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1. Ultrasonic vibration-assisted scribing of sapphire: effects of ultrasonic vibration and tool geometry

   https://doi.org/10.1007/s00170-025-15071-3  

   Ansary, Shah_Rumman; Kabir, Sarower; Nnokwe, Cynthia; He, Rui; Cong, Weilong (January 2025, The International Journal of Advanced Manufacturing Technology)

   Abstract In recent years, semiconductors, electronics, optics, and various other industries have seen a significant surge in the use of sapphire materials, driven by their exceptional mechanical and chemical properties. The machining of sapphire surfaces plays a crucial role in all these applications. However, due to sapphires’ exceptionally high hardness (Mohs hardness of 9, Vickers hardness of 2300) and brittleness, machining them often presents challenges such as microcracking and chipping of the workpiece, as well as significant tool wear, making sapphires difficult to cut. To enhance the machining efficiency and machined surface integrity, ultrasonic vibration-assisted (UV-A) machining of sapphire has already been studied, showing improved performance with lower cutting force, better surface finish, and extended tool life. Scribing tests using a single-diamond tool not only are an effective method to understand the material removal mechanism and deformation characteristics during such UV-A machining processes but also can be used as a potential process for separating IC chips from wafers. This paper presents a comprehensive study of the UV-A scribing process, aiming to develop an understanding of sapphire’s material removal mechanism under varying ultrasonic power levels and cutting tool geometries. In this experimental investigation, the effect of five different levels of ultrasonic power and three different cutting tool tip angles at various feeding depths on the scribe-induced features of the sapphire surface has been presented with a quantitative and qualitative comparison. The findings indicate that at feeding depths less than 6 μm, UV-A scribing with 40–80% ultrasonic power can reduce cutting force up to 50% and thus improve scribe quality. However, between feeding depths of 6 to 10 μm, this advantage of using ultrasonic vibration gradually diminishes. Additionally, UV-A scribing with a smaller tool tip angle (60°) was found to lower cutting force by 65% and improve scribe quality, effectively inhibiting residual stress formation and microcrack propagation. Furthermore, UV-A scribing also facilitated higher critical feeding depths at around 10 μm, compared to 6 μm in conventional scribing. 

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2. Rotary Ultrasonic Micro-grooving of Silicon: Effects of Ultrasonic Vibration and Feeding Speed

   https://doi.org/10.1016/j.mfglet.2025.06.084  

   Ansary, Shah Rumman; Kabir, Sarower; Lalith, Nithin; Zhang, Meng; Cong, Weilong (June 2025, ELSEVIER)
3. Rotary ultrasonic surface machining of silicon: Effects of ultrasonic power and tool rotational speed

   https://doi.org/10.1016/j.mfglet.2024.09.063  

   Kabir, Sarower; Ansary, Shah Rumman; Li, Yunze; Zhang, Meng; Cong, Weilong (October 2024, Manufacturing Letters)
4. Ultrasonic Microplotting of Microgel Bioinks

   https://doi.org/10.1021/acsami.0c15056  

   Chester, D.; Theetharappan, P.; Ngobili, T.; Daniele, M.; Brown, A. C. (October 2020, ACS Applied Materials & Interfaces)

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5. Ultrasonic Hydrogel Biochemical Sensor System

   https://doi.org/10.1109/EMBC44109.2020.9176216  

   Byun, Eunjeong; Nam, Juhong; Shim, Hyunji; Kim, Esther; Kim, Albert; Song, Seunghyun (July 2020, 2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC))

   In this work, we present a proof-of-concept hydrogel-based sensor system capable of wireless biochemical sensing through measuring backscattered ultrasound. The system consists of silica-nanoparticle embedded hydrogel deposited on a thin glass substrate, presenting two interfaces for backscattering (tissue/hydrogel and hydrogel/glass), which allows for system output to be invariant under the change in acoustic properties (e.g. attenuation, reflection) of the intervening biological tissue. We characterize the effect of silica nanoparticles (acoustic contrast agents) loading on the hydrogel's swelling ratio and its ultrasonic backscattering properties. We demonstrate a wireless pH measurement using dual modes of interrogations, reflection ratio and time delay. The ultrasonic hydrogel pH sensor is demonstrated with a sensing resolution of 0.2 pH level change with a wireless sensing distance around 10 cm. 

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