As a TENS device, the Focus is indicated for the following conditions: - symptomatic relief and management of chronic, intractable pain - adjunctive treatment for post-surgical and post-trauma acute pain As a NMS/NMES device, the Focus is indicated for the following conditions: - relaxation of muscle spasm - prevention or retardation of disuse atrophy - increasing local blood circulation - muscle re-education - prevention of venous thrombosis of the calf muscles immediately after surgery - maintaining or increasing range of motion As a FES device, the Focus is indicated for the following condition: - stimulation of the muscles in the leg and ankle of partially paralyzed patients to provide flexion of the foot and thus improve the patient’s gait
Device Story
Empi Focus is a dual-channel NMES/TENS/FES unit; delivers Empi Bi-Sourced® electrical stimulation via leadwires and electrodes. Device features 8 pre-programmed regimens; 2 output levels (0-40mA or 0-60mA); powered by 9V battery. Operated by clinician or patient; used for pain management, muscle rehabilitation, and gait training. Includes safety interlock preventing current delivery from 'no output' state. Output parameters (pulse width, frequency, ramp time) controlled by masked microprocessor. Healthcare providers use device to manage pain or facilitate physical therapy; output affects muscle contraction or sensory nerve stimulation to achieve therapeutic goals.
Clinical Evidence
Bench testing only. Functional testing performed against product specifications demonstrated compliance with requirements. No clinical data required for equivalence.
Indicated for patients requiring symptomatic relief of chronic intractable pain, post-surgical/post-trauma acute pain, muscle spasm relaxation, prevention/retardation of disuse atrophy, increased local blood circulation, muscle re-education, prevention of post-surgical venous thrombosis, maintenance/increase of range of motion, and gait improvement in partially paralyzed patients via leg/ankle muscle stimulation.
Regulatory Classification
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.
Predicate Devices
Empi Focus Model 727
Empi Respond Select
Submission Summary (Full Text)
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K951951
# 510(K) SUMMARY OF SAFETY AND EFFECTIVENESS
May 17 1995
The assigned 510(k) number is: K951951
This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.
| Applicant name: | Empi, Inc. |
| --- | --- |
| Applicant address: | 5255 East River Rd.
Fridley, MN 55421 |
| Contact person: | Stacy Mattson, Regulatory Affairs Manager |
| Phone: | 612-586-7354 |
| Date Prepared: | August 21, 1995 |
| Classification Name: | Transcutaneous Electrical Nerve Stimulator (TENS)
Powered Muscle Stimulator (NMES)
External Functional Neuromuscular Stimulator (FES) |
| Common/Usual Name: | NMES/TENS/FES unit |
| Trade/Proprietary Name: | Empi Focus |
| Equivalent Devices: | Empi Focus Model 727
Empi Respond Select |
## Product Description:
The Focus Unit is a dual channel NMES/TENS device with four conventional modes of operation, eight pre-programmed regimens and a choice of two levels of output (0-40mA or 0-60mA). It is powered by a standard 9V alkaline or NiCad rechargeable battery. All operation modes produce the Empi Bi-Sourced® waveform.
The Focus Unit requires the use of a set of leadwires and one or two pair of electrodes. All NMES/TENS electrodes currently distributed by Empi are appropriate for use with the Focus. The use of other brands of electrodes is not recommended as the quality of those products is unknown and it has been observed that the quality of the electrode may impact the ability of the Focus to operate efficiently, i.e., if the electrode does not adhere to the skin current will not be delivered.
