Flexible pressure sensors offer the advantages of flexibility, low cost, and easy to large area fabrication, and they have wide applications in many fields. This work proposes a flexible capacitive pressure sensor that exhibits a sandwich-like structure, a good performance, and a simple process. Multi-walled carbon nanotube (MWNT) is used to fabricate the two electrodes of the sensor because this low cost material possesses good mechanical and electronic properties. Meanwhile, MWNT naturally forms numerous micro-nano structures that can enhance the sensitivity of a sensor. In addition, the dielectric layer of the sensor composed of parylene C (poly(chloro-p-xylylene)) is sandwiched between the two electrodes. The experimental results show that the pressure sensor demonstrates high sensitivity and a rapid response. The average sensitivity is 1.33 kPa-1 at a pressure that ranges from 0 to 758 Pa and the response time reach to millisecond level. Given that low cost, good property and simple process, the sensor has wide application prospects in electronic skins, health monitoring devices, and other wearable electronic products.

Implantable pressure sensors enable more accurate disease diagnosis and real-time monitoring. Their widescale usage is dependent on a reliable encapsulation to protect them from corrosion of body fluids, yet not increasing their sizes or impairing their sensing functions during their lifespans. To realize the above requirements, an ultrathin, flexible, waterproof while robust micro–nano composite coating for encapsulation of an implantable pressure sensor is designed. The composite coating is composed of a nanolayer of silane-coupled molecules and a microlayer of parylene polymers. The mechanism and principle of the composite encapsulation coating with high adhesion are elucidated. Experimental results show that the error of the sensors after encapsulation is less than 2 mmHg, after working continuously for equivalently over 434 days in a simulated body fluid environment. The effects of the coating thickness on the waterproof time and the error of the sensor are also studied. The encapsulated sensor is implanted in an isolated porcine eye and a living rabbit eye, exhibiting excellent performances. Therefore, the micro–nano composite encapsulation coating would have an appealing application in micro–nano-device protections, especially for implantable biomedical devices.

Flexible electrodes are extensively used to detect signals in electrocardiography, electroencephalography, electro-ophthalmography, and electromyography, among others. These electrodes can also be used in wearable and implantable medical systems. The collected signals directly affect doctors’ diagnoses of patient etiology and are closely associated with patients’ life safety. Electrodes with low contact impedance can acquire good quality signals. Herein, we established a method of arraying pyramidal microstructures on polydimethylsiloxane (PDMS) substrates to increase the contact area of electrodes, and a parylene transitional layer is coated between PDMS substrates and metal membranes to enhance the bonding force, finally reducing the impedance of flexible electrodes. Experimental results demonstrated that the proposed methods were effective. The contact area of the fabricated electrode increased by 18.15% per unit area, and the contact impedance at 20 Hz to 1 kHz scