摘要：近日，香港大学褚智勤团队和南方科技大学李携曦团队以「A versatile optoelectronic device for ultrasensitive negative-positive pressure sensing 」¹为题在Chip上发表研究论文

近日，香港大学褚智勤团队和南方科技大学李携曦团队以「A versatile optoelectronic device for ultrasensitive negative-positive pressure sensing 」¹为题在Chip上发表研究论文，通过探索反射光栅对单片集成氮化镓光电芯片的光响应调制，制备了一种宽压力传感范围、高灵敏度和多应用场景的的光电集成器件。第一作者为安小帅，通讯作者为褚智勤和李携曦。Chip是全球唯一聚焦芯片类研究的综合性国际期刊，是入选了国家高起点新刊计划的「三类高质量论文」期刊之一。

压力传感器在日常生活、医疗及工业领域中均有广泛应用，涉及医疗监测、诊断、人机交互以及水下运动追踪等多个方面2-5。当前报道的压力传感器主要基于压阻、电容、压电及摩擦发电和光学原理。其中，基于光学原理的压力传感器因其响应速度快、灵敏度高和抗电磁干扰等优势而备受关注6。然而，传统光学压力传感器需依赖外部光源与精密光学对准，这限制了其更广泛的应用。本研究探索将氮化镓基光源与光电探测器制备到同一微型器件上，并进一步结合聚二甲基硅氧烷（PDMS，polydimethylsiloxane）腔体与纳米光栅。通过检测光栅位移与形变导致的反射光强变化，实现压力传感功能，具体见图1a-1c。此外，本研究还将光电器件与电学模块相融合，如图1d所示，使采集到的压力信号能够实时显示在移动设备上，进而实现远程无线监测的功能。研究还展示了该技术在监测水下运动与心率方面的应用实例。

图1 | 光电器件和无线系统的概念和结构。a，具有无线监控功能的光电传感系统示意图。b，氮化镓芯片的光学图像。比例尺为1毫米。插图为工作状态下的氮化镓芯片。c，光电器件的光学图像。比例尺为3 mm。插图为DVD光栅的AFM图像。d，无线监控系统组件的光学图像。

图2a-2e表明，制备的光电器件具有-100 kPa~30.5 kPa的宽压力响应范围，且在多种压力响应模式下展现出高度的重复性与稳定性。如图2i所示，经超1,2000次循环性测试，器件对压力的响应波形仍保持一致，展现出其卓越的耐用性。此外，该器件还具备响应速度快、传感分辨率高的特点。如图2j,k所示，它能够精确捕捉到0.03 mg糖粒撞击过程中产生的微小压力变化。得益于PDMS的疏水性，该器件可以空气和水下两种环境下工作。在水下工作时，其最大可探测水深约为3米，且水深监测分辨率达到0.3毫米（相当于2.97 Pa），满足了大多数日常生活需求（图3a-d）。由于器件的小型化设计与PDMS腔体的柔性特性，它能够与人体紧密贴合，从而具备采集多种生理信号的能力。图中展示了包括脚踝、腕部等多个部位的心率信号采集实例。另外，通过对比10 mA与10 μA发光二极管（LED，light-emitting diode）驱动电流下采集的脉搏信号，也验证了器件在25.2 μW的极低功耗下仍能正常工作（图3e,f）。如图3g-i所示，研究还进一步探索了器件在呼吸监测、握力传感以及肌肉压力传感等多种可穿戴应用领域的潜在用途。

图2 | 传感器压力响应表征结果。a，测试正压力响应的实验装置。b，光电流随正压而变化。c-d，加载瞬时和阶跃正压力时的动态光电流响应。e-h，负压测试设备与光电流响应。i-k，器件的耐久度，瞬态响应与最低检测限表征。

图3 | 器件在监测人类活动和生理信号时的性能表现。a，监测0至100厘米水位的光电流响应。b，在1 mm、3 mm和5 mm深度移动设备时的光电流反应。c，水深传感分辨率表征。d，吹水面时测量的光电流响应曲线。e，器件测试心率的示意图和光电流波形。f，LED在10 mA和10 μA偏置电流工作时采集的心率信号比较。g-i，检测口罩内呼吸、抓取物体以及弯曲手指引起压力的光电流响应。

尽管该光电器件已在多种环境中展现出不同的传感功能，但其实际应用仍受限于需连接多种电学设备，特别是在水下环境中的压力传感方面。为此，本研究将光电集成器件与多种电学模块融合，制备出一套无线监测系统。该系统将光电器件采集的信号经电流-电压转换、滤波以及数模转换处理，并利用Arduino将信号发送至蓝牙设备。信号经过无线传输与接收后，在移动设备界面上实现了远程实时无线监测，具体流程如图4a所示。此外，该系统能通过感知水深变化引起的压力差异，远程监测人类在水下的各种运动。如图4b所示，系统能够准确监测并展示多种运动模式，包括大幅度、小幅度的上升与下落，以及台阶式的下落与上升等。运动过程中对应的水深变化数据能够实时在手机端呈现，为儿童游泳远程监测、溺水风险预防等领域提供了潜在的应用价值。如图4c，当将器件对准动脉位置时，该系统还能远程采集水下的脉搏信号，所采集到的心率波形包含了丰富的生理信息，如峰值强度（P、T和D）、收缩与舒张的持续时间以及心率等。

