Surgical suture as dipole antenna for wireless monitoring of post-surgical complications

Surgical sutures are passive medical devices which are used to appose tissue at the surgical site and hence are potential platform to build any multi-pronged monitoring and therapeutic strategy. Symptoms of post-surgical complications often appear very late, making the monitoring of surgical site an invasive procedure. In this paper, we have demonstrated that conductive sutures can act as a dipole antenna to monitor the surgical site wirelessly in situ. Wireless sensing sutures are fabricated by coating medical grade sutures with conductive polymer PEDOT:PSS to function as a dipole antenna. The conductivity of the sutures is 1080 S/m. An 8-cm half-wavelength dipole antenna made by wireless sensing sutures shows promising antenna performance at an operational resonant frequency between 1 to 2 GHz. The on-board sensing module composite of LC circuit. Change in permittivity of the capacitor area, due to the variation in environment, causes a change in capacitance, which is realised as change in resonant frequency. Wireless sensing sutures transmit information to an external device through a harmonic backscatter technique in which miniaturized electronics - LC circuit and Schottky diode modulate the signal. Our proof-of-concept studies show that wireless sensing sutures can monitor post-surgical complications like sudden bleeding. Wireless sensing sutures are `active' sutures which can aid in improved patient-centred outcome.