## Intended Use:
As a TENS device, the Focus is indicated for the following conditions:
- symptomatic relief and management of chronic, intractable pain
- adjunctive treatment for post-surgical and post-trauma acute pain
As a NMS/NMES device, the Focus is indicated for the following conditions:
- relaxation of muscle spasm
- prevention or retardation of disuse atrophy
- increasing local blood circulation
- muscle re-education
- prevention of venous thrombosis of the calf muscles immediately after surgery
- maintaining or increasing range of motion
As a FES device, the Focus is indicated for the following condition:
- stimulation of the muscles in the leg and ankle of partially paralyzed patients to provide flexion of the foot and thus improve the patient’s gait
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# Comparison of Equivalent Devices to the New Device:
The Focus Model 795 is technically identical to the Focus 727 with the exception of a change in the LED lights from red to yellow. No testing is needed to establish equivalence.
The Focus Model 795 performs identically to the Focus 727 with the exception of an added function to prevent the stimulator from delivering current from a no output condition (no battery or device is turned OFF) to a rapid increase in current (fresh battery without turning the device OFF or manually turning the potentiometer up too quickly from start up of the device). This is an added “safety” feature which is required to meet international device standards. This function does not impact the performance of the device, thus does not require clinical testing to establish equivalence.
The Focus 795 also has a new indication for use, gait training, which makes the Focus indications for use equivalent to the indications for the Respond Select. This new indication is supported by the fact that these two products’ specifications are similar enough to be considered equivalent. See the comparison chart for specification details.
# Product Verification and Validation
The functional testing that was performed and analyzed against product specifications demonstrates that the product meets requirements and is acceptable for its intended use.
# Comparison of Product Specifications
See the following chart for details on the similarities and differences of the two predicate devices and the Focus device.
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COMPARISON OF PRODUCT SPECIFICATIONS
| Product Characteristics | Focus Model 795 | Focus Model 795 | Respond Select |
| --- | --- | --- | --- |
| No. Of Output Channels | 2 | 2 | 2 |
| Standards | AAMI/ANSI NS4-1985
IEC 601-2-10
IEC 601-1-2 | AAMI/ANSI NS4-1985
IEC 601-2-10
IEC 601-1-2 | AAMI/ANSI NS4-1985
IEC 601-2-10
IEC 601-1-2 |
| Current Range | 0-60mA (normal)
0-100mA (high) | 0-60mA (normal)
0-100mA (high) | 0-100 mA (alkaline)
0-90 mA (NiCd) |
| Maximum Output Voltage (1kΩ load) | ± 100 V * | ± 100 V * | ± 100 V * |
| Channel Interaction | ≤ 5% | ≤ 5% | ≤ 5% |
| Pulse Width | 300μs at 50% of peak amplitude | 300μs at 50% of peak amplitude | 300μs at 50% of peak amplitude |
| Waveforms* | Symmetrical biphasic or balanced asymmetrical biphasic | Symmetrical biphasic or balanced asymmetrical biphasic | Symmetrical biphasic or balance asymmetrical biphasic |
| Zero Net DC | yes controlled by transformer | yes controlled by transformer | yes controlled by transformer |
| Maximum Phase Charge (1kΩ load) | 30μC * | 30μC * | 30μC * |
| Pulse Rates | 25, 30, 35, 45, 50, 80 Hz | 25, 30, 35, 45, 50, 80 Hz | 1-80 Hz |
| ON Times | 2.5, 5, 10, 15, 20, 25, 30, 50 sec | 2.5, 5, 10, 15, 20, 25, 30, 50 sec | 2-60 sec, adjustable |
| OFF Times | 0, 5, 10, 15, 20, 25, 30, 50 sec | 0, 5, 10, 15, 20, 25, 30, 50 sec | 2-120 sec, adjustable |
| Ramp Time | 2 sec up, fixed
2 sec down, fixed
disabled with remote switch | 2 sec up, fixed
2 sec down, fixed
disabled with the remote switch | .2 - 10 sec up, adjustable
.1 - 5 sec down, adjustable
