@article{zhao_annayev_oralkan_jia_2022, title={An Ultrasonic Energy Harvesting IC Providing Adjustable Bias Voltage for Pre-Charged CMUT}, volume={16}, ISSN={["1940-9990"]}, url={https://doi.org/10.1109/TBCAS.2022.3178581}, DOI={10.1109/TBCAS.2022.3178581}, abstractNote={Ultrasonic wireless power transmission (WPT) using pre-charged capacitive micromachined ultrasonic transducers (CMUT) is drawing great attention due to the easy integration of CMUT with CMOS techniques. Here, we present an integrated circuit (IC) that interfaces with a pre-charged CMUT device for ultrasonic energy harvesting. We implemented an adaptive high voltage charge pump (HVCP) in the proposed IC, which features low power, overvoltage stress (OVS) robustness, and a wide output range. The ultrasonic energy harvesting IC is fabricated in the 180 nm HV BCD process and occupies a 2 × 2.5 mm2 silicon area. The adaptive HVCP offers a 2× – 12× voltage conversion ratio (VCR), thereby providing a wide bias voltage range of 4 V–44 V for the pre-charged CMUT. Moreover, a VCR tunning finite state machine (FSM) implemented in the proposed IC can dynamically adjust the VCR to stabilize the HVCP output (i.e., the pre-charged CMUT bias voltage) to a target voltage in a closed-loop manner. Such a closed-loop control mechanism improves the tolerance of the proposed IC to the received power variation caused by misalignments, amount of transmitted power change, and/or load variation. Besides, the proposed ultrasonic energy harvesting IC has an average power consumption of 35 μW–554 μW corresponding to the HVCP output from 4 V–44 V. The CMUT device with a local surface acoustic intensity of 3.78 mW/mm2, which is well below the FDA limit for power flux (7.2 mW/mm2), can deliver sufficient power to the IC.}, number={5}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Zhao, Linran and Annayev, Muhammetgeldi and Oralkan, Omer and Jia, Yaoyao}, year={2022}, month={Oct}, pages={842–851} }
 @article{yang_gong_yao_shrestha_jia_qiu_fan_weber_li_2021, title={A fully transparent, flexible PEDOT:PSS-ITO-Ag-ITO based microelectrode array for ECoG recording}, volume={21}, ISSN={["1473-0189"]}, DOI={10.1039/d0lc01123a}, abstractNote={Ultra-flexible, highly-conductive and fully-transparent μECoG electrode arrays made of PEDOT:PSS–ITO–Ag–ITO on thin parylene C successfully achieved neurophysiology recording.}, number={6}, journal={LAB ON A CHIP}, author={Yang, Weiyang and Gong, Yan and Yao, Cheng-You and Shrestha, Maheshwar and Jia, Yaoyao and Qiu, Zhen and Fan, Qi Hua and Weber, Arthur and Li, Wen}, year={2021}, month={Mar}, pages={1096–1108} }
 @article{li_mills_flewwellin_herzberg_bosari_lim_jia_jur_2021, title={Influence of Armband Form Factors on Wearable ECG Monitoring Performance}, volume={21}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2021.3059997}, abstractNote={In the current state of innovation in wearable technology, there is a vast array of biomonitoring devices available to record electrocardiogram (ECG) in users, a key indicator of cardiovascular health. Of these devices, armband form factors serve as a convenient all-in-one platform for integration of electronic systems; yet, much of the current literature does not address the appropriate electrode location nor contact pressures necessary to achieve reliable system level ECG sensing. Therefore, this paper will elucidate the role of electrode location and contact pressure on the ECG sensing performance of an electronic textile (E-textile) armband worn on the upper left arm. We first carry out an ECG signal characterization to validate the ideal armband electrode placement necessary to measure high quality signals without sacrificing practical assembly of the armband. We then model and experimentally quantify the contact pressure between the armband onto the upper arm as a function of armband size, a critical parameter dictating skin-electrode impedance and ECG signal quality. Finally, we evaluate how the size of the armband form factor affects its ECG sensing performance. Our experimental results confirm that armbands exhibiting modeled contact pressures between 500 Pa to 1500 Pa can acquire ECG signals. However, armband sizes exhibiting experimental contact pressures of 1297 ± 102 Pa demonstrate the best performance with similar signal-to-noise ratios (SNR) compared to wet electrode benchmarks. The fundamental design parameters discussed in this work serve as a benchmark for the design of future E-textile and wearable form factors with efficient sensing performance.}, number={9}, journal={IEEE SENSORS JOURNAL}, author={Li, Braden M. and Mills, Amanda C. and Flewwellin, Tashana J. and Herzberg, Jacklyn L. and Bosari, Azin Saberi and Lim, Michael and Jia, Yaoyao and Jur, Jesse S.}, year={2021}, month={May}, pages={11046–11060} }
