{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T05:48:54Z","timestamp":1791611334237,"version":"4.3.4"},"reference-count":34,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2025,12,10]],"date-time":"2025-12-10T00:00:00Z","timestamp":1765324800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan","award":["BR24992820"],"award-info":[{"award-number":["BR24992820"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Affordable, sensor-driven lower-limb prostheses remain scarce in middle-income health systems. We report the design, numerical justification, and bench validation of a semi-active transfemoral prosthesis featuring surface electromyography (EMG) control and inertial sensing for low-resource deployment. The mechanical architecture combines a titanium\u2013aluminum\u2013carbon composite frame (total mass 0.87 kg; parts cost &lt; USD 400) with topology optimization (SIMP) to minimize weight while preserving stiffness. Finite-element analyses (critical load 2.94 kN) confirmed structural safety (yield safety factor \u2265 1.6) and favorable fatigue margins. A dual-channel sensing scheme\u2014surface EMG from the rectus femoris and an IMU\u2014drives a five-state gait finite state machine implemented on a low-power STM32H platform. The end-to-end EMG\u2192PWM latency remained &lt;200 ms (mean 185 ms). Bench tests reproduced commanded flexion within \u00b12.2%, with average electrical power of ~4.6 W and battery autonomy of ~5.7 h using a 1650 mAh Li-Po pack. Results demonstrate a pragmatic trade-off between functionality and cost: semi-active damping with EMG-triggered control and open, modular hardware suitable for small-lab fabrication. Meeting target metrics (mass \u2264 1 kg, latency \u2264 200 ms, autonomy \u2265 6 h, cost \u2264 USD 500), the prototype indicates a viable pathway to broaden access to intelligent prostheses and provides a platform for future upgrades (e.g., neural network control and higher-efficiency actuators).<\/jats:p>","DOI":"10.3390\/s25247505","type":"journal-article","created":{"date-parts":[[2025,12,10]],"date-time":"2025-12-10T15:32:17Z","timestamp":1765380737000},"page":"7505","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Design and Testing of an Emg-Controlled Semi-Active Knee Prosthesis"],"prefix":"10.3390","volume":"25","author":[{"given":"Kassymbek","family":"Ozhikenov","sequence":"first","affiliation":[{"name":"Department of Robotics and Technical Tools of Automation, Satbayev University, Almaty 050013, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9712-5592","authenticated-orcid":false,"given":"Yerkebulan","family":"Nurgizat","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abu-Alim","family":"Ayazbay","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-6728-0748","authenticated-orcid":false,"given":"Arman","family":"Uzbekbayev","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aidos","family":"Sultan","sequence":"additional","affiliation":[{"name":"Department of Robotics and Technical Tools of Automation, Satbayev University, Almaty 050013, Kazakhstan"},{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arailym","family":"Nussibaliyeva","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nursultan","family":"Zhetenbayev","sequence":"additional","affiliation":[{"name":"Department of Robotics and Technical Tools of Automation, Satbayev University, Almaty 050013, Kazakhstan"},{"name":"Department of Electronic Engineering, Almaty University of Power Engineering and Telecommunications Named Gumarbek Daukeyev, Almaty 050062, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raushan","family":"Kalykpaeva","sequence":"additional","affiliation":[{"name":"Department of Robotics and Technical Tools of Automation, Satbayev University, Almaty 050013, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2762-473X","authenticated-orcid":false,"given":"Gani","family":"Sergazin","sequence":"additional","affiliation":[{"name":"Department of Science and Innovations, ALT University Named After Mukhamedzhan Tynyshpaev, Almaty 050013, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Yuan, B., Hu, D., Gu, S., Xiao, S., and Song, F. (2023). The global burden of traumatic amputation in 204 countries and territories. Front. Public Health, 11.","DOI":"10.3389\/fpubh.2023.1258853"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"02024","DOI":"10.1051\/e3sconf\/202338102024","article-title":"Analysis of factors affecting the severity of car accidents in the Akmola region of Kazakhstan","volume":"381","author":"Mukhamadeyeva","year":"2023","journal-title":"E3S Web Conf."