https://scholar.dgist.ac.kr/handle/20.500.11750/47659 2026-10-03T23:47:28Z 2026-10-03T23:47:28Z Kumar, Naveen Kaja, Kushal Ruthvik Panda Swati Hajra Sugato Belal, Mohamed Ahmed Bhosale, Premkumar Sharad Khanapuram, Uday Kumar Rajaboina, Rakesh Kumar Keum, Hohyun Lee, Kyoungtae Kim, Hoe Joon https://scholar.dgist.ac.kr/handle/20.500.11750/60870 2026-09-23T06:40:16Z 2026-05-31T15:00:00Z

Title: Self-poled and poling-free efficient piezoelectric nanogenerators for power generation and self-powered applications Author(s): Kumar, Naveen; Kaja, Kushal Ruthvik; Panda Swati; Hajra Sugato; Belal, Mohamed Ahmed; Bhosale, Premkumar Sharad; Khanapuram, Uday Kumar; Rajaboina, Rakesh Kumar; Keum, Hohyun; Lee, Kyoungtae; Kim, Hoe Joon Abstract: Piezoelectric nanogenerators (PENGs) have emerged as promising energy harvesters capable of converting waste mechanical energy into usable electrical power for self-powered electronic applications. Traditionally, PENGs require an external poling process to align ferroelectric dipoles and achieve efficient operation. However, reliance on high-voltage poling, time-consuming processing, and potential material degradation limits the scalability and practicality of conventional PENGs. Recent research has therefore focused on developing self-poled, polingfree PENGs that offer intrinsic polarization, enhanced stability, and simplified fabrication without external treatments. This review summarizes the fundamental working principles of PENGs and the effect of polarization on their performance. Then, an in-depth discussion of the concept and comparison between the self-poling and poling-free mechanisms is provided. Recent advances in self-poled or poling-free PENGs, material innovations, including polymers, ceramics, and composites, as well as device engineering strategies that enable efficient energy conversion without external poling, are also demonstrated. The review concludes with significant challenges, including material durability, large-scale fabrication, and integration into complex systems, as well as future research prospects for developing next-generation self-powered technology. By integrating current advances and highlighting key obstacles, the review attempts to offer valuable insights into the future development of efficient, scalable, and environmentally sustainable poling-free PENGs. To the best of our knowledge, this is the first comprehensive review of self-poled and poling-free PENGs, focusing on underlying mechanisms, material fabrication methods, and emerging applications.

2026-05-31T15:00:00Z Panda, Swati Hajra, Sugato Bhosale, Premkumar Sharad Belal, Mohamed Ahmed Kaja, Kushal Ruthvik Kim, Hoe Joon Lee, Kyoungtae https://scholar.dgist.ac.kr/handle/20.500.11750/59341 2026-02-03T07:40:11Z 2026-02-28T15:00:00Z

Title: Triboelectric energy harvesting from rice paper/PDMS under extreme humidity environments Author(s): Panda, Swati; Hajra, Sugato; Bhosale, Premkumar Sharad; Belal, Mohamed Ahmed; Kaja, Kushal Ruthvik; Kim, Hoe Joon; Lee, Kyoungtae Abstract: A flexible and eco-friendly triboelectric nanogenerator (TENG) based on rice paper (RP) and Polydimethylsiloxane (PDMS) was fabricated for efficient energy harvesting. The device produced a high output of 305 V, 2.6 μA current, and a charge of 29 nC. Various biomechanical energies from different body motions were harvested using the RP-PDMS TENG device. Typically, the TENG output depleted under extreme environmental conditions. Hence, the TENG device was packed using a waste polythene pouch, which enabled greater stability of electrical voltage under harsh humidity conditions (>85 % RH). This packed TENG shows great promise for self-powered wearable devices and environmentally robust energy harvesting applications.

2026-02-28T15:00:00Z Lee, Kyoungtae Lall, Rahul Maharbiz, Michel M. Anwar, Mekhail https://scholar.dgist.ac.kr/handle/20.500.11750/58302 2025-12-18T02:42:04Z 2025-03-31T15:00:00Z

Title: A 0.05 mm3 diode-based single charged-particle real-time radiation detector for electron radiotherapy Author(s): Lee, Kyoungtae; Lall, Rahul; Maharbiz, Michel M.; Anwar, Mekhail Abstract: Real-time radiation monitoring at the single-particle level is an unmet need for electron radiotherapy, especially for dose deposition to targets in motion or critical OARs. We have developed a first-in-class CMOS-based 0.05 mm3 single electron sensitive detector. The chiplet integrates all the requisite electronics. The functionality of the system is verified under 6 and 9 MeV clinical electron beams. Percentage depth vs. pulse-width curves for 6 and 9 MeV beams are measured and verified using Monte-Carlo simulations. The proposed system has the potential to enhance the electron radiotherapy quality and safety, providing real-time dosimetry from multiple sites simultaneously. © 2025 The Author(s)

2025-03-31T15:00:00Z Lall, Rahul Lee, Kyoungtae Cunha, Adam Abergel, Rebecca Seo, Youngho Niknejad, Ali M. Anwar, Mekhail https://scholar.dgist.ac.kr/handle/20.500.11750/58230 2025-07-25T04:10:52Z 2025-03-31T15:00:00Z

Title: Single-X-Ray Sensitive Energy-Binning Dosimeter for Closed-Loop Cancer External-Beam Radiotherapy Author(s): Lall, Rahul; Lee, Kyoungtae; Cunha, Adam; Abergel, Rebecca; Seo, Youngho; Niknejad, Ali M.; Anwar, Mekhail Abstract: X-ray radiation dose delivered during cancer external-beam radiotherapy (EBRT) is nonlinear with the biological effect imparted to cancer cells and neighboring healthy tissues. This oftentimes leads to insufficient damage to cancer cells and excessive damage to the surrounding healthy tissues, both increasing toxicity and the risk of cancer recurrence later in life for many patients. An understanding of X-ray energy deposition at the single-X-ray level is, therefore, necessary to improve the efficacy of cancer radiotherapy. Here, we present a single-X-ray sensitive, energy-binning integrated circuit (IC)-based dosimeter, fabricated in 180 nm CMOS technology, to enable closed-loop cancer radiotherapy for personalized patient treatment. We use small 3 x 3 mu m reverse-biased deep n-well (DNWELL) diodes designed at low capacitive nodes (C-diode), such that the miniscule charge deposition (Q(dep)) from single X-rays at these nodes generates a voltage signal large enough to be sensed (V-diode = Q(dep)/C-diode). In order to enable single-X-ray energy resolution without significant power and area, we implement an analog voltage supply (AVDDH) similar to log resistor grid to create a sensitivity gradient across the 76 x 55 pixel array. The IC-based dosimeter was tested under scenarios consistent with the treatment of shallow lesions (e.g., skin cancer, superficial tumors, intraoperative radiotherapy). The system is highly linear with radiation dose (10-250 cGy) and accurately tracks dose up to 2 cm deep in tissue for 50-, 70-, and 100-kV X-ray beams.

2025-03-31T15:00:00Z