Xiangjun Chen

All Publications

• A noise-tolerant human–machine interface based on deep learning-enhanced wearable sensors Nature Sensors Chen, X., Lou, Z., Gao, X., Yin, L., Qin, S., Lin, M., Zhang, F., Lu, Y., Ding, S., Liu, R., Tang, S., Zhou, S., Dang, D. T., Yang, X., Wu, Z., Zhang, Z., Hu, H., Wang, X., Zhu, Y., Xu, Y., Sheng, R., Zhou, J., Lu, C., Wang, R., Yue, W., et al 2026; 1 (1): 39-41

  View details for DOI 10.1038/s44460-025-00001-3

• A single-transducer echomyography system for monitoring muscle activity NATURE ELECTRONICS Chen, X., Gao, X. 2024; 7 (11): 944-945

  View details for DOI 10.1038/s41928-024-01273-2

  View details for Web of Science ID 001347883500001

• A wearable echomyography system based on a single transducer. Nature electronics Gao, X., Chen, X., Lin, M., Yue, W., Hu, H., Qin, S., Zhang, F., Lou, Z., Yin, L., Huang, H., Zhou, S., Bian, Y., Yang, X., Zhu, Y., Mu, J., Wang, X., Park, G., Lu, C., Wang, R., Wu, R. S., Wang, J., Li, J., Xu, S. 2024; 7 (11): 1035-1046

  Abstract

  Wearable electromyography devices can detect muscular activity for health monitoring and body motion tracking, but this approach is limited by weak and stochastic signals with a low spatial resolution. Alternatively, echomyography can detect muscle movement using ultrasound waves, but typically relies on complex transducer arrays, which are bulky, have high power consumption and can limit user mobility. Here we report a fully integrated wearable echomyography system that consists of a customized single transducer, a wireless circuit for data processing and an on-board battery for power. The system can be attached to the skin and provides accurate long-term wireless monitoring of muscles. To illustrate its capabilities, we use this system to detect the activity of the diaphragm, which allows the recognition of different breathing modes. We also develop a deep learning algorithm to correlate the single-transducer radio-frequency data from forearm muscles with hand gestures to accurately and continuously track 13 hand joints with a mean error of only 7.9°.

  View details for DOI 10.1038/s41928-024-01271-4

  View details for PubMedID 40677283

  View details for PubMedCentralID PMC12269893

• A photoacoustic patch for three-dimensional imaging of hemoglobin and core temperature. Nature communications Gao, X., Chen, X., Hu, H., Wang, X., Yue, W., Mu, J., Lou, Z., Zhang, R., Shi, K., Chen, X., Lin, M., Qi, B., Zhou, S., Lu, C., Gu, Y., Yang, X., Ding, H., Zhu, Y., Huang, H., Ma, Y., Li, M., Mishra, A., Wang, J., Xu, S. 2022; 13 (1): 7757

  Abstract

  Electronic patches, based on various mechanisms, allow continuous and noninvasive monitoring of biomolecules on the skin surface. However, to date, such devices are unable to sense biomolecules in deep tissues, which have a stronger and faster correlation with the human physiological status than those on the skin surface. Here, we demonstrate a photoacoustic patch for three-dimensional (3D) mapping of hemoglobin in deep tissues. This photoacoustic patch integrates an array of ultrasonic transducers and vertical-cavity surface-emitting laser (VCSEL) diodes on a common soft substrate. The high-power VCSEL diodes can generate laser pulses that penetrate >2 cm into biological tissues and activate hemoglobin molecules to generate acoustic waves, which can be collected by the transducers for 3D imaging of the hemoglobin with a high spatial resolution. Additionally, the photoacoustic signal amplitude and temperature have a linear relationship, which allows 3D mapping of core temperatures with high accuracy and fast response. With access to biomolecules in deep tissues, this technology adds unprecedented capabilities to wearable electronics and thus holds significant implications for various applications in both basic research and clinical practice.

