Sensors are core elements to directly obtain information from surrounding objects for further detecting, judging and controlling purposes. With the rapid development of soft electronics, flexible sensors have made considerable progress, and can better fit the objects to detect and, thus respond to changes more sensitively. Recently, as a newly emerging electronic ink, liquid metal is being increasingly investigated to realize various electronic elements, especially soft ones. Compared to conventional soft sensors, the introduction of liquid metal shows rather unique advantages. Due to excellent flexibility and conductivity, liquid-metal soft sensors present high enhancement in sensitivity and precision, thus producing many profound applications. So far, a series of flexible and wearable sensors based on liquid metal have been designed and tested. Their applications have also witnessed a growing exploration in biomedical areas, including health-monitoring, electronic skin, wearable devices and intelligent robots etc. This article presents a systematic review of the typical progress of liquid metal-enabled soft sensors, including material innovations, fabrication strategies, fundamental principles, representative application examples, and so on. The perspectives of liquid-metal soft sensors is finally interpreted to conclude the future challenges and opportunities.

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Advances in Liquid Metal-Enabled Flexible and Wearable Sensors.

Liquid metal enabled injectable biomedical technologies and applications

https://www.mdpi.com/2079-6374/10/11/170/pdf

Liquid Metal Based Flexible and Implantable Biosensors.

Liquid metals, highly conductive and flowable metals, are increasingly becoming versatile choices for soft electronics and wearable devices. High resolution liquid metal patterning strategies accommodative to different substrate materials and...

Intermetallic wetting enabled high resolution liquid metal patterning for 3D and flexible electronics

Liquid metal–enabled cybernetic electronics

Eye movement tracking is concerned with many important areas of research, of which tracking with a traditional scleral search coil system is deemed the gold standard. However, since such coil system requires anaesthetic use due to the stiffness of the copper wire coil in the system, it is of great importance to improve the wearing sensation experience. Here, an innovative electronic system for eye movement recording is proposed and realized, in which a liquid metal coil is introduced as the core element, attempting to provide a comfortable eye sensation. Theoretical investigation shows that this type of coil has performance similar to the traditional copper coil, which implies it is suitable for eye movement tracking. It has been demonstrated that such liquid metal coil is soft, flexible, and easy to produce, indicating that the coil is potentially favorable as a wearable medical device. Experiments show that the variance fitting curve between the induced voltage and rotation angle measured with the liquid metal coil during eye movement accords well with that of the classical copper scleral search coil, with both determination coefficients over 0.98, which confirms the reliability of the new coil. Overall, the feasibility of the liquid metal coil system suggests a useful approach for detecting human eye movement behavior and related diseases, which may facilitate disease diagnosis and prediction.

Chi-Chung Fan

Papers

Liquid Metal Enabled Flexible Electronic System for Eye Movement Tracking