},{"key":"ref_3","first-page":"e2024130","article-title":"The prevalence of diabetes mellitus in Kazakhstan: A systematic review and meta-analysis","volume":"95","author":"Kazbekova","year":"2024","journal-title":"Acta Biomed."},{"key":"ref_4","unstructured":"Ministry of Health of the Republic of Kazakhstan (2025, May 28). Statistics on Disability and Assistive Technology Provision, Available online: https:\/\/www.gov.kz\/memleket\/entities\/dsm."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"452","DOI":"10.23736\/S1973-9087.22.07238-0","article-title":"Impact of Microprocessor Prosthetic Knees on Mobility and Quality of Life in Patients with Lower-Limb Amputation: A Systematic Review","volume":"58","author":"Thibaut","year":"2022","journal-title":"Eur. J. Phys. Rehabil. Med."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Qadir, A., Zahran, A., Vatankhah, R., Javed, K., Sharayan, M., Atif, M., Ahmed, B., Hong, K.-S., Kim, H., and Ali, S. (2024). Design, Analysis, and Development of Low-Cost State-of-the-Art Magnetorheological-Based Microprocessor Prosthetic Knee. Sensors, 24.","DOI":"10.3390\/s24010255"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1109\/TMRB.2023.3282325","article-title":"Electromyography-based control of lower limb prostheses: A systematic review","volume":"5","author":"Ahkami","year":"2023","journal-title":"IEEE Trans. Med. Robot. Bionics"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1177\/0278364907084588","article-title":"Design and control of a powered transfemoral prosthesis","volume":"27","author":"Sup","year":"2008","journal-title":"Int. J. Robot. Res."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Au, S.K., Herr, H., Weber, J., and Martinez-Villalpando, E.C. (2007, January 22\u201326). Powered ankle-foot prosthesis for the improvement of amputee ambulation. Proceedings of the 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Lyon, France.","DOI":"10.1109\/IEMBS.2007.4352965"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"60","DOI":"10.3390\/prosthesis4010007","article-title":"Design and Initial Evaluation of a Low-Cost Microprocessor-Controlled Above-Knee Prosthesis: A Case Report of 2 Patients","volume":"4","author":"Galey","year":"2022","journal-title":"Prosthesis"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1109\/TNSRE.2013.2285101","article-title":"A training method for locomotion mode prediction using powered lower limb prostheses","volume":"22","author":"Young","year":"2013","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Vujaklija, I., and Farina, D. (2023). Prosthetics and Innovation. Blast Injury Science and Engineering: A Guide for Clinicians and Researchers, Springer.","DOI":"10.1007\/978-3-031-10355-1_41"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1109\/TBME.2010.2070840","article-title":"Volitional control of a prosthetic knee using surface electromyography","volume":"58","author":"Ha","year":"2010","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/1743-0003-12-1","article-title":"Control strategies for active lower extremity prosthetics and orthotics: A review","volume":"12","author":"Tucker","year":"2015","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_15","first-page":"3049","article-title":"Optimal design of flow mode semi-active prosthetic knee dampers","volume":"29","author":"Saini","year":"2022","journal-title":"Sci. Iran."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1186\/1743-0003-6-21","article-title":"Exoskeletons and orthoses: Classification, design challenges and future directions","volume":"6","author":"Herr","year":"2009","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_17","unstructured":"Narayan, R. (2018). Encyclopedia of Biomedical Engineering, Elsevier."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"172537","DOI":"10.1016\/j.jmmm.2024.172537","article-title":"Trajectory tracking control of a four-bar linkage prosthetic knee with magnetorheological damper","volume":"610","author":"Zhang","year":"2024","journal-title":"J. Magn. Magn. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e25","DOI":"10.1017\/wtc.2023.20","article-title":"Series-elastic actuator with two degree-of-freedom PID control improves torque control in a powered knee exoskeleton","volume":"4","author":"Sarkisian","year":"2023","journal-title":"Wearable Technol."