An Automated Test System for Measuring and Improving Electrosurgical Effects Anup Amin 1, 2 , Daniel Friedrichs 2 , Carolyn Ford 2 , Eric Larson 2 , and James Gilbert 2 1 University of Texas at Arlington, Arlington, TX, USA 2 Covidien Surgical Solutions, Boulder, CO, USA Abstract – Designing instruments and power supplies for electrosurgery (a critical tool in modern surgical practice) is a difficult proposition; a large number of competing variables affect an even larger number of electrosurgical performance metrics. This paper describes the design of an apparatus used to tightly control experimental variables, record high-speed data from numerous sensors, and process the results into a form which better elucidates the underlying physical mechanisms and gives insight into potential design improvements. Index Terms—Electrosurgery, automated testing, data acquisition I. INTRODUCTION Electrosurgery is a technology regularly employed in modern operating rooms to enable tissue division and dissection with concomitant hemostasis. When passed through tissue, high-frequency electrical current can cause sufficient joule heating to cause both a cutting and coagulating effect [1]. Electrosurgery is an indispensable tool in modern surgical practice, finding use in over 80% of procedures performed in the United States [2]. Despite the importance and prevalence of electrosurgery, the technology has seen only superficial changes since its conception by Dr. William T. Bovie in 1920 [3]. Further, the physical mechanisms underlying the electrosurgical effect are still not fully elucidated, partially owing to the large number of involved variables which influence a large number of competing metrics of surgical effectiveness. For instance, high peak voltages from the electrosurgical instrument tend to improve hemostasis, at the expense of producing more smoke which obscures vision and is potentially mutagenic or carcinogenic [4]. In general, performance metrics of interest to the surgeon include cutting speed, level of hemostasis, cutting force, smoke/steam produced, electric arcs produced, and consistency [6]. The variables that influence these metrics include tissue type, tissue volume, applied voltages and currents, cutting speed, and instrument geometry. The inability to experimentally control this large set of interconnected variables has previously obstructed efforts to better understand the underlying physical mechanisms of electrosurgery. The goal of this work is to construct an apparatus which will allow consistent and repeatable control over several contributory variables, in order to better isolate parameters which may improve performance of electrosurgical tools. Section II of this paper describes the design and construction of said apparatus, detailing methods of improving control and facilitating isolated measurements. Section III presents several example results garnered from the apparatus, illustrating the benefits of precise and repeatable control. Section IV summarizes the results and offers future research directions. II. THE GANTRY SYSTEM The test apparatus (termed the “Gantry”) is described in terms of its hardware components (Section IIA), and software components (Section IIB). A. Hardware The hardware for the experimental apparatus consists of a system which acquires and processes signals, and a system which automates a test procedure to yield consistent results by eliminating human-user-induced variability. The hardware can thus be broken into two categories: (1) sensors, and (2) motion control. 1) Sensors The sensors connected to the experimental apparatus allow measurement of the following physical phenomena: a) Voltage and Current: These electrosurgical signals are used to calculate power and impedance. Accurately measuring voltage is difficult because of the high-frequency of the AC current (500 kHz), the high potential difference generated (up to 10kV), and the fact that the electrosurgical generator output is not ground-referenced. A Tektronix® P5205A 100MHz high-voltage differential voltage probe overcomes these obstacles and permits wide-bandwidth measurement of the voltage. The current measurement also needs to be wide-bandwidth, as well as both DC and AC coupled. A Tektronix® TCP0030 AC/DC current probe satisfies these requirements. b) Force: The drag force on the surgical instrument is another metric that affects the user’s perceived quality of the electrosurgical cut. The drag force varies as the type of tissue varies, but is also dependent on power supply parameters. Torque on the electrosurgical instrument is measured by a high-sensitivity flange-mounted 5 oz/in reaction torque U.S. Government work not protected by U.S. copyright