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Engineering Innovation: Mobile EMG Update

Updated: Jun 4, 2020

A new week brings a new blog post! Last week I spoke with Khilesh, a recent mechanical engineering graduate on our team, to dive into the nitty-gritty of the technology we are developing. I am excited to tell you about the innovation and patient considerations that have informed his work. Khilesh has been working specifically on our mobile EMG (electromyography) sensor. This sensor is small but mighty, and has the potential to revolutionize both in-person and remote assessments.

Gathering information about a patient’s force, or strength, is essential for many rehabilitation assessments. The EMG sensor utilizes Newton’s third law: for every action there is an equal and opposite reaction. The sensor records electrical energy that is generated by muscle movements and its programming counterpart converts this data into a measurement of force. Our working prototype is designed specifically for shoulder assessments. To use the device the clinician will wear the electrodes on their biceps and triceps. The clinician will then perform the assessment by having the patient perform specific movements.

While the patient performs these movements the clinician will have the patient push against their arm with the device on it. The voltage of the patient's force will be transmitted to the device. The program then collects this data and using the specific triceps-biceps force ratio for that assessment, will record the patient’s strength. Over time, this data will be used to monitor progress and intervention success.

Early prototype of the EMG device using wet electrodes. This device is worn on the arm by the clinician.

In a “normal” face-to-face rehabilitation assessment a clinician is able to test a patient’s strength by having them push against their hand, but this poses a problem for virtual assessment. One idea is that the generalist clinician could relay their idea of the patient’s strength to the specialist, but that is incredibly subjective and not an accurate measurement. Using the EMG device allows for precise, universal measurements in real time which benefit both patient and clinician. The device solves the ambiguity problem which could be encountered in a virtual assessment and removes clinician bias. This makes using the sensor even during in-person assessments a valid idea. Using the sensor’s measurements improves accuracy and can in turn improve treatment plans. The device provides objective data which can differentiate small changes and detect progress of interventions easily.

There has been considerable progress on the sensor in the last few weeks. The device and programming is becoming more accessible and user-friendly everyday. Since Khilesh came onboard the project in January he has been testing the sensor and tweaking programming with a focus on experiences of the client and patient. Importantly, we have switched from wet to dry electrodes. This switch has drastically improved practicality. Prior to this switch five wet electrodes were needed, but with the dry electrodes only one is needed. The transmitter is also now stable for a full assessment length and there is no loss of connection. The app which corresponds with the device has also seen substantial advancements. The analysis and review features will provide patients with statistics and data such as percent improvement since beginning an intervention and a graph of their strength over time. This feature is important from a clinical point of view, but it is also important to patients so they can see their progress and are motivated to continue their assessments.

Screen grab of the app used in conjunction with the EMG sensor. The 'Review' tab of the app is where patients can find their progress data and statistics.

The EMG device prototype, the app, and corresponding programming has come a long way since we began developing it. It is nearly ready to be tested in a clinical setting as our trials get underway soon. We are also working on creating a Standard Operating Procedure (SOP) for the device. In the future we plan to develop the device to be commercially available and used for other assessment types. This technology creates an opportunity for a future of rehabilitation assessments that are more rigorous and provide better care to patients. I am looking forward to hearing the experience of patients and clinicians who use the device in our trials!

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