Test Traceability for Medical Devices

FDA 21 CFR Part 820 requires medical device manufacturers to maintain a Device History Record (DHR) for every unit produced. TofuPilot captures test results, serial numbers, measurements, and pass/fail determinations in an immutable record that maps directly to FDA and ISO 13485 requirements.

Regulatory Requirements Overview

Medical device test traceability sits at the intersection of two frameworks. Both require documented evidence that each device was manufactured and tested according to approved procedures.

Regulation	Clause	Requirement	TofuPilot Feature
21 CFR 820.184	DHR	Records demonstrating device manufactured per DMR	Test records per serial number with procedure name
21 CFR 820.80	Receiving, in-process, finished device acceptance	Acceptance activities with acceptance/rejection documented	Pass/fail results with measurement limits
21 CFR 820.90	Nonconforming product	Documented investigation of nonconformances	Failed runs with measurement-level detail
21 CFR 820.180	General requirements (records)	Records maintained for device lifetime or 2 years	Immutable cloud storage with retention
21 CFR 820.250	Statistical techniques	Valid statistical techniques for process capability	Cpk, control charts, FPY in dashboard
ISO 13485 7.5.3	Traceability	Records per unit or batch through production	Serial tracking, unit history, sub-assembly links
ISO 13485 8.2.4	Monitoring and measurement	Evidence of conformity to acceptance criteria	Measurements with units, limits, and pass/fail

Structuring Tests for DHR Compliance

The DHR must include test results that prove each device was manufactured according to its Device Master Record (DMR). Structure your OpenHTF tests so each procedure maps to a documented test protocol.

test_medical_device.py

# Medical device production test aligned with DHR requirements
import openhtf as htf
from openhtf.util import units
from tofupilot.openhtf import TofuPilot

@htf.measures(
    htf.Measurement("impedance_channel_1")
        .in_range(minimum=980, maximum=1020)
        .with_units(units.OHM)
        .doc("Electrode impedance per IEC 60601-1, channel 1"),
    htf.Measurement("impedance_channel_2")
        .in_range(minimum=980, maximum=1020)
        .with_units(units.OHM)
        .doc("Electrode impedance per IEC 60601-1, channel 2"),
    htf.Measurement("leakage_current")
        .in_range(maximum=0.00001)
        .with_units(units.AMPERE)
        .doc("Patient leakage current, Type BF applied part per IEC 60601-1"),
)
def electrical_safety(test):
    test.measurements.impedance_channel_1 = 1002.3
    test.measurements.impedance_channel_2 = 997.1
    test.measurements.leakage_current = 0.000003

@htf.measures(
    htf.Measurement("signal_accuracy_pct")
        .in_range(minimum=99.0, maximum=101.0)
        .doc("Measurement accuracy against NIST-traceable reference"),
    htf.Measurement("noise_floor")
        .in_range(maximum=0.000005)
        .with_units(units.VOLT)
        .doc("Input-referred noise, 0.05-150 Hz bandwidth"),
    htf.Measurement("common_mode_rejection")
        .in_range(minimum=100)
        .doc("CMRR at 50/60 Hz, in dB"),
)
def signal_performance(test):
    test.measurements.signal_accuracy_pct = 99.8
    test.measurements.noise_floor = 0.0000021
    test.measurements.common_mode_rejection = 112.4

@htf.measures(
    htf.Measurement("firmware_version")
        .doc("Installed firmware version, must match DMR revision"),
    htf.Measurement("self_test_result")
        .in_range(minimum=1, maximum=1)
        .doc("Device self-test pass (1) or fail (0)"),
    htf.Measurement("battery_capacity_pct")
        .in_range(minimum=95)
        .doc("Battery capacity relative to rated"),
)
def system_validation(test):
    test.measurements.firmware_version = "3.2.1-release"
    test.measurements.self_test_result = 1
    test.measurements.battery_capacity_pct = 98.7

def main():
    test = htf.Test(
        electrical_safety,
        signal_performance,
        system_validation,
    )
    with TofuPilot(test):
        test.execute(test_start=lambda: "MD-2026-04-00192")

if __name__ == "__main__":
    main()

Each measurement references the applicable standard and includes acceptance limits. TofuPilot stores the procedure name, the serial number (UDI-linked), and every measurement with its result.

