Three-Dimensional Printed Stimulating Hybrid Smart Bandage

Abstract

The treatment of chronic wounds and pressure sores is an important challenge in the context of public health and the effectiveness of patient treatment. Therefore, new methods are being developed to reduce or, in extreme cases, to initiate and conduct the wound healing process. This article presents an innovative smart bandage, programmable using a smartphone, which generates small amplitude impulse vibrations. The communication between the smart bandage and the smartphone is realized using BLE. The possibility of programming the smart bandage allows for personalized therapy. Owing to the built-in MEMS sensor, the smart bandage makes it possible to monitor work during rehabilitation and implement an auto-calibration procedure. The flexible, openwork mechanical structure of the dressing was made in 3D printing technology, thanks to which the solution is easy to implement and can be used together with traditional dressings to create hybrid ones. Miniature electronic circuits and actuators controlled by the PWM signal were designed as replaceable elements; thus, the openwork structure can be treated as single-use. The smart bandage containing six actuators presented in this article generates oscillations in the range from about 40 Hz to 190 Hz. The system generates low-amplitude vibrations, below 1 g. The actuators were operated at a voltage of 1.65 V to reduce energy consumption. For comparison, the actuators were also operated at the nominal voltage of 3.17 V, as specified by the manufacturer.

Keywords: IoT; embedded system; mobile; smart; wearable; wound healing.

Figure 1

Openwork bandage structure.

Figure 2

Images of (a) vibrating engine (actuator); (b) printed housing of the MT24 vibrating engine.

Figure 3

The architecture of central module (CM, controller).

Figure 4

System components: skeletal smart bandage and smartphone.

Figure 5

View of the accelerometer placed in the slot in the central part of openwork structure.

Figure 6

Images of the tested system from the thermal imaging camera: (a) before starting work; (b) after 15 min of working; (c) after 30 min; (d) after 1 h.

Figure 7

Changes in the temperature of the system (SSB) during operation: (a) dependence of the temperatures of the actuator and controller (CM) on working time; (b) box-and-whisker plots.

Figure 8

Results of the mechanical strength simulation of FOS made of nylon: (a) visualization of the impact of the applied force (35 N) on structure stretching; (b) visualization of the impact of the applied force (35 N) on stress; (c) a graph of the dependence of the structure shift on the applied stretching forces; (d) dependence of the structure stress on the applied stretching forces.

Figure 9

Screenshots from the smart bandage mobile application.

Figure 10

Amplitude of oscillation when placing the smart bandage on the flat surface and supplying actuators with reduced voltage of 1.65 V, before and after calibration, respectively, for the following: (a) resultant acceleration vector and its individual components; (b) along the x-axis; (c) along the y-axis; and (d) along the z-axis.

Figure 11

Current consumption by individual oscillators at nominal supply voltage (3.17 V) and at voltage reduced to 1.65 V.

Figure 12

Forearm phantom for testing the smart bandage on the convex surface (on the printed model of the upper limb fragment).

Figure 13

Amplitude of oscillations for the resultant acceleration vector without calibration and after calibration for individual actuators (on the flat surface and at 1.65 V supply), depending on the material from which the openwork structure was made: (a) nylon; (b) PP; and (c) TPU.

Figure 14

Amplitude of oscillation for the resultant acceleration vector without calibration and after calibration for individual actuators (on the forearm phantom and at 1.65 V supply), depending on the material from which the openwork structure was made: (a) nylon; (b) PP; and (c) TPU.

Figure 15

Amplitude of oscillation for the resultant acceleration vector without calibration and after calibration for individual actuators (on the forearm phantom and at 3.17 V supply), depending on the material from which the openwork structure was made: (a) nylon; (b) PP; and (c) TPU.

Figure 16

FFT analysis results for two actuators (placed on the flat surface and at 1.65 V supply) depending on the material from which the smart bandage openwork structure was made: (a) nylon; (b) PP; and (c) TPU.

Figure 17

FFT analysis results for two actuators (placed on the forearm phantom and at 3.17 V nominal supply) depending on the material from which the smart bandage openwork structure was made: (a) nylon; (b) PP; and (c) TPU.