subject Device: WT-M4JKx) |
|---|---|
| Safety Standards | |
| RESNA WC-1:2009 Wheelchairs - Volume 1 (General) | Compliant |
| RESNA WC-2:2009 Wheelchairs - Volume 2 (Electrical Systems) | Compliant |
| RESNA WC-2:2009 Section 21 (EMC) | Compliant |
| ISO 7176-16:2012 (Resistance to ignition of postural support) | Compliant |
| ISO 7176-25: 2013 (Batteries and Chargers) | Compliant |
| ISO 7176-15:1996 (Dimensions and Mass) | Compliant |
| Biocompatibility | |
| Cytotoxicity (various parts) | Passed |
| Sensitization (various parts) | Passed |
| Skin Irritation tests (various parts) | Passed |
| Delayed-type hypersensitivity (Epicutan test) (various parts) | Passed |
| Performance (RESNA WC-1 Section 1:2009 - Static Stability) | |
| Static stability downhill (Max.) | 26° |
| Static stability downhill (Min.) | 16° |
| Static stability uphill (Max.) | 16° |
| Static stability uphill (Min.) | 15° |
| Static stability sideways (Max.) | 9.5° |
| Performance (RESNA WC-1 Section 2:2009 - Dynamic Stability) | |
| Dynamic stability downhill | 6° |
| Performance (RESNA WC-1 Section 3:2009 - Braking) | |
| Minimum braking distance from max speed | 1.4m |
| Performance (RESNA WC-1 Section 4:2009 - Cruising Range) | |
| Cruising range | 29km |
| Performance (RESNA WC-1 Section 5:2009 - Dimensions & Turn) | |
| Overall length | 1210mm |
| Overall width | 580mm |
| Total mass | 85.5kg |
| Minimum turning radius | 1400mm |
| Minimum turn-around width | 1600mm |
| Performance (RESNA WC-1 Section 6:2009 - Speed) | |
| Maximum speed forward | 9.5km (5.9 mph) |
| Performance (RESNA WC-1 Section 7:2009 - Seat Dimensions) | |
| Seat plane angle (Max.) | 5° |
| Effective seat depth | 430mm |
| Effective seat width | 460mm |
| Seat surface height at front edge (Min.) | 570mm |
| Backrest angle | 10° |
| Backrest height | 360mm |
| Performance (RESNA WC-1 Section 10:2009 - Obstacle Climbing) | |
| Obstacle climbing (Max.) | 50mm |
| Obstacle climbing (Min.) | 15mm |
| Performance (ISO 7176-15:1996 - Footrest & Armrest) | |
| Footrest to seat distance (Max.) | 475mm |
| Footrest to seat distance (Min.) | 425mm |
| Leg to seat surface angle | 90° |
| Armrest to seat distance | 210mm |
| Front location of armrest structure | 320mm |
| Other Specifications | |
| Maximum weight capacity | 400 lbs (182 kg) |
| Curb climbing ability | 1.96"/50mm |
| Operating environments | Indoor use |
2. Sample Size Used for the Test Set and Data Provenance
The document does not specify a "test set" in the context of a typical clinical study with human subjects. Instead, the device's performance is demonstrated through bench testing against recognized industry standards (RESNA, ISO) and biocompatibility testing of its components.
- Sample Size: The sample size for these engineering and materials tests is not explicitly stated, but it is typically one or a small number of physical units of the device and its components, sufficient to perform the required measurements and evaluations per the standards.
- Data Provenance: The tests were conducted according to international and national standards. The country of origin of the data is not directly mentioned beyond the manufacturer being in Taiwan. The nature of these tests is prospective in the sense that the new device was built and then rigorously tested to meet pre-defined engineering and safety benchmarks. There is no indication of retrospective data.
3. Number of Experts Used to Establish Ground Truth and Their Qualifications
This information is typically relevant for studies involving subjective human assessment (e.g., image interpretation). For this device, the "ground truth" is established by the objective measurements and adherence to the specified engineering and safety standards.
- Number of Experts: Not applicable in the sense of establishing a subjective "ground truth." The experts involved would be the test engineers and laboratory personnel from the accredited testing facilities that performed the RESNA and ISO standard tests.
- Qualifications of Experts: Not specified, but implied to be qualified and accredited by virtue of conducting tests according to international standards.
4. Adjudication Method for the Test Set
Not applicable. Adjudication methods (like 2+1, 3+1) are for resolving discrepancies in human expert opinions, which is not relevant for objective engineering and biocompatibility testing. The "adjudication" here is the pass/fail result against the criteria set by the standards.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No. An MRMC comparative effectiveness study is designed to evaluate differences in diagnostic accuracy or effectiveness among human readers, often with and without AI assistance, using a set of cases. This type of study is not relevant for a motorized scooter.
- Effect Size: Not applicable.
6. Standalone Performance (Algorithm Only without Human-in-the-Loop Performance)
Yes, in the sense that the device itself (the "algorithm only") was tested against established performance and safety standards, independent of direct interaction with a human in a clinical efficacy setting. The performance metrics listed above (e.g., dynamic stability, braking distance, cruising range, maximum speed) are intrinsic to the device's design and function and were measured directly from the physical product. There is no "human-in-the-loop performance" analysis detailed for this device in the context of its regulatory clearance.
7. Type of Ground Truth Used
The ground truth used for this device is based on:
- Established engineering and safety standards: RESNA WC-1, RESNA WC-2, ISO 7176 series. The performance of the device is measured against the requirements and test methods defined by these standards.
- Objective material properties and biological response: For biocompatibility, the ground truth is established by the results of cytotoxicity, sensitization, skin irritation, and delayed-type hypersensitivity tests performed according to ISO 10993 standards.
- Comparative equivalence to a predicate device: The regulatory submission establishes that the subject device's performance is "as safe, as effective, and performs as well as" a legally marketed predicate device (K032489 Wu's Tech WT-M4Jr). This comparison itself forms a type of ground truth for regulatory purposes.
8. Sample Size for the Training Set
Not applicable. "Training set" refers to data used to train machine learning models. This device is a physical medical device (electrical scooter), not an AI/ML-driven software product.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no training set for this type of device.
§ 890.3800 Motorized three-wheeled vehicle.
(a)
Identification. A motorized three-wheeled vehicle is a gasoline-fueled or battery-powered device intended for medical purposes that is used for outside transportation by disabled persons.(b)
Classification. Class II (performance standards).