The development of wireless implantable temperature sensors is proposed, for the purpose of evaluation and control of thermal surgery. Thermal surgery, or the thermal destruction of undesired biological tissues- such as cancerous tumors-can be achieved by either freezing (also known as cryosurgery), or by heating, with the examples of high frequency ultrasound (HIFU), radio-frequency ablation (RFA), laser probes, and magnetic nanoparticles in an AC magnetic field. Thermal surgery is a minimally invasive procedure by nature, where its successful application is dependent upon the ability to measure temperatures at critical locations and reconstruct the temperature field in real time. The goal in this line of research is to make temperature-field reconstruction in real time a practical reality. Proof-of-concepts for two key elements are proposed to be developed in the current exploratory study: a miniature wireless temperature-sensing unit and a method to translate temperature data-collected from multiple sensors-to a reconstructed temperature field. While this proposal uses cryosurgery of the prostate as a research model, results of this study are translational to other thermal modalities in medicine. The groundbreaking conceptual design of the new temperature-sensing unit originates from advances in electronics miniaturization and wireless communication. The sensing-unit design consists of three main components: a temperature-sensing core, a wireless transceiver, and a power link. The innovation in this system design is four-fold: (i) the sensor is ultra-miniature-being implanted on a monolithic piece of silicon, where the sensor is of a rice-grain size;(ii) the sensor is passive, receiving its electrical power by means of wireless inductive coupling;(iii) many sensors can communicate simultaneously with a single data receiver; and, (iv) sensor localization can be done under imaging guidance, for example, similarly to radiation seeds localization during brachytherapy (local radiation treatment of the prostate).
Three specific aims are set forth in this exploratory study: (1) to develop a wireless temperature-sensing unit, comprising a silicon implant with on-chip inductively-coupled power regulation, a temperature sensor, and a wireless communication interface;(2) to demonstrate feasibility of temperature sensing on a phantom material, using a prostate-cryosurgery simulator, which is an established experimental testing platform, designed to create a 2D-thermal field simulative of prostate cryosurgery;and, (3) to develop a mathematical technique for real-time temperature-field reconstruction for cryosurgery applications. The wider impact of the proposed line of research far exceeds the application of temperature monitoring, where remote power excitation, combined with wireless communication, can serve as a platform for a battery of sensors, and for a wide range of medical applications.

Public Health Relevance

The objective of this study is to develop a wireless implantable temperature sensor for the purpose of feedback and control of thermal surgery. Two key elements are proposed to be developed in this study: a miniature wireless temperature sensor and a method to collect data from multiple sensors, for temperature field reconstruction. While this proposal uses cryosurgery (i.e., the destruction of tissue by freezing) of the prostate as a research model, the outcomes of this study are expected to be translational to high-temperature thermal-surgery applications, such as high-frequency ultrasound, radio-frequency, and laser probes.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Exploratory/Developmental Grants (R21)
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Bioengineering, Technology and Surgical Sciences Study Section (BTSS)
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Korte, Brenda
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Carnegie-Mellon University
Engineering (All Types)
Schools of Engineering
United States
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