Frequently Asked Questions

🧲 Hardware

    • Hamstrings or calf: Use the 2-sensor strap variant.

    • Quadriceps: Use the 3-sensor strap variant.

    • Single muscle: Use the 1-sensor strap variant.

    • Insert each BioSensr into its slot, ensuring the alignment ridges click into place.

    • You may need to slightly bend the strap to help the BioSensr lock in securely.

  • Use Spectra 360 electrode gel:

    1. Squeeze gel into each cavity until it’s about ¾ full.

    2. If re-using the sensor between people, wipe away excess gel with a paper towel.

    3. You don’t need to remove all the gel between uses—just keep the surface clean.

    1. Place the strap centrally over the target muscle body (e.g., middle of the hamstring).

    2. The BioSensr logo should face upright, toward the head.

    3. Fasten the strap snugly but comfortably—it should not restrict movement or blood flow.

    💡 Tip: Shave excess hair for consistent readings.

💻 Software

  • 1. System Requirements

    • Mac: macOS with M1 processor or higher; latest MATLAB Runtime (arm64)

    • Windows: Windows 10 or higher (64-bit, preferably ARM); latest MATLAB Runtime (64-bit)

    2. Installation Instructions (Mac)

    1. Save BioSensr_Installer in your Downloads folder

    2. Before proceeding, delete any previous installations by going to Finder → Applications → BioSensr and removing the app.

    3. Fix the “Damaged App” Message

      When opening BioSensr_Installer, macOS may display:

      | “BioSensr_Installer” is damaged and can’t be opened. You should move it to the Bin.

      This happens because the app isn’t signed. To fix:

      • Open Terminal

      • Paste and run the following commands:

        cd Downloads

        xattr -d com.apple.quarantine BioSensr_Installer.app

    4. Open BioSensr_Installer

      When prompted that “MATLABRuntimeInstaller wants to make changes”, enter your password to allow this.

    5. Run through the installation — it will install MATLAB Runtime, and then BioSensr.

    6. Open BioSensr

      BioSensr is now installed.

    3. Installation Instructions (Windows)

    1. Before proceeding, uninstall any previous version of BioSensr

    2. Open BioSensr_Installer.exe

    3. Fix the Security Prompt

      Windows may display a security warning.

      Select “More info” → “Run anyway” to confirm that you trust the program.

    4. Run through the installation — it will install MATLAB Runtime, and then BioSensr.

    5. Open BioSensr

      BioSensr is now installed.

    1. Open BioSensr.

    2. Click the Settings (⚙️) icon to:

      • Choose the data save path

      • Open the athlete table (CSV) to edit athlete names and de-identified IDs

      • Enable or disable auto-switch sides (automatically switches between left/right)

      • Set the measurement history range (in months)

      • Click Save Settings when done

    1. Select the Exercise and Athlete from the dropdown menus.

    2. Plug the Metal USB-C Hub into your computer (but keep all sensors unplugged).

    3. Click Connect. The software will prompt you to plug in each sensor in order (e.g., Teal → Blue → Orange → Yellow)

    4. Use the Left / Right slider to choose which side of the body you’re testing.

    5. Position the athlete for the isometric hold (see Exercise section below).

    6. Click Measure. The program will guide the sequence:

      • Relax (3 seconds)

      • Go: Maximum voluntary contraction (MVC) for 3 seconds

      • Relax (3 seconds)

    1. Measurement Panel (Top Left):

      Shows the measurement in real time or from past sessions. Measurements are normalised to MVC, with percentages recorded from the first peak to three seconds post-peak.

    2. Signal Panel (Top Right):

      Shows the raw EMG signal in real time or from past sessions.

    3. Measurement History (Bottom):

      Displays performance trends over months and highlights best results within the selected timeframe.

      Click a data point to load its full measurement.

💡 Tip: Run BioSensr on laptop battery power to minimise electromagnetic interference. If noise persists, have the athlete lightly grip the metal USB-C hub.

🏋 Exercises

  • Muscles: Biceps Femoris & Semitendinosus

    Set-up Options:

    • Default setup: VALD NordBord (gold standard)

    • Alternative setup: Use squat rack spotter bars or similar restraint

    Form tips:

    • Lie prone

    • Strap at base of ankle

    • Knee at 90°

    • Ensure neutral hip alignment

  • Muscles: Biceps Femoris & Semitendinosus

    Ideal for field testing when a NordBord is unavailable.

    Note: It can be difficult to reach true MVC; focus on maximal stable contraction.

  • Muscles: Vastus Lateralis, Rectus Femoris, Vastus Medialis

    Back flat against the wall, single leg at 90°, other leg raised.

    Ensure consistent knee angle and avoid shifting load during the test.

  • Muscles: Vastus Lateralis, Rectus Femoris, Vastus Medialis

    Use a knee extension machine or resistance band setup.

    Ensure the same joint angle and tension between tests for comparability.

  • Muscles: Gastrocnemius (lateral & medial)

    Stand on one leg with toes on a step, heel off edge. Hold top position (max contraction) for the duration.

  • If you need to measure a muscle or exercise not listed, please consult BioSensr support before testing.

    Unlisted exercises are primarily for research or validation purposes.

    💬 Note: Always consult your physiotherapist or S&C coach before implementing new tests.

💡 Tip: The Single-Leg Isometric Hamstring Hold targets the hamstrings. It’s used for performance monitoring, not injury diagnosis.

Note: BioSensr and this test are not a medical device and are for performance monitoring only.

🧽 Cleaning & Maintenance

    1. Remove BioSensr from the straps.

    2. Rinse electrode cavities under running water.

    3. Clean gently with a sponge.

    4. Avoid getting water in the USB-C port—if it does, dry thoroughly using an air dryer.

    5. Wipe BioSensr dry with a cloth or microfibre towel.

    • Wash occasionally on a cold cycle in a laundry bag.

    • Standard detergent is fine.

    • Each strap is securely bonded to the BioSensr holder with a high-strength, durability-tested adhesive.

    • Air dry only — do not tumble dry.

🧤 Durability & Handling

  • BioSensr is designed for high performance and longevity:

    • Bend tested: 100,000 cycles

    • Drop tested: Up to 2 metres

    • Tensile strength: 10 kg (Instron tested)

    • Maximum strain: 50 % (Instron tested)

    Despite their robustness, handle the BioSensr device with care and avoid twisting or pulling.

  • For accurate EMG readings, minimise electrical noise and interference during measurements:

    • Unplug your laptop from mains power and operate on battery.

    • Ensure no-one is touching the athlete during testing — even light contact can introduce noise or ground loops.

    • Keep sensors and cables away from power boards, chargers, and fluorescent lights.

    • Avoid nearby Wi-Fi routers, phones on charge, and plugged-in electronics.

    • If noise persists, have the athlete lightly grip the metal USB-C hub.

🛠️ Troubleshooting & Support

    • Ensure all sensors are unplugged when clicking Connect.

    • Follow the on-screen colour order prompts.

    • Check that the USB-C hub is detected by your computer.

    • Try a different port or cable if issues persist.

    • Ensure the laptop is unplugged from mains power. If noise persists, have the athlete lightly grip the metal USB-C hub.

    • Ensure good skin contact and adequate gel.

    • Tighten the strap slightly.

    • Clean electrodes if gel has dried.

    • Verify correct sensor orientation.

  • Reach out to BioSensr Support for hardware or software assistance: jett@biosensr.com