Acceptance Activities (21 CFR 820.80)

The FDA requires documented acceptance activities at receiving, in-process, and finished device stages. Run separate OpenHTF procedures for each stage, all using the same serial number.

test_acceptance_stages.py

# Three-stage acceptance testing for FDA 820.80 compliance
import openhtf as htf
from openhtf.util import units
from tofupilot.openhtf import TofuPilot

@htf.measures(
    htf.Measurement("incoming_visual_pass")
        .in_range(minimum=1, maximum=1),
    htf.Measurement("incoming_dimension_check")
        .in_range(minimum=24.9, maximum=25.1)
        .with_units(units.MILLIMETRE),
)
def receiving_inspection(test):
    test.measurements.incoming_visual_pass = 1
    test.measurements.incoming_dimension_check = 25.02

@htf.measures(
    htf.Measurement("solder_paste_height")
        .in_range(minimum=0.10, maximum=0.15)
        .with_units(units.MILLIMETRE),
    htf.Measurement("component_presence")
        .in_range(minimum=1, maximum=1),
)
def in_process_inspection(test):
    test.measurements.solder_paste_height = 0.12
    test.measurements.component_presence = 1

@htf.measures(
    htf.Measurement("final_functional_test")
        .in_range(minimum=1, maximum=1),
    htf.Measurement("label_verification")
        .in_range(minimum=1, maximum=1),
)
def finished_device_acceptance(test):
    test.measurements.final_functional_test = 1
    test.measurements.label_verification = 1

def run_stage(phase, serial):
    test = htf.Test(phase)
    with TofuPilot(test):
        test.execute(test_start=lambda: serial)

def main():
    serial = "MD-2026-04-00192"
    run_stage(receiving_inspection, serial)
    run_stage(in_process_inspection, serial)
    run_stage(finished_device_acceptance, serial)

if __name__ == "__main__":
    main()

TofuPilot's unit page for this serial shows all three acceptance stages in order. An FDA inspector can see the complete manufacturing and test history from a single page.

Nonconforming Product (21 CFR 820.90)

When a device fails testing, the FDA requires documented investigation. TofuPilot records the exact measurement that triggered the failure, its value, and the limit it exceeded.

Failed test runs are immediately visible in TofuPilot's dashboard. The unit's history page shows every attempt, so you can track the investigation, rework, and retest cycle. This satisfies the 820.90 requirement to document the nonconformance, investigation, and disposition.

Component Traceability with Sub-Units

ISO 13485 clause 7.5.3 requires traceability of components used in each device. Use TofuPilot's sub_units feature to link component serial numbers to the finished device.

test_component_traceability.py

# Record component serials for ISO 13485 traceability
import openhtf as htf
from tofupilot.openhtf import TofuPilot

@htf.measures(
    htf.Measurement("assembly_complete")
        .in_range(minimum=1, maximum=1),
)
def final_assembly(test):
    test.measurements.assembly_complete = 1

def main():
    test = htf.Test(final_assembly)
    with TofuPilot(
        test,
        sub_units=[
            {"serial_number": "SENSOR-2026-08812"},
            {"serial_number": "PCBA-2026-04410"},
            {"serial_number": "BATT-2026-11023"},
        ],
    ):
        test.execute(test_start=lambda: "MD-2026-04-00192")

if __name__ == "__main__":
    main()

If a component supplier issues a recall, you can trace which finished devices contain affected components through TofuPilot's unit hierarchy.

Audit Trail and Exports

TofuPilot provides the documentation that FDA and ISO 13485 auditors expect:

Device History Record. Every test run for a serial number, with procedure, station, operator, measurements, and result. This forms the test portion of the DHR.
Process capability. Cpk values and control charts for any measurement, demonstrating statistical process control per 21 CFR 820.250.
Failure analysis. Failure Pareto and measurement histograms to support CAPA investigations.
Record retention. Immutable storage with no ability to alter or delete historical records through the standard interface.

Export test data from the dashboard for inclusion in your formal DHR documentation package. Records include timestamps, station identifiers, and all measurement values with their acceptance criteria.