Implantable physical sensors for in vivo organ monitoring

Implantable sensors can provide access to accurate, continuous, and minimally invasive monitoring of physiological signals from internal organs and tissues, thereby facilitating timely diagnosis, closed-loop intervention, and advanced health management. Among the various types of implantable sensors, those capable of measuring physical parameters–such as temperature, force, and flow–are particularly important due to their ability to monitor physical conditions critical to nearly all organs and to provide insights into a wide range of health conditions.

The team led by Hangbo Zhao from University of Southern California reviews recent progress in four key types of implantable physical sensors: strain sensors, pressure sensors, temperature sensors, and flow sensors. It covers their engineering principles, design considerations, in vivo performances, and clinical relevance. The review also addresses critical challenges and future opportunities in the development of implantable physical sensors, such as flexibility and stretchability, biocompatibility, long-term stability, and the translation of these sensing technologies from bench to clinic.

Implantable physical sensors have the potential to revolutionize medical and healthcare practices by enabling direct, real-time acquisition of critical physiological signals from internal organs and tissues. These sensors - including strain, pressure, flow, and temperature sensors - may significantly advance patient care, facilitate early diagnosis, and enhance treatment efficacy across various medical disciplines. Implantable strain sensors are vital for monitoring biomechanical changes within organs, muscles, and bones, providing crucial data on organ volume fluctuations, tissue stiffness, and motion rhythms. This information is essential for assessing post-surgical recovery and managing chronic conditions. Implantable pressure sensors, particularly those used to monitor ICP and cardiovascular parameters, deliver real-time data critical for managing traumatic brain injuries, heart diseases, and hypertension. Similarly, implantable flow sensors, especially in vascular applications, enable continuous monitoring of blood flow, which is essential for managing conditions such as aneurysms and atherosclerosis. Implantable temperature sensors play a dual role: they monitor organ health, inflammation, and infection, while also integrating with therapeutic tools to regulate tissue temperature during treatments such as electrotherapy and photothermal therapy, thereby supporting precision medicine and enhancing treatment safety. Unlike wearable sensors, implantable sensors must address a range of complex factors, including biocompatibility, flexibility, and stretchability, implantation procedures, long-term stability, as well as power and data transmission. These considerations are critical to ensuring the successful integration and reliable performance of implantable sensors within the human body over extended periods.