Finished Disposable Medical Electrode Batch Sampling Inspection Standard & Full Test Items

Published: JULY 27, 2026 - Shanghai Zhichen Medical Technology Co., Ltd.

Batch finished electrode inspection is the last quality control link before factory delivery, which directly determines whether the batch can be exported to hospitals and overseas distributors. This article unifies sampling plan, visual inspection, electrical performance, gel physical property and packaging sealing test items, as well as unqualified batch judgment rules in line with ISO13485 system requirements.

1 Batch Division & Sampling Quantity Standard

1.1 Batch Division Rule

Products produced in one continuous production shift, same raw material batch, same EO sterilization cycle are defined as one independent inspection batch, batch number marked uniformly on outer carton.

1.2 AQL Sampling Level

Adopt General Inspection Level II; Critical defect AQL=0.4; Major defect AQL=1.0; Minor defect AQL=4.0.

1.3 Sampling Quantity Reference

Batch ≤5,000 pcs: take 125 samples

5,000~20,000 pcs: take 200 samples

>20,000 pcs: take 315 samples

2 Full Visual Appearance Inspection Items

Substrate surface: no scratches, holes, fiber shedding

Conductive snap: no rust, offset, loose riveting

Hydrogel: uniform thickness, no shortage, no bubble, no overflow

Release liner: complete, no damage, easy peeling without residual glue

Outer packaging: intact sealing, clear batch/expiry printing

3 Electrical Performance Key Tests

3.1 ECG Electrode Impedance Test

Test at 10Hz signal, impedance value ≤2000Ω, excessive impedance causes ECG waveform drift.

3.2 TENS Carbon Film Surface Resistance

Range 150~600Ω/sq, adjustable according to customer equipment requirements.

3.3 Neutral Plate High-Frequency Conductivity

Uniform current dispersion test, no local high resistance hot spot under electrosurgical power.

4 Hydrogel Physical Index Inspection

4.1 Viscosity & Tack Test

Meet repeated adhesion standard for TENS pads; single-use ECG gel moderate tack without residual glue.

4.2 Water Locking & Dehydration Resistance

Simulate 30-day warehouse storage environment, test impedance change rate after moisture loss.

4.3 Skin Irritation Spot Check

Monthly random batch send to third-party lab for ISO10993 irritation test.

5 Packaging & Sterility Inspection

5.1 Sealing Integrity Test

Immersion leak detection, no air bubble overflow under negative pressure to ensure EO sterilization barrier.

5.2 Sterile Validity Confirmation

Randomly take biological indicator card from sterilization batch to verify complete microbial inactivation.

5.3 Outer Carton Label Audit

Check model, batch, production date, expiry date, CE/FDA marking complete and error-free.

6 Defect Classification & Batch Reject Rules

6.1 Critical Defects (Batch Direct Reject)

Impedance exceeds limit, packaging leak, snap falling off, gel severe dehydration, biological indicator unqualified.

6.2 Major Defects

Gel shortage, obvious substrate scratches, blurred batch printing; if unqualified quantity reaches reject number, the whole batch is blocked for rework screening.

6.3 Minor Defects

Tiny printing offset, slight liner wrinkles, within allowable quantity can pass delivery.

7 Inspection Record Archiving Requirements

Each batch inspection report shall record batch number, sampling quantity, each test item data, inspector signature, inspection date, stored together with sterilization records for ISO13485 audit.

Summary

Standardized batch sampling inspection can effectively intercept defective products before delivery, avoid overseas customer returns and certification risks, and is a necessary quality control link for long-term stable export of medical electrode factories.