A Miniature GaN Chip for Surface Roughness Measurement

In this paper, a new method for rotational angle and speed measurements is proposed by integrating a GaN optoelectronic chip with a stepped disc. The optoelectronic chip that integrates a light-emitting diode (LED) and a photodiode (PD) is fabricated by wafer-level microfabrication. The disc is designed with a spiral staircase shape, and has increasing thickness distribution along the circumferential direction. The sensing mechanism is that the optoelectronic chip measures angle-dependent intensity change of the light reflected off the stepped disc. Through a series of performance tests, the chip is highly sensitive to a continuous rotation from 0∘ to 360∘, and produces photocurrent to indicate the rotational angle and speed. A rotational speed up to 5000 rpm is measured with a relative error less than 1.27%. The developed sensing architecture provides an alternative solution for constructing a low-cost, miniaturized, and high-efficiency rotational angle and speed sensing system.

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PDMS-assisted GaN optical hardness sensors

Zhu,

He,

Zhan

et al. 2023

Opt. Lett.

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In this Letter, an optical hardness sensor is fabricated based on a GaN-based device combined with finger-shaped PDMS. The chip-scale 1 mm × 1 mm GaN-based device is monolithically integrated with a light emitter and receiver responsible for light emission and photodetection, respectively. The micropatterned PDMS layer can effectively convert the hardness information of the measured object into an optical change detected by the receiver. Verified by experiment measurements, the sensor exhibits a linear response in a hardness range of 1–84 HA, a sensitivity of 0.24 µA/HA, a fast response time of 1.2 ms, and a high degree of repeatability and stability. The optical sensor has the characteristics of tiny size, high compactness, inexpensive fabrication cost, wide measurement range, and high stability, making it suitable for hardness measurement in practical applications.

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A Miniature GaN Chip for Surface Roughness Measurement

Cited by 3 publications

References 30 publications

Fast Response PDMS/GaN Optical Vacuum Microsensors

Fast Response PDMS/GaN Optical Vacuum Microsensors

Rotational angle and speed detection via a chip-scale GaN optoelectronic device

PDMS-assisted GaN optical hardness sensors

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