Wide-Sensing-Ranged PANI:PEO Piezoresistive Pressure Sensor Array in Pressure Distribution Monitoring on Cervical Disks Under Neck Flexion

Recently, phubbing has led to a significant increase in neck-related diseases such as cervical disk (CVD) herniation. CVDs experience a typical pressure of approximately 200 kPa in the upright position, which increases dramatically with the degrees of flexion. Thus, there is a high probability for patients who have undergone the cervical artificial disk replacement surgery to have the revision surgery owing to inappropriate postures. Herein, a highly sensitive piezoresistive pressure sensor array with a wide sensing range of up to 1000 kPa, using polyethylene oxide (PEO) as the sensing membrane and polyaniline (PANI) as the conductive filler, is proposed to real-time monitor the pressure distribution on CVDs. The optimal PANI doping concentration in PANI:PEO composite films was determined to be 0.1%, which demonstrated excellent sensitivity of 0.279 kPa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula>, a high coefficient of determination (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R} ^{{2}}$ </tex-math></inline-formula>) of 0.959, and a short relaxation time of 0.72 s of the PANI:PEO piezoresistive pressure sensors. To accommodate the sensor array within the limited space of the cervical vertebrae, the electrode size of the devices was significantly reduced to less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu $ </tex-math></inline-formula>m to realize a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 3$ </tex-math></inline-formula> PANI:PEO piezoresistive pressure sensor array. The fabricated pressure sensor array effectively monitored the pressure distribution on CVDs in a cervical spine model with a full cervical spine and dual cervical vertebrae under different flexion angles, holding favorable potential to avoid further CVD herniation after the cervical artificial disk replacement surgery.