Figure 2
System overview. (a) Sensor probe details. One unit consists of three sensors which continuously monitor pulse waveforms, tissue colour, and tissue temperature. These three components were selected because the efficacy of pulse waveforms has been previously studied, and tissue colour and temperature are the key features assessed by surgeons during postoperative care in a clinical setting14,47. This probe is an array of units with four channels, which can be configured according to the graft size. The flexible sensor conforms to various shapes and positions on the body. (b) Adapting the sensor. First, a medical dressing film was placed on the skin. Then, a polydimethylsiloxane sheet was placed beneath the sensor probe to ensure the sensor remains attached despite its surface irregularities. The sensor probe was then fitted. Lastly, another medical dressing film was used to cover the sensor and keep it attached to the skin. (c) Overview of the system setup. Data were transmitted via Bluetooth to a tablet, where they could be displayed and analysed. We created a smartphone/tablet application to store and visualise the data collected by the sensor to enhance the device’s versatility. This would enable several physicians to receive alarms and notifications when a blood circulation issue is suspected. Moreover, they could access the data at any time by installing the application on their own device. (d) Flexibility supporting the wearability of the sensor. Participants included patients who underwent breast reconstruction after breast cancer treatment, head and neck reconstruction after carcinoma treatment, limb reconstruction after trauma, among others. The sensor was flexible enough to adapt to these variously curved surfaces.
