Characterisation and testing of a 'smart' needle

As the world of smart technology advances, insensate objects are being transformed to 'smart' devices by the application of sensors. Our research focuses on applying an impedance sensor to a hypodermic needle to create a 'smart' needle. This novel device will use bioimpedance to determine needle-to-nerve proximity for application in ultrasound guided peripheral nerve block (USgPNB) procedures. Bioimpedance data from the needle tip will allow for real-time tissue identification and thus provides the user with the exact needle tip location. For anaesthetists it will provide valuable information indicating needle contact with the nerve covering or dangerous needle position within the nerve. Introduction of this new technology to USgPNB will increase its safety, efficacy and training capacity thus increasing the use of the technique and reducing costs for the healthcare system, as it is a safer quicker alternative to general anaesthesia. The impedance sensor on the 'smart' needle is a miniaturised two electrode set-up. This paper discusses the characterisation and testing of the 'smart' needle. Impedance values using this device are provided for various electrolyte solutions and bioimpedance of different tissue types are presented. Comparisons are drawn between these results and the results of a feasibility study conducted using a 'macro-needle' in similar configuration to the 'smart' needle. Plans for further testing and adaptation of the needle towards in vivo animal testing in a pig model are also detailed.