Hetero-core optical-fiber-based force myography sensor

Force myography (FMG) is a non-invasive technique to predict hand movements and intentions from radial pressures exerted by the forearm muscles. Although previous works introduced optical fiber sensors based on microbending and fiber Bragg grating probes for such applications, the available devices exhibit cost and sensitivity constraints. Therefore, this paper proposes a wearable sensor comprising a hetero-core fiber integrated into a smart textile. The transducer is comfortably accommodated in the user’s forearm with an armband, producing reliable optical loss signals as the muscular contractions bend the hetero-core section. Grip force experiments revealed a sensitivity of 1.58 × 10⁻² dB/kg for loads ≤ 20 kg. Furthermore, we investigated the sensor’s ability to discriminate four typical gestures for human-computer interfaces, achieving reliable single-channel performance by assessing the transient and stationary information of FMG waveforms. Such promising results motivate further applications in rehabilitation and human-robot interaction.