.4 sec up for gait protocol
1 sec down for gait protocol |
| Cycling Modes | synchronous(S) or alternating(A) | synchronous(S) or alternating(A) | synchronous or asynchronous |
| Timing Control Modes | continuous, normal operation, 15 or 30min, | continuous, normal operation, 15 or 30min, | continuous, 15, 30, 60min |
| Preprogrammed Regimens | 8 | 8 | 4 |
| High Output Shutdown (Output Interlock) | NO | YES | YES |
| Waveform Change Interlock | YES | YES | YES |
| Compliance Timer | NO | NO | YES |
| Accessories | Hand Held Remote or Heel Switch | Hand Held Remote or Heel Switch | Hand Held Remote or Heel Switch |
| Output Type | constant current
100Ω - 1kΩ | constant current
100Ω - 1kΩ | constant current
100Ω - 1kΩ |
| Minimum Electrode Size | Snapease: 0.79in²(5.1cm²) | Snapease: 0.79in²(5.1cm²) | Snapease: 0.79in²(5.1cm²) |
| Maximum RMS Current Density | 27.7mA/in² * | 27.7mA/in² * | 27.7mA/in² * |
| Maximum Phase Amplitude (specify load) | 100mA at 1kΩ * | 100mA at 1kΩ * | 100mA at 1kΩ * |
| Maximum Power Density | 607 mW/in² * | 607 mW/in² * | 607 mW/in² * |
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COMPARISON OF PRODUCT SPECIFICATIONS (cont.)
| Product Characteristics | Focus Model 727 | Focus Model 795 | Respond Select |
| --- | --- | --- | --- |
| Phase Duration Range | 300 μsec | 300 μsec | 300 μsec |
| Interface Interval | 500 μsec | 500 μsec | 30 μsec |
| Maximum Enclosure Leakage Current | 100μA | 100μA | 100μA |
| Automatic Overload Trip | NA | NA | NA |
| Automatic No Load Trip | NA | NA | NA |
| Patient Override Control | NA | NA | NA |
| Max. Patient Leakage Current | 100μA | 100μA | 100μA |
| Output Indicator | YES | YES | YES |
| Low Battery Indicator | YES | YES | YES |
| Size | 3.7x2.5x0.84 | 3.7x2.5x0.84 | 6x3.58x1.38 |
| Weight | 145 gm with battery | 145 gm with battery | 9.3 oz w/o battery |
| Power Source | 9 V Alkaline Battery | 9 V Alkaline Battery | 9 V Alkaline Battery |
| Controller | Microprocessor, masked | Microprocessor, masked | Application Specific Integrated Circuit |
| Housing Material | ABS Plastic | ABS Plastic | ABS Plastic |
| Indications for Use | As a TENS device, the 727 is indicated for the following conditions:
• symptomatic relief and management of chronic, intractable pain
• adjunctive treatment for post-surgical and post-trauma acute pain
As a NMS/NMES device, the Focus is indicated for the following conditions:
• relaxation of muscle spasm
• prevention or retardation of disuse atrophy
• increasing local blood circulation
• muscle re-education
• Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis
• maintaining or increasing range of motion | As a TENS device, the 795 is indicated for the following conditions:
• symptomatic relief and management of chronic, intractable pain
• adjunctive treatment for post-surgical and post-trauma acute pain
As a NMS/NMES device, the Focus is indicated for the following conditions:
• relaxation of muscle spasm
• prevention or retardation of disuse atrophy
• increasing local blood circulation
• muscle re-education
• Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis
• maintaining or increasing range of motion
As a FES device, the Focus is indicated for the following condition:
• stimulation of the muscles in the leg and ankle of partially paralyzed patients to provide flexion of the foot and thus improve the patient’s gait | As a NMS/NMES device, Respond Select is indicated for the following conditions:
• relaxation of muscle spasm
• prevention or retardation of disuse atrophy
• increasing local blood circulation
• muscle re-education
• Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis
• maintaining or increasing range of motion
As a FES device, the Focus is indicated for the following condition:
• stimulation of the muscles in the leg and ankle of partially paralyzed patients to provide flexion of the foot and thus improve the patient’s gait |
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.