图4 | 水下无线监测人体运动和心跳。a， 无线监控系统设计示意图。b-c，实时监测水下人体运动和心率的照片和手机app接收数据。

Aversatile optoelectronic device for ultrasensitive negative-positive pressure sensing¹

Pressure sensors have a wide range of applications in daily life, medical and industrial fields, involving medical monitoring, diagnostics, human-machine interfaces, and underwater motion tracking2-5. Currently reported pressure sensors are mainly based on piezoresistive, capacitive, piezoelectric, triboelectric and optical principles. Among them, pressure sensors based on optical principles have drawn considerable attention due to their advantages of fast response speed, high sensitivity, and resistance to electromagnetic interference6. However, traditional optical pressure sensors need to rely on an external light source with precision optical alignment, limiting their wide applications. This study explores the preparation of a GaN-based light source and photodetector onto the same microdevice and combines a polydimethylsiloxane (PDMS) cavity with a nano grating. The pressure sensing function is realized by detecting the change in reflected light intensity due to grating displacement and deformation, as shown in Fig. 1a-c. In addition, this study also integrates the photodetector with an electrical module, as shown in Fig. 1d, so that the collected pressure signals can be displayed in real-time on a mobile device, which in turn realizes the function of remote wireless monitoring. The study also demonstrates an example of the application of this technology in monitoring underwater motion and heart rate.

Fig. 1 | Concept and structure of the proposed optoelectronic device and wireless system. a, Schematic diagram of the proposed optoelectronic device with wireless monitoring system. b, Optical image of the GaN chip. The scale bar is 1 mm. Inset shows the GaN chip under operation. c, Optical image of the optoelectronic device. The scale bar is 3 mm. Inset is the AFM image showing the surface morphology of the DVD grating. d, Optical image showing the components of the wireless monitoring system.

Fig. 2a-e show that the fabricated optoelectronic devices have a wide pressure response range from -100 kPa to 30.5 kPa, and exhibit a high degree of repeatability and stability in multiple pressure response modes. As shown in Fig. 2i, after more than 1,2000 cycles of cyclic testing, the device still maintains the same pressure response waveform, demonstrating its excellent durability. In addition, the device features fast response time and high sensing resolution. As shown in Fig. 2j, k, it is able to accurately capture the small pressure changes generated during the impact of a 0.03 mg sugar particle. Owing to the hydrophobicity of PDMS, the device can operate in both air and underwater environments. When operating underwater, it has a maximum detectable water depth of about 3 meters and a bathymetric monitoring resolution of 0.3 mm (equivalent to 2.97 Pa), which meets most daily life requirements (Fig. 3a-d). Due to the miniaturized design of the device and the flexible nature of the PDMS cavity, it is able to fit closely to the human body and thus can acquire a wide range of physiological signals. Examples of heart rate signal acquisition in various parts of the body, including the ankle and wrist, are shown in the figure. In addition, by comparing the pulse signals acquired under 10 mA and 10 μA light-emitting diode (LED) driving currents, it is also verified that the device can still work properly under the very low power consumption of 25.2 μW (Fig. 3e, f). As shown in Fig. 3g-i, the study further explores the potential use of the device in various wearable applications, such as respiration monitoring, grip force sensing, and muscle pressure sensing.

Fig. 2 | Characterizations when loading and unloading pressures on the sensor. a, Experimental setup for testing the response of the device to positive pressures. b, Photocurrent changes as a function of positive pressure. Dynamic photocurrent responses when loading c instantaneous and d stepwise positive pressure changes. e-h, Photocurrent responses when applying negative pressure for testing the dynamic performance corresponding to a-d. i, Cyclic measurement when pressure changes from 16.9 kPa to 30.1 kPa. j, Transient response of the device. k, Photocurrent changes when dropping a 0.3-mg sugar particle on the device. The inset shows optical images captured during the particle fall.

Fig. 3 | Performance of the optoelectronic when monitoring human activity and physiological signals. a, Photocurrent response for monitoring water level ranging from 0 to 100 cm. b, Photocurrent response when periodically moving the device in depths of 1 mm, 3 mm, and 5 mm. c, Characterizations for measuring resolution of water level when operating underwater. d, Measured photocurrent response curve when blowing the water surface. e, Schematic diagram and photocurrent waveforms collected from different artery positions by the device. f, Comparison when LED biased at 10 mA and 10 μA. g-i, Photocurrent changes when applying a device to detect the pressure changes induced by breathing in the mask, gripping force of holding a paper and a petri dish, and muscular pressure induced by bending fingers.

