(126 days)
The Mini Patch, model: WL-2301A & WL-2301B Transcutaneous Electrical Nerve Stimulators are intended for temporary relief of pain associated with sore and aching muscles in the upper and lower extremities (arm and/or leg) due to strain from exercise or normal household and work activities.
The Mini Patch, models WL-2301B are transcutaneous electrical nerve stimulator used for pain relief by applying an electrical current to electrodes, which are attached on the skin. The output and waveform characteristic is fixed for every model, only the intensity is adjustable.
The Mini Patch, models WL-2301A & WL-2301AB, consist mainly of two parts: the stimulus generator, electrode. The stimulus generator generates the output current specified as the input of controller. The output port transmits the output current to the electrode, which is attached to the patient's skin so as to transmit this stimulus current to the patient for pain relief.
The stimulation mode for Mini Patch is burst mode with fixed pulse rate, frequency, and fixed timer, only amplitude is adjustable. This operation way is considered the simplification from the burst mode of comparison clear model, WL-2302(K020020). Every model of Mini-TENS has its individual stimulation operation cycle.
This 510(k) summary describes a Transcutaneous Electrical Nerve Stimulator (TENS) device, the "Mini Patch" (models WL-2301A & WL-2301B), intended for temporary pain relief. The submission focuses on demonstrating substantial equivalence to a predicate device, not on proving clinical efficacy through a new clinical effectiveness study. Therefore, many of the requested criteria (like ground truth, expert adjudication, MRMC studies, standalone performance, and training set information) are not applicable as this type of submission typically relies on engineering and performance testing to show the new device operates similarly and safely to an already cleared device.
Here's a breakdown based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
For this type of device and submission (510(k) for substantial equivalence), the "acceptance criteria" are primarily established through compliance with recognized standards and comparison to a predicate device's specifications. The study demonstrating this is a non-clinical comparison and verification/validation testing.
| Acceptance Criteria (Comparison to Predicate Device WL-2407 (K091757)) | Reported Device Performance (Mini Patch WL-2301A & WL-2301B) |
|---|---|
| Intended Use: Same as predicate | Same (temporary relief of pain in upper/lower extremities due to sore muscles) |
| Product Code: Same as predicate (NUH) | Same |
| Regulation Number: Same as predicate (21 CFR 882.5890) | Same |
| Prescription or OTC: Same as predicate (OTC) | Same |
| Manufacturer: Same as predicate (Well-Life) | Same |
| Power Source(s): Similar (Predicate: 1.5Vx3 AAA; New: 3Vx1) | 3Vx1 |
| Method of Line Current Isolation: Same as predicate (Type BF) | Same |
| Patient Leakage Current (Normal): Under 0.1 uA | Same (Under 0.1 uA) |
| Patient Leakage Current (Single Fault): Under 0.5 uA | Same (Under 0.5 uA) |
| Number of Output Modes: Similar (Predicate: 8; New: 3) | 3 |
| Waveform: Same as predicate (Biphasic, Rectangular) | Same |
| Max Output Voltage (@500Ω): Predicate: 40V; New: 30V | 30V |
| Max Output Current (@500Ω): Predicate: 80mA; New: 60mA | 60mA |
| Duration of Primary Phase: Predicate: 260 Max usec; New: 250 Max usec | 250 Max usec |
| Pulse Duration: Predicate: 500.26 ms/Max.; New: 33.58 ms/Max. | 33.58 ms/Max. |
| Frequency (Rate): Same as predicate (60 Max Hz) | Same (60 Max Hz) |
| Symmetrical phases? Same as predicate (No) | Same (No) |
| Net charge: Zero for symmetrical biphasic wave | Achieved (Zero for symmetrical biphasic wave) |
| Max. phase charge: Predicate: 20.8 uc; New: 15 uc | 15 uc |
| Max. current Density: Predicate: 0.050 mA/cm²; New: 0.055 mA/cm² | 0.055 mA/cm² |
| Max. Average Current (RMSA) (@500Ω): Predicate: 38.43mA; New: 29.394mA | 29.394 mA |
| Max. Power Density: Predicate: 0.0020Watts/cm²; New: 0.0017Watts/cm² | 0.0017Watts/cm² |
| Compliance with Voluntary Standards: ANSI/AAMI NS4, IEC 60601-1, IEC 60601-1-2 | Same |
| Compliance with 21 CFR 898: Yes | Same |
| Software Verification: Carried out according to FDA guidance | Confirmed as carried out |
The "study" that proves the device meets the acceptance criteria is the non-clinical testing, verification, and validation activities performed by the manufacturer, as summarized in sections 6, 8, and 9 of the 510(k) submission. These tests compare the new device's technical specifications and safety features against those of the predicate device and relevant voluntary standards to demonstrate that the small differences do not raise new questions of safety or effectiveness.
2. Sample size used for the test set and the data provenance
- Sample Size for Test Set: Not applicable in the context of a clinical test set. The submission refers to engineering and performance verification and validation tests for the device itself, not patient data. These tests would involve multiple units of the new device to confirm consistency and adherence to specifications.
- Data Provenance: Not applicable for clinical data. The data provenance is from the manufacturer's internal engineering and testing labs in Taiwan, ROC, where the device was developed and tested. This is a retrospective comparison to an existing predicate device's specifications and prospective engineering testing of the new device's physical and electrical properties.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Not applicable. This submission is for substantial equivalence of a TENS device based on engineering and performance testing, not a diagnostic or clinical study requiring expert-established ground truth from patient data. The "ground truth" here is the adherence to electrical engineering specifications and safety standards as outlined by regulatory bodies and voluntary standards.
4. Adjudication method for the test set
- Not applicable. No expert adjudication of clinical cases was performed, as this was not a clinical study involving interpretation of patient data.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
- Not applicable. This device is a TENS unit, not an AI-powered diagnostic or assistive tool for human readers. No MRMC study was conducted.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Not applicable. This is a physical medical device (TENS unit), not an algorithm. Its "standalone" performance refers to its operational characteristics (output voltage, current, etc.) which were assessed through engineering tests as described in the comparison tables.
7. The type of ground truth used
- Engineering Specifications and Safety Standards (e.g., ANSI/AAMI, IEC 60601-1, IEC 60601-1-2): The "ground truth" for this submission is adherence to established electrical and mechanical safety standards and conformity to the operational parameters of a legally marketed predicate device (Well-Life OTC TENS, K091757), which itself was cleared based on similar principles.
8. The sample size for the training set
- Not applicable. This device does not use machine learning or AI, so there is no training set in the conventional sense.
9. How the ground truth for the training set was established
- Not applicable. As there is no training set, this is irrelevant.
§ 882.5890 Transcutaneous electrical nerve stimulator for pain relief.
(a)
Identification. A transcutaneous electrical nerve stimulator for pain relief is a device used to apply an electrical current to electrodes on a patient's skin to treat pain.(b)
Classification. Class II (performance standards).