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Maag, C., Fitzpatrick, C.K., and Rullkoetter, P.J. (2025). Evaluation of machine learning techniques for real-time prediction of implanted lower limb mechanics. Front. Bioeng. Biotechnol., 12.","DOI":"10.3389\/fbioe.2024.1461768"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1016\/j.arcontrol.2023.03.003","article-title":"A review of current state-of-the-art control methods for lower-limb powered prostheses","volume":"55","author":"Gehlhar","year":"2023","journal-title":"Annu. Rev. Control"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1242","DOI":"10.1007\/s42235-022-00169-1","article-title":"Intelligent knee prostheses: A systematic review of control strategies","volume":"19","author":"Li","year":"2022","journal-title":"J. Bionic Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e00564","DOI":"10.1016\/j.ohx.2024.e00564","article-title":"Open-source design of low-cost sensorised elastic actuators for collaborative prosthetics and orthotics","volume":"19","author":"Sanfilippo","year":"2024","journal-title":"HardwareX"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"953","DOI":"10.1177\/0278364918785993","article-title":"Design, development, and testing of a lightweight hybrid robotic knee prosthesis","volume":"37","author":"Lenzi","year":"2018","journal-title":"Int. J. Robot. Res."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Zhang, Z., Yu, H., Cao, W., Wang, X., Meng, Q., and Chen, C. (2021). Design of a semi-active prosthetic knee for transfemoral amputees: Gait symmetry research by simulation. Appl. Sci., 11.","DOI":"10.3390\/app11125328"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Mu\u00f1oz-V\u00e1squez, S., Mora-P\u00e9rez, Z.A., Ospina-Henao, P.A., Valencia-Ni\u00f1o, C.H., Becker, M., and D\u00edaz-Rodr\u00edguez, J.G. (2023). Finite Element Analysis in the Balancing Phase for an Open Source Transfemoral Prosthesis with Magneto-Rheological Damper. Inventions, 8.","DOI":"10.3390\/inventions8010036"},{"key":"ref_27","unstructured":"(2013). Standard Specification for Wrought Titanium-6Aluminum-4Vanadium Alloy for Surgical Implant Applications (UNS R56400) (Standard No. ASTM F1472)."},{"key":"ref_28","unstructured":"(2016). Prosthetics\u2014Structural Testing of Lower-Limb Prostheses (Standard No. ISO 10328:2016)."},{"key":"ref_29","unstructured":"(2009). Non-Active Surgical Implants\u2014Partial and Total Knee-Joint Prostheses (Standard No. ISO 21535:2009)."},{"key":"ref_30","unstructured":"(2020). Prosthetics and Orthotics\u2014Vocabulary\u2014Part 1: General Terms for External Limb Prostheses and External Orthoses (Standard No. ISO 8549-1:2020)."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Posada-Borrero, A.M., Pati\u00f1o-Lugo, D.F., Plata-Contreras, J.A., Velasquez-Correa, J.C., and Lugo-Agudelo, L.H. (2022). Development of a clinical practice guideline for lower limb amputees. A knowledge translation process in a middle income country. Front. Rehabil. Sci., 3.","DOI":"10.3389\/fresc.2022.873436"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.apmr.2023.07.012","article-title":"Epidemiology of limb amputations and prosthetic use during COVID-19 pandemic in the Netherlands","volume":"105","author":"Rommers","year":"2024","journal-title":"Arch. Phys. Med. Rehabil."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Creveling, S., Cowan, M., Sullivan, L.M., Gabert, L., and Lenzi, T. (2023, January 1\u20135). Volitional EMG control enables stair climbing with a robotic powered knee prosthesis. Proceedings of the 2023 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Detroit, MI, USA.","DOI":"10.1109\/IROS55552.2023.10341615"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"eabo3996","DOI":"10.1126\/scirobotics.abo3996","article-title":"A lightweight robotic leg prosthesis replicating the biomechanics of the knee, ankle, and toe joint","volume":"7","author":"Tran","year":"2022","journal-title":"Sci. Robot."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/25\/24\/7505\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,12]],"date-time":"2025-12-12T12:53:30Z","timestamp":1765544010000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/25\/24\/7505"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,10]]},"references-count":34,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["s25247505"],"URL":"https:\/\/doi.org\/10.3390\/s25247505","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,10]]}}}