Although the optoelectronic device has been demonstrated with different sensing functions in various environments, its practical application still needs to be improved by connecting several electrical devices, especially for pressure sensing in underwater environments. For this reason, in this study, a wireless monitoring system is prepared by combining the optoelectronic integrated device with various electrical modules. The system processes the signals collected by the optoelectronic devices through current-voltage conversion, filtering, and digital-to-analog conversion, and sends the signals to a Bluetooth device using an Arduino. After the signal is transmitted and received wirelessly, remote real-time wireless monitoring is achieved on the mobile device interface, and the specific process is shown in Fig. 4a. In addition, the system is able to remotely monitor various human movements underwater by sensing the pressure difference caused by changes in water depth. As shown in Fig. 4b, the system is able to accurately monitor and display a variety of movement patterns, including large-amplitude and small-amplitude ascending and descending, as well as stepwise descending and ascending. The corresponding water depth change data during the movement can be presented in real-time on the mobile phone, which provides potential application value in areas such as remote monitoring of children's swimming and drowning risk prevention. As shown in Fig. 4c, the system is also capable of remotely capturing underwater pulse signals when the device is aimed at an arterial location, and the captured heart rate waveforms contain a wealth of physiological information, such as peak intensities (P, T, and D), systolic and diastolic durations, and heart rate.

Fig. 4 | Wirelessly monitoring the human movement and heart pulse underwater. a, Schematic diagram showing the design of the wireless monitoring system. b-c, Photograph and received data when real-time monitoring human movement and heart pulse underwater.

参考文献

1. An, X., Gui, S., Li, Y., Chu, Z. & Li, K. H. A versatile optoelectronic device for ultrasensitive negative-positive pressure sensing applications. Chip3, 100116 (2024).

2. Farooq, M. et al. Thin-film flexible wireless pressure sensor for continuous pressure monitoring in medical applications. Sensors20, 6653 (2020).

3. Lu, L. et al. Flexible Noncontact Sensing for Human-Machine Interaction. Adv. Mater.33, e2100218 (2021).

4. Ni, Y. et al. Robust superhydrophobic rGO/PPy/PDMS coatings on a polyurethane sponge for underwater pressure and temperature sensing. ACS Appl. Mater. Interfaces13, 53271-53281 (2021).

5. Zhou, X. et al. Gel-based strain/pressure sensors for underwater sensing: Sensing mechanisms, design strategies and applications. (in English), Compos. Part B-Eng.255, 110631 (2023).

6. Meng, K. et al. Wearable pressure sensors for pulse wave monitoring. Adv. Mater.34, e2109357 (2022).

论文链接：

作者简介

安小帅， 硕士毕业于哈尔滨工业大学（深圳）。目前攻读南方科技大学和香港大学联合项目博士学位。他的研究兴趣包括单片集成氮化镓基光电芯片、可穿戴电子产品和微流控。

Xiaoshuai An received his M.S. degree from the Harbin Institute of Technology, Shenzhen. He is currently a joint Ph.D. student at the Southern University of Science and Technology and the University of Hong Kong. His research interests include GaN-based monolithic photonic chips, wearable electronics, and microfluidics.

桂思哲， 硕士毕业于南方科技大学。他的研究兴趣为氮化镓光电传感芯片。

Sizhe Gui received his M.S. degree from the Southern University of Science and Technology. His research interests are in GaN optoelectronic sensors.

李颖欣，本科毕业于四川大学，目前正在南方科技大学攻读硕士学位。她的研究兴趣包括氮化镓基光电器件。

Yingxin Li received her B.S. degree from the Sichuan University, Sichuan, China. She is currently pursuing an M.S. degree at the Southern University of Science and Technology. Her research interests include GaN-based optoelectronic devices.

褚智勤，香港大学电气与电子工程系助理教授（与生物医学学院联合聘请），研究方向包括量子传感、生物物理学、生物光子学和材料生物学接口。

Zhiqin Chu is currently an Assistant Professor in the Department of Electrical and Electronic Engineering (Joint Appointment with the School of Biomedical Sciences) at the University of Hong Kong. His current research interests include quantum sensing, biophysics, biophotonics, and materials-biology interface.

李携曦，南方科技大学深港微电子学院助理教授，研究方向包括III族氮化物光电器件的设计、制造和表征。

Kwai Hei Li is currently working as an assistant professor in the School of Microelectronics at the Southern University of Science and Technology. His current research interests include the design, fabrication, and characterization of III-nitride optoelectronic devices.

关于Chip

Chip（ISSN：2772-2724，CN：31-2189/O4）是全球唯一聚焦芯片类研究的综合性国际期刊，已入选由中国科协、教育部、科技部、中科院等单位联合实施的「中国科技期刊卓越行动计划高起点新刊项目」、「中国科技期刊卓越行动计划二期项目-英文梯队期刊」，为科技部鼓励发表「三类高质量论文」期刊之一。

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Chip秉承创刊理念: All About Chip，聚焦芯片，兼容并包，旨在发表与芯片相关的各科研领域尖端突破性成果，助力未来芯片科技发展。迄今为止，Chip已在其编委会汇集了来自14个国家的69名世界知名专家学者，其中包括多名中外院士及IEEE、ACM、Optica等知名国际学会终身会士（Fellow）。

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来源：Future远见