Smartphone App-Enabled Flex sEMG Patch using FOWLP

Surface electromyography (sEMG) is a technique in which electrodes placed on the surface of the skin record electric signals from muscle contraction. Data collected by the sEMG is instrumental in the diagnosis and treatment of neuromuscular diseases. Traditional sEMG systems require many wires and a complex setup. We have demonstrated a flexible sEMG called FlexsEMG that wirelessly transmits data through an embedded Bluetooth low energy (BLE) chip. FlexsEMG is based on the FlexTrate
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process. It utilizes die-first flexible fan-out wafer-level packaging (FOWLP) and solderless integration of bare dielets at 20-40 um pad pitches, allowing the device to bend to radii as small as 1 mm. The wireless setup enables a broader range of clinical applications at a lower cost. Previously, reported data was collected from a single subject and single device through a desktop computer and the data could not be displayed or processed in real time [1]. In this paper, we demonstrate: the prototyping of several FlexsEMG devices to evaluate repeatability of the process and identify potential problems; a newly developed mobile app to receive and display signals transmitted from our FlexsEMG devices in real time. We used this setup to collect data in real time from several participants with multiple devices demonstrating repeatability of the process and robustness of our devices. Further, our app allows the user to process the data after measurement and adjust any signal processing parameters as needed. Most importantly, it allows the use of the device in an ambulatory mode. Finally, we demonstrate the ability of our FlexsEMG platform to wirelessly collect sEMG data from multiple subjects performing a variety of physical activities with minimal setup time and complexity, suggesting consumer usage potential.