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To achieve dexterous motion controlling of robot, the sensors that function like human neurons for motion perception are essential. In this work, a silica microfiber probe-based optical neuron (MPON) for robot finger motion detection is proposed. The silica microfiber probe was fabricated by snapping a biconical silica optical microfiber that drawn from the standard optical fibre. Then it was embedded into thin polydimethylsiloxane (PDMS) to detect and recognize motions of robotic finger. Specifically, a PDMS-Teflon-Microfiber-Teflon-PDMS composite structure was prepared to protect the waveguide structure of silica microfiber probe and avoid the environmental pollution. With the help of this composite structure, the proposed MPON achieved the accurate measurement of bending angle with large range and fast response. The repeatability and stability of MPON were also investigated. Additionally, different finger motions were successfully distinguished through observing the output power variation of MPON. The proposed MPON could serve as the perceptron of robot hand, which could be applied in dexterous gesture control even human machine interaction.

Continuous monitoring of blood pressure has significant clinical value for the cardiovascular disease prevention and diagnosis in daily life. However, conventional blood pressure measurement is unsuitable for long-term monitoring due to its discomfort and poor portability. Wearable device is an ideal solution to overcome this problem, which has attracted increasing interests of many researchers. While, high-performance wearable blood pressure sensor still remains a challenge. Here, we present a wearable blood pressure wristband system based on optical fiber. The end face of optical fiber was coated with a Polydimethylsiloxane (PDMS) + Ag composite diaphragm. The continuous and accurate measurement of the pulse waveform was achieved through the phase variation of the light reflected from the diaphragm. Then, the blood pressure can be estimated from the pulse transit time (PTT) which is extracted from the high-fidelity pulse waveform. The estimation model was established using data from 45 subjects. The clinical experiment was also carried out on 17 subjects to test the performance of the proposed wearable blood pressure wristband. The results show that the errors of systolic pressure (SBP) and diastolic pressure (DBP) are 0.24 ± 2.39 mmHg and 0.12 ± 2.62 mmHg compared with commercial sphygmomanometer, respectively. The measurement errors were within the required range of the Association for the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS) Grade A, which indicates that the blood pressure wristband has a good accuracy and practicability. This wearable and user-friendly optical fiber blood pressure monitor is a competitive alternative to current commercial products.

A smart mattress based on optical fiber Mach-zender interferometer (OF-MZI) is designed for noninvasive and continuous monitoring of human vital signs. Through arranging the sensing fiber between two elastic covering layers with sandwich structure, the mattress was sensitive to the respiration and heartbeat induced micro-pressure. In the processing terminal, the waveforms of vital signs were demodulated by 3 * 3 coupler based differentiate and cross-multiplying method, and then four characteristic indicators including the heart rate, heartbeat amplitude, respiration rate, and respiration amplitude were respectively extracted through feature extraction algorithm, for evaluating the human health condition. Clinical experimental results of eighteen subjects indicate that the mattress system could not only distinguish the activity states of no body, on bed, body movement and off bed, but also contribute to clinical diagnosis of bradycardia, tachycardia, polypnea and apnoea. By adopting Bland–Altman analysis method, good reproducibility and accuracy were confirmed, where the max errors of heart rate and respiration rate are respectively 2 bpm and 1 bpm. Moreover, the responses at different positions of the mattress are identical and the continuous monitoring results in one day are consistent with daily change of vital signs, which proves that the fiber optic mattress has good reliability and stability. Beneficial from high-sensitivity, multiple parameters, long-term continuous monitoring, high comfortability and low cost, the mattress is promising in the early detection and prevention of cardiac and respiratory diseases as a household medical device.

We present a flexible silica-polymer composite optical fiber (SPCOF) inspired by fish lateral lines for underwater perception. The unique movement status of robotic fish and hydroacoustic signal with frequency of 100 Hz are detected.

