Packaged Elastomeric Optical Fiber Sensors for Healthcare Monitoring and Human‐Machine Interaction

Abstract

Elastomeric polymer optical fiber (EPOF) enabled flexible optical sensors have been attracting intensive research interest due to their excellent stretchability, sensing performance, and anti‐electromagnetic interference. However, a soft EPOF without effective protection tends to be damaged, which may undermine its long‐term stability, and thus, limit its practical applications. In this work, a strategy for packaging a section of EPOF is proposed, a light‐emitting diode (LED), and a photodiode (PD) into a stretchable and flexible silicone patch for both healthcare and human‐machine interaction applications. The silicone package not only protects the EPOF from environmental disturbance, providing a compact sensing approach for conformal attachment on flexible or curved surfaces but also offers an effective manner to adjust the sensitivity and working range of the EPOF sensors. Typically, an EPOF sensor is sensitive to pressure, strain, or bending. As a proof‐of‐concept demonstration, a laryngoscope equipped with a packaged EPOF sensor that can bear a pressure of 60 MPa is developed. It can effectively avoid teeth damage by real‐time monitoring the contact force during the operation. Furthermore, a data glove with five packaged EPOF sensors for hand gesture recognition and remote control of a micro‐vehicle is fabricated.

Soft Polymer Optical Fiber Sensors for Intelligent Recognition of Elastomer Deformations and Wearable Applications

“…It is found that the sensor is not quite sensitive to a small bending angle < 20 • , which can be attributed to the large numerical aperture (0.5) of POF and the small gap distance [20]. In the linear bending response range (30-60 • ), the derived sensitivity is −2.1%/ • and is comparable to the recently reported soft fiber sensors [20,22]. The bending sensitivity can be improved by simply tuning the air gap distance, although the effective angle range detection can be compromised [20].…”

“…As shown in Figure 2a, the normalized transmitted light intensity significantly decreases with increasing strain, and the repeatability is reasonably good for practical applications. We define strain sensitivity as S = ∆I/ε, where ∆I is the change in normalized intensity and ϵ is the change in strain [17,22]. Thus, the extracted strain sensitivity is approximately −0.2.…”

“…Despite these recent advances, the conventional silica fiber sensors show a small dynamic range of mechanical deformation limited by the strength of the silica material, although extra structure design can improve the performance [11]. For soft robotic sensing applications, the optical sensors based on polymer materials have natural advantages since their mechanical modulus is close to human tissues, and they have better biocompatibility and stretchability [10,11,22,23]. Zhao et al [14], reported an optoelectronically innervated soft prosthetic hand by using stretchable optical waveguides.…”