TissueDB/Simulators/Knot Tying Force-Feedback Simulator (Amiel)
General Information
The Amiel Knot Tying Force-Feedback Simulator ("Knoti") is a bench-top instrument that measures the force a trainee applies while tying a one-handed square knot for vessel ligation and signals, in real time, when that force is high enough to risk tearing tissue or thread.[1]
| Field | Details |
|---|---|
| General Information | A bench-top, force-feedback trainer for one-handed square knot tying in vessel ligation. It is a force-measurement instrument rather than an anatomical tissue model. As described in Amiel et al. 2020 (PMID 31806168).[1] |
| Features and Basic Operation | The device has four parts: a hook where the knot is tied (A); a clear plexiglass tube placed over the hook to recreate the depth of a deep surgical field, with its top set 3 cm above the hook (B); a data sensor that measures the vertical reaction force and logs it to a computer over USB (C); and a feedback unit with red and green LEDs and a beeper (D). As the trainee ties a knot, a green LED with an intermittent beep indicates force below 1.3 N and a red LED with a continuous beep warns when force exceeds 1.3 N — the maximum force exerted by expert surgeons, established in the authors' earlier study.[1][3] The software records total force, peak pulling and pushing force, and completion time for each knot.[1] |
| Current Development Status | Built and tested for training efficacy; full results in Amiel et al. 2020.[1] |
| Estimated Build Time and Cost | Not stated in source., Not stated in source. |
| Specialized Tools and Equipment | Personal computer running the device's data-logging software (written in Processing; data analysed in MATLAB, per Laufer et al. 2016).[2] Consumables for use: 3-0 silk suture (the source used Sofsilk 3.0, Medtronic) and surgical gloves.[1] |
| Version | As described in Amiel et al. 2020 (American Journal of Surgery 220(1):100–104).[1] |
| Development Team Contact Information | Imri Amiel, Roi Anteby, Moti Cordoba, Shlomi Laufer, Chaya Shwaartz, Danny Rosin, Mordechai Gutman, Amitai Ziv and Roy Mashiach, of the Faculty of Medicine, Tel Aviv University; Sheba Medical Center (Tel-Hashomer, Ramat-Gan); the Israel Center for Medical Simulation (MSR); and the Technion – Israel Institute of Technology (Haifa). Corresponding author: Roi Anteby (roianteby@mail.tau.ac.il).[1] |
Structural Parts
| Part Name | Qty | Material | Cost | Notes |
|---|---|---|---|---|
| Hook (component A) | 1 | Material not specified in source | Not reported | The point where the knot is tied, representing a vessel-ligation site. Material and dimensions are not specified in Amiel et al. 2020.[1] |
| Plexiglass tube (component B) | 1 | Plexiglass (acrylic) | OD 5.1 cm × ID 4.4 cm × wall 0.35 cm (Laufer et al. 2016); total length not stated | Placed over the hook to recreate the depth of a deep surgical field; positioned so its top sits 3 cm above the hook, and removable.[2][1] |
| Data sensor (component C) | 1 | Strain-gauge load cell (Micro-Measurements foil gauges) | Aluminium sheet 2.54 × 12.7 × 0.16 cm (Laufer et al. 2016) | Measures the vertical reaction force using four strain gauges in a Wheatstone bridge; connects to an Arduino Uno and logs to a computer over USB (sampled at 60 Hz, 10 N range). Sensor resolution not stated.[2][1] |
| Feedback appliance (component D) | 1 | LED and buzzer circuit (specifications not stated) | Not reported | Red LED with a continuous beep above 1.3 N; green LED with an intermittent beep below it. Circuit schematic and parts are not specified in the source.[1] |
Build Instructions
Phase 1: Obtain Components
Construction details for the Knoti device are not fully provided in Amiel et al. (2020). The 2020 paper is a validation study of an existing device; hardware specifications are documented in the original development papers: Laufer et al. (2016)[2] and Amiel et al. (2019).[3] The four components are:
- Obtain or fabricate the hook (component A) for knot application. Material and dimensions not specified in the 2020 paper.[1]
- Obtain or fabricate the plexiglass tube (component B). Position so that the top of the tube is 3 cm above the top of the hook.[1]
- Obtain the data sensor (component C) with USB connection to a personal computer. Brand, model, and specifications deferred to Laufer et al. 2016.[2]
- Obtain or fabricate the feedback appliance (component D) with red/green LED lights and alarm circuit calibrated to the 1.3 N force threshold. Circuit specifications deferred to Laufer et al. 2016.[2]
Phase 2: Assemble the Device
- Mount the hook (A) on the base platform (visible in Fig. 1 but base dimensions and material not specified in source).
- Position the plexiglass tube (B) over the hook so the top of the tube is 3 cm above the hook top.[1]
- Connect the data sensor (C) to the hook assembly to measure reaction forces in the vertical axis.
- Connect the data sensor to a personal computer via USB cable.
- Mount the feedback appliance (D) adjacent to the hook/tube assembly.
- Connect the feedback appliance to the data sensor circuit with the 1.3 N threshold programmed.[1]
Phase 3: Verify Function
- Launch the designated computer software and confirm USB connection to the data sensor.
- Tie a test knot (3-0 silk suture, one-handed square knot technique) on the hook inside the plexiglass tube.
- Observe the green LED and intermittent beep when reaction force is below 1.3 N.
- Observe the red LED and persistent beep when reaction force exceeds 1.3 N.
- Check the software logs for total force, maximum pulling force, maximum pushing force, and completion time.[1]
Not Suitable For
The Amiel Knot Tying Force-Feedback Simulator trains one-handed square knot tying for vessel ligation with vertical-axis force feedback. Beyond that scope:
- Lateral or multi-axis force measurement — the sensor measures the vertical axis only; the authors acknowledge this limitation.[1]
- Knot integrity testing under mechanical load — knot quality was checked visually by an examiner, not by tensile testing.[1]
- Use with attending surgeons or medical students — the validation cohort was PGY 1-2 surgical residents only.[1]
- Tissue-model fidelity — the authors note the target force was derived from expert performance, not from tissue models measuring tear forces.[1]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 Amiel I, Anteby R, Cordoba M, Laufer S, Shwaartz C, Rosin D, Gutman M, Ziv A, Mashiach R (2020). "Feedback based simulator training reduces superfluous forces exerted by novice residents practicing knot tying for vessel ligation." American Journal of Surgery 220(1):100–104. DOI: 10.1016/j.amjsurg.2019.11.027. PMID: 31806168.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Laufer S, Amiel I, Nathwani JN, Mashiach R, Margalit RS, Ray RD, Ziv A, Pugh CM (2016). "A Simulator for Measuring Forces During Surgical Knots." Studies in Health Technology and Informatics 220:199–204. DOI: 10.3233/978-1-61499-625-5-199. PMID: 27046578. Original Knoti device hardware description.
- ↑ 3.0 3.1 3.2 Amiel I et al. (2019). Surgery 2020 Apr. DOI: 10.1016/j.surg.2019.09.017. PMID: 31685234. Construct validity study establishing the 1.3 N expert force threshold (n=45: 15 experts + 30 residents).
| Alternative names | Knoti (the device name used throughout the source paper) |
|---|
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| Authors | Arturopelayo |
|---|---|
| License | CC-BY-SA-4.0 |
| Cite as | Arturopelayo (2026). "TissueDB/Simulators/Knot Tying Force-Feedback Simulator (Amiel)". Appropedia. Retrieved June 4, 2026. |