A miniaturized ultrasound sensor based on optical fiber is designed and realized for multichannel parallel ultrasound detection and photoacoustic imaging. The fiber optic sensor is composed of a polymer coating, a reflective mirror and a single-mode optical fiber, with only 125 µm in diameter. By integrating the coherent demodulation technology and multiplexing technology, which using a relatively cheap fixed wavelength laser, hundreds of sensors could work simultaneously. Meanwhile, highly sensitive ultrasound detection has been demonstrated with the noise equivalent pressure as low as 0.46 kPa and the sensor exhibits a nearly omnidirectional directivity. Furthermore, a photoacoustic imaging system based on three sensors working in parallel is demonstrated. High lateral resolutions of 165-217 µm and axial resolutions of 112-131 µm over a depth range of larger than 5 mm are obtained. A three-dimensional phantom imaging experiment is also demonstrated. Benefited from parallel detection, the imaging speed is three times faster than that of a single sensor. The miniaturized fiber optic ultrasound sensor probe provides a competitive alternative for mechanically scanning-free endoscopic imaging, which is beneficial from small size, omnidirectional directivity and parallel detection capability.

A wearable device based on an alignment-free photonic chip (AFPC) which consists of optical microfiber and flexible liquid chip for precise human health monitoring was developed. High-fidelity physiological signals and vital signs were detected and extracted for cardiovascular health accessment.

A microfiber probe-based wearable sensor is proposed and demonstrated. Based on the flexibility and high sensitivity of microfiber, the sensor can measure the joint motion and the pulse wave for health monitoring.

A highly sensitive and compact fiber optic ultrasound sensor based on a composite sensing film is demonstrated. Assisted with the coherent demodulation, a NEP of 0.46kPa and the bandwidth of 20MHz are successfully achieved.

We present a wearable blood pressure wristband based on optical fiber probe with composite diaphragm. Clinical results show errors of systolic pressure and diastolic pressure are 0.24 ± 2.32 mmHg and 0.18 ± 2.48 mmHg.

An ultra-sensitive optical microfiber ultrasonic sensor is proposed and demonstrated. The noise equivalent pressure length product of this sensor is 1.71kPa mm, which gives a 53 times improvement compared with standard single-mode fiber.

The determination of hemoglobin (Hb) level is indispensable in the pathological study of many blood diseases. Graphene oxide (GO), with its excellent optical properties and great biocompatibility, has attracted significant attention and been widely utilized in biochemical detection. Here, we report an ultrasensitive Hb sensor based on a graphene oxide (GO)-coated microfiber. The GO was utilized as a linking layer deposited on the microfiber surface, which can provide an enhanced local evanescent light field and abundant bonding sites for Hb molecules. The optical microfiber with a compact structure and a strong evanescent light field served as the platform for biosensing. The surface morphology characterized by optical microscope, scanning electron microscope, and Raman spectroscopy offers detailed evidence for the success of GO deposition. The dynamic bonding between GO and target Hb molecules was monitored in real-time through an optical spectrum analyzer. An ultrahigh sensitivity of 6.02 nm/(mg/mL) with a detection limit of 0.17 &mu, g/mL was achieved by tracking the resonant wavelength shift of spectra. It is important to highlight that the detection limit of GO-coated microfiber is 1&ndash, 2 orders of magnitude lower than other reported fiber optic Hb sensors. Benefiting from high sensitivity, low cost, small size, and fast response, the proposed sensing microfiber coated with GO could be a competitive alternative in the diagnosis of blood diseases and a subject of further research in the medical field.

In this article, we have theoretically and experimentally investigated the unique vector refractive index (RI) sensing property of tilted fiber grating (TFG). Due to the orthogonal symmetric grating structure, TFGs would mainly achieve the coupling between the fiber core mode and the two orthogonal polarization LP1m of cladding mode. And the numerical simulation results showed that the coupling coefficient between fundamental core mode to the LP1m cladding mode is higher than the others. In the experiment, we have furthermore observed the cladding mode field distribution of excessively TFG (Ex-TFG) and long period fiber grating (LPFG), which indicated that the evanescent field distribution of cladding mode of TFG shows an asymmetric near field distribution with two lobes oriented along the fast axis of TFG, and the one of LPFG has a circularly symmetric cladding mode field distribution. In addition, by employing side-immersion method, we have measured the azimuth RI sensitivities of Ex-TFG, tilted fiber Bragg grating (TFBG) and LPFG, which exhibited that both Ex-TFG and TFBG have shown a direction-dependency RI sensitivity, and the RI sensitivity with side-immersion along fast axis is almost half of the one along slow axis, and the RI sensitivity of LPFG is azimuth independent. Overall, the experiment results show that the TFGs inherently show unique directional RI sensing property, which could be potentially applied in vector sensing area.