 @article{jia_lee_kong_zeng_connolly_mahmoudi_ghovanloo_2020, title={A Software-Defined Radio Receiver for Wireless Recording From Freely Behaving Animals (vol 13, pg 979, 2019)}, volume={14}, ISSN={["1940-9990"]}, DOI={10.1109/TBCAS.2020.2991644}, abstractNote={Presents corrections to author affiliation information in the above named paper.}, number={3}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Jia, Yaoyao and Lee, Byunghun and Kong, Fanpeng and Zeng, Zhaoping and Connolly, Mark and Mahmoudi, Babak and Ghovanloo, Maysam}, year={2020}, month={Jun}, pages={631–631} }
 @article{jia_guler_lai_gong_weber_li_ghovanloo_2020, title={A Trimodal Wireless Implantable Neural Interface System-on-Chip}, volume={14}, ISSN={["1940-9990"]}, DOI={10.1109/TBCAS.2020.3037452}, abstractNote={A wireless and battery-less trimodal neural interface system-on-chip (SoC), capable of 16-ch neural recording, 8-ch electrical stimulation, and 16-ch optical stimulation, all integrated on a 5 ×  3 mm2 chip fabricated in 0.35-μm standard CMOS process. The trimodal SoC is designed to be inductively powered and communicated. The downlink data telemetry utilizes on–off keying pulse-position modulation (OOK-PPM) of the power carrier to deliver configuration and control commands at 50 kbps. The analog front-end (AFE) provides adjustable mid-band gain of 55–70 dB, low/high cut-off frequencies of 1–100 Hz/10 kHz, and input-referred noise of 3.46 μVrms within 1 Hz-50 kHz band. AFE outputs of every two-channel are digitized by a 50 kS/s 10-bit SAR-ADC, and multiplexed together to form a 6.78 Mbps data stream to be sent out by OOK modulating a 434 MHz RF carrier through a power amplifier (PA) and 6 cm monopole antenna, which form the uplink data telemetry. Optical stimulation has a switched-capacitor based stimulation (SCS) architecture, which can sequentially charge four storage capacitor banks up to 4 V and discharge them in selected μLEDs at instantaneous current levels of up to 24.8 mA on demand. Electrical stimulation is supported by four independently driven stimulating sites at 5-bit controllable current levels in ±(25–775) μA range, while active/passive charge balancing circuits ensure safety. In vivo testing was conducted on four anesthetized rats to verify the functionality of the trimodal SoC.}, number={6}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Jia, Yaoyao and Guler, Ulkuhan and Lai, Yen-Pang and Gong, Yan and Weber, Arthur and Li, Wen and Ghovanloo, Maysam}, year={2020}, month={Dec}, pages={1207–1217} }
 @article{jia_gong_weber_li_ghovanloo_2020, title={A mm-Sized Free-Floating Wireless Implantable Opto-Electro Stimulation Device}, volume={11}, ISSN={["2072-666X"]}, DOI={10.3390/mi11060621}, abstractNote={Towards a distributed neural interface, consisting of multiple miniaturized implants, for interfacing with large-scale neuronal ensembles over large brain areas, this paper presents a mm-sized free-floating wirelessly-powered implantable opto-electro stimulation (FF-WIOS2) device equipped with 16-ch optical and 4-ch electrical stimulation for reconfigurable neuromodulation. The FF-WIOS2 is wirelessly powered and controlled through a 3-coil inductive link at 60 MHz. The FF-WIOS2 receives stimulation parameters via on-off keying (OOK) while sending its rectified voltage information to an external headstage for closed-loop power control (CLPC) via load-shift-keying (LSK). The FF-WIOS2 system-on-chip (SoC), fabricated in a 0.35-µm standard CMOS process, employs switched-capacitor-based stimulation (SCS) architecture to provide large instantaneous current needed for surpassing the optical stimulation threshold. The SCS charger charges an off-chip capacitor up to 5 V at 37% efficiency. At the onset of stimulation, the capacitor delivers charge with peak current in 1.7–12 mA range to a micro-LED (µLED) array for optical stimulation or 100–700 μA range to a micro-electrode array (MEA) for biphasic electrical stimulation. Active and passive charge balancing circuits are activated in electrical stimulation mode to ensure stimulation safety. In vivo experiments conducted on three anesthetized rats verified the efficacy of the two stimulation mechanisms. The proposed FF-WIOS2 is potentially a reconfigurable tool for performing untethered neuromodulation.}, number={6}, journal={MICROMACHINES}, author={Jia, Yaoyao and Gong, Yan and Weber, Arthur and Li, Wen and Ghovanloo, Maysam}, year={2020}, month={Jun} }
 @article{atef_hung_jia_lee_sahin_2020, title={Editorial: Special Issue on Selected Papers From ISICAS 2020 Guest Editors' Introduction}, volume={14}, ISSN={["1940-9990"]}, DOI={10.1109/TBCAS.2020.3026225}, abstractNote={The papers in this special section were presented at the 2020 International Symposium on Integrated Circuits and Systems (ISICAS) in a virtual conference that was held from August 27–28, 2020.}, number={5}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Atef, M. and Hung, C. -C. and Jia, Y. and Lee, S. -Y. and Sahin, M.}, year={2020}, month={Oct}, pages={930–930} }
 @article{mirbozorgi_jia_zhang_ghovanloo_2020, title={Toward a High-Throughput Wireless Smart Arena for Behavioral Experiments on Small Animals}, volume={67}, ISSN={["1558-2531"]}, DOI={10.1109/TBME.2019.2961297}, abstractNote={This work presents a high-throughput and scalable wirelessly-powered smart arena for behavioral experiments made of multiple EnerCage Homecage (HC) systems, operating in parallel in a way that they can fit in standard racks that are commonly used in animal facilities. The proposed system, which is referred to as the multi-EnerCage-HC (mEHC), increases the volume of data that can be collected from more animal subjects, while lowering the cost and duration of experiments as well as stress-induced bias by minimizing the involvement of human operators. Thus improving the quality, reproducibility, and statistical power of experiment outcomes, while saving precious lab space. The system is equipped with an auto-tuning mechanism to compensate for the resonance frequency shifts caused by the dynamic nature of the mutual inductance between adjacent homecages. A functional prototype of the mEHC system has been implemented with 7 units and analyzed for theoretical design considerations that would minimize the effects of interference and resonance frequency bifurcation. Experiment results demonstrate robust wireless power and data transmissions capabilities of this system within the noisy lab environment.}, number={8}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Mirbozorgi, S. Abdollah and Jia, Yaoyao and Zhang, Pengcheng and Ghovanloo, Maysam}, year={2020}, pages={2359–2369} }
 @misc{lee_jia_2020, title={Wirelessly-Powered Cage Designs for Supporting Long-Term Experiments on Small Freely Behaving Animals in a Large Experimental Arena}, volume={9}, ISSN={["2079-9292"]}, DOI={10.3390/electronics9121999}, abstractNote={In modern implantable medical devices (IMDs), wireless power transmission (WPT) between inside and outside of the animal body is essential to power the IMD. Unlike conventional WPT, which transmits the wireless power only between fixed Tx and Rx coils, the wirelessly-powered cage system can wirelessly power the IMD implanted in a small animal subject while the animal freely moves inside the cage during the experiment. A few wirelessly-powered cage systems have been developed to either directly power the IMD or recharge batteries during the experiment. Since these systems adapted different power carrier frequencies, coil configurations, subject tracking techniques, and wireless powered area, it is important for designers to select suitable wirelessly-powered cage designs, considering the practical limitations in wirelessly powering the IMD, such as power transfer efficiency (PTE), power delivered to load (PDL), closed-loop power control (CLPC), scalability, spatial/angular misalignment, near-field data telemetry, and safety issues against various perturbations during the longitudinal animal experiment. In this article, we review the trend of state-of-the-art wirelessly-powered cage designs and practical considerations of relevant technologies for various IMD applications.}, number={12}, journal={ELECTRONICS}, author={Lee, Byunghun and Jia, Yaoyao}, year={2020}, month={Dec} }
 @article{jia_lee_kong_zeng_connolly_mahmoudi_ghovanloo_2019, title={A Software-Defined Radio Receiver for Wireless Recording From Freely Behaving Animals}, volume={13}, ISSN={["1940-9990"]}, DOI={10.1109/TBCAS.2019.2949233}, abstractNote={To eliminate tethering effects on the small animals’ behavior during electrophysiology experiments, such as neural interfacing, a robust and wideband wireless data link is needed for communicating with the implanted sensing elements without blind spots. We present a software-defined radio (SDR) based scalable data acquisition system, which can be programmed to provide coverage over standard-sized or customized experimental arenas. The incoming RF signal with the highest power among SDRs is selected in real-time to prevent data loss in the presence of spatial and angular misalignments between the transmitter (Tx) and receiver (Rx) antennas. A 32-channel wireless neural recording system-on-a-chip (SoC), known as WINeRS-8, is embedded in a headstage and transmits digitalized raw neural signals, which are sampled at 25 kHz/ch, at 9 Mbps via on-off keying (OOK) of a 434 MHz RF carrier. Measurement results show that the dual-SDR Rx system reduces the packet loss down to 0.12%, on average, by eliminating the blind spots caused by the moving Tx directionality. The system operation is verified in vivo on a freely behaving rat and compared with a commercial hardwired system.}, number={6}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Jia, Yaoyao and Lee, Byunghun and Kong, Fanpeng and Zeng, Zhaoping and Connolly, Mark and Mahmoudi, Babak and Ghovanloo, Maysam}, year={2019}, month={Dec}, pages={1645–1654} }