Challenge: NextPhase Medical Devices was tasked with the development of a device that would abrade the skin to a precise depth, just below the stratum corneum, accessing the interstitial fluid found immediately under the outermost layer of the epidermis. This device would prep a small area of skin so that a sensor could sample the interstitial fluid for blood glucose level reporting. The device would offer the additional therapeutic advantage of easy access to interstitial fluid for improved absorption of skin-applied drugs such as Lidocaine.
Design Concept: The key product design requirement was the ability to control abrasion depth to minimize pain and injury to the patient, while still reaching the proper skin layer to conduct effective diagnostics of the interstitial fluid. Studies were conducted to determine fluid levels at various skin layers, and it was determined that enough fluid could be accessed to measure glucose levels at just .01 mm beneath the outermost epidermis layer. Sensors would have to be added and designed to communicate with the motor and offer a shut-off signal when the proper amount of fluid was detected. Initial concepts were iterated with battery-driven, high-speed motors rotating a fine, circular abrasive tool. Human factors were studied to offer the optimum features for clinical adoption of the handheld device and size of the base station charger. Micro fluidic levels would be measured by the electronics and software algorithms that would be developed to control the device.
NextPhase developed a custom, rechargeable, battery-powered hand piece with a motor-driven rotating drum, coated with abrasive media, to abrade the skin. The drum and concealing nose piece were designed as single-use disposable items. Sensors were developed and integrated into the design to measure the skin’s electrical conductivity, which improves with increased moisture levels; tests were performed to determine proper fluid levels. Proprietary algorithms were then developed, tested, perfected, and bundled with the control electronics to allow real-time measurement of electrical conductivity of a prepared skin test site. The software was then able to determine the optimum moisture level indicating that the drum had reached the clinically approved depth, and then shut off the device immediately.
This medical device has been built for clinical trial and is being used in concert with a wearable diagnostic device designed to detect and wirelessly report on a patient’s blood glucose levels. The entire procedure is completed in 15 to 20 seconds with no noticeable pain or discomfort to the patient.