  View details for DOI 10.1038/s41467-022-35455-3

  View details for PubMedID 36522334

  View details for PubMedCentralID PMC9755152

• Fabric-substrated capacitive biopotential sensors enhanced by dielectric nanoparticles NANO RESEARCH Chen, X., Gao, X., Nomoto, A., Shi, K., Lin, M., Hu, H., Gu, Y., Zhu, Y., Wu, Z., Chen, X., Wang, X., Qi, B., Zhou, S., Ding, H., Xu, S. 2021; 14 (9): 3248-3252

  View details for DOI 10.1007/s12274-021-3458-0

  View details for Web of Science ID 000640147500003

• Clinical validation of a wearable ultrasound sensor of blood pressure. Nature biomedical engineering Zhou, S., Park, G., Longardner, K., Lin, M., Qi, B., Yang, X., Gao, X., Huang, H., Chen, X., Bian, Y., Hu, H., Wu, R. S., Yue, W., Li, M., Lu, C., Wang, R., Qin, S., Tasali, E., Karrison, T., Thomas, I., Smarr, B., Kistler, E. B., Khiami, B. A., Litvan, I., Xu, S. 2025; 9 (6): 865-881

  Abstract

  Options for the continuous and non-invasive monitoring of blood pressure are limited. Cuff-based sphygmomanometers are widely available, yet provide only discrete measurements. The clinical gold-standard approach for the continuous monitoring of blood pressure requires an arterial line, which is too invasive for routine use. Wearable ultrasound for the continuous and non-invasive monitoring of blood pressure promises to elevate the quality of patient care, yet the isolated sonographic windows in the most advanced prototypes can lead to inaccurate or error-prone measurements, and the safety and performance of these devices have not been thoroughly evaluated. Here we describe validation studies, conducted during daily activities at home, in the outpatient clinic, in the cardiac catheterization laboratory and in the intensive care unit, of the safety and performance of a wearable ultrasound sensor for blood pressure monitoring. The sensor has closely connected sonographic windows and a backing layer that improves the sensor's accuracy and reliability to meet the highest requirements of clinical standards. The validation results support the clinical use of the sensor.

  View details for DOI 10.1038/s41551-024-01279-3

  View details for PubMedID 39567702

  View details for PubMedCentralID 137445

• A fingertip-wearable microgrid system for autonomous energy management and metabolic monitoring NATURE ELECTRONICS Ding, S., Saha, T., Yin, L., Liu, R., Khan, M., Chang, A., Lee, H., Zhao, H., Liu, Y., Nazemi, A., Zhou, J., Chen, C., Li, Z., Zhang, C., Earney, S., Tang, S., Djassemi, O., Chen, X., Lin, M., Sandhu, S. S., Moon, J., Moonla, C., Nandhakumar, P., Park, Y., Mahato, K., Xu, S., Wang, J. 2024; 7 (9)

  View details for DOI 10.1038/s41928-024-01236-7

  View details for Web of Science ID 001303741500001

• Highly Recyclable and Tough Elastic Vitrimers from a Defined Polydimethylsiloxane Network. Angewandte Chemie (International ed. in English) Luo, J., Zhao, X., Ju, H., Chen, X., Zhao, S., Demchuk, Z., Li, B., Bocharova, V., Carrillo, J. Y., Keum, J. K., Xu, S., Sokolov, A. P., Chen, J., Cao, P. F. 2023; 62 (47): e202310989

  Abstract

  Despite intensive research on sustainable elastomers, achieving elastic vitrimers with significantly improved mechanical properties and recyclability remains a scientific challenge. Herein, inspired by the classical elasticity theory, we present a design principle for ultra-tough and highly recyclable elastic vitrimers with a defined network constructed by chemically crosslinking the pre-synthesized disulfide-containing polydimethylsiloxane (PDMS) chains with tetra-arm polyethylene glycol (PEG). The defined network is achieved by the reduced dangling short chains and the relatively uniform molecular weight of network strands. Such elastic vitrimers with the defined network, i.e., PDMS-disulfide-D, exhibit significantly improved mechanical performance than random analogous, previously reported PDMS vitrimers, and even commercial silicone-based thermosets. Moreover, unlike the vitrimers with random network that show obvious loss in mechanical properties after recycling, those with the defined network enable excellent thermal recyclability. The PDMS-disulfide-D also deliver comparable electrochemical signals if utilized as substrates for electromyography sensors after the recycling. The multiple relaxation processes are revealed via a unique physical approach. Multiple techniques are also applied to unravel the microscopic mechanism of the excellent mechanical performance and recyclability of such defined network.

  View details for DOI 10.1002/anie.202310989

  View details for PubMedID 37783669

• Stretchable ultrasonic arrays for the three-dimensional mapping of the modulus of deep tissue. Nature biomedical engineering Hu, H., Ma, Y., Gao, X., Song, D., Li, M., Huang, H., Qian, X., Wu, R., Shi, K., Ding, H., Lin, M., Chen, X., Zhao, W., Qi, B., Zhou, S., Chen, R., Gu, Y., Chen, Y., Lei, Y., Wang, C., Wang, C., Tong, Y., Cui, H., Abdal, A., Zhu, Y., Tian, X., Chen, Z., Lu, C., Yang, X., Mu, J., Lou, Z., Eghtedari, M., Zhou, Q., Oberai, A., Xu, S. 2023; 7 (10): 1321-1334

  Abstract

  Serial assessment of the biomechanical properties of tissues can be used to aid the early detection and management of pathophysiological conditions, to track the evolution of lesions and to evaluate the progress of rehabilitation. However, current methods are invasive, can be used only for short-term measurements, or have insufficient penetration depth or spatial resolution. Here we describe a stretchable ultrasonic array for performing serial non-invasive elastographic measurements of tissues up to 4 cm beneath the skin at a spatial resolution of 0.5 mm. The array conforms to human skin and acoustically couples with it, allowing for accurate elastographic imaging, which we validated via magnetic resonance elastography. We used the device to map three-dimensional distributions of the Young's modulus of tissues ex vivo, to detect microstructural damage in the muscles of volunteers before the onset of soreness and to monitor the dynamic recovery process of muscle injuries during physiotherapies. The technology may facilitate the diagnosis and treatment of diseases affecting tissue biomechanics.

  View details for DOI 10.1038/s41551-023-01038-w

  View details for PubMedID 37127710

  View details for PubMedCentralID 6636265

• A fully integrated wearable ultrasound system to monitor deep tissues in moving subjects. Nature biotechnology Lin, M., Zhang, Z., Gao, X., Bian, Y., Wu, R. S., Park, G., Lou, Z., Zhang, Z., Xu, X., Chen, X., Kang, A., Yang, X., Yue, W., Yin, L., Wang, C., Qi, B., Zhou, S., Hu, H., Huang, H., Li, M., Gu, Y., Mu, J., Yang, A., Yaghi, A., Chen, Y., Lei, Y., Lu, C., Wang, R., Wang, J., Xiang, S., Kistler, E. B., Vasconcelos, N., Xu, S. 2023

  Abstract

  Recent advances in wearable ultrasound technologies have demonstrated the potential for hands-free data acquisition, but technical barriers remain as these probes require wire connections, can lose track of moving targets and create data-interpretation challenges. Here we report a fully integrated autonomous wearable ultrasonic-system-on-patch (USoP). A miniaturized flexible control circuit is designed to interface with an ultrasound transducer array for signal pre-conditioning and wireless data communication. Machine learning is used to track moving tissue targets and assist the data interpretation. We demonstrate that the USoP allows continuous tracking of physiological signals from tissues as deep as 164mm. On mobile subjects, the USoP can continuously monitor physiological signals, including central blood pressure, heart rate and cardiac output, for as long as 12h. This result enables continuous autonomous surveillance of deep tissue signals toward the internet-of-medical-things.

  View details for DOI 10.1038/s41587-023-01800-0

  View details for PubMedID 37217752

• A wearable cardiac ultrasound imager. Nature Hu, H., Huang, H., Li, M., Gao, X., Yin, L., Qi, R., Wu, R. S., Chen, X., Ma, Y., Shi, K., Li, C., Maus, T. M., Huang, B., Lu, C., Lin, M., Zhou, S., Lou, Z., Gu, Y., Chen, Y., Lei, Y., Wang, X., Wang, R., Yue, W., Yang, X., Bian, Y., Mu, J., Park, G., Xiang, S., Cai, S., Corey, P. W., Wang, J., Xu, S. 2023; 613 (7945): 667-675

  Abstract

  Continuous imaging of cardiac functions is highly desirable for the assessment of long-term cardiovascular health, detection of acute cardiac dysfunction and clinical management of critically ill or surgical patients1-4. However, conventional non-invasive approaches to image the cardiac function cannot provide continuous measurements owing to device bulkiness5-11, and existing wearable cardiac devices can only capture signals on the skin12-16. Here we report a wearable ultrasonic device for continuous, real-time and direct cardiac function assessment. We introduce innovations in device design and material fabrication that improve the mechanical coupling between the device and human skin, allowing the left ventricle to be examined from different views during motion. We also develop a deep learning model that automatically extracts the left ventricular volume from the continuous image recording, yielding waveforms of key cardiac performance indices such as stroke volume, cardiac output and ejection fraction. This technology enables dynamic wearable monitoring of cardiac performance with substantially improved accuracy in various environments.

  View details for DOI 10.1038/s41586-022-05498-z

  View details for PubMedID 36697864

• Deciphering facial movements. Nature biomedical engineering Gao, X., Chen, X., Xu, S. 2020; 4 (10): 935-936

  View details for DOI 10.1038/s41551-020-00629-1

  View details for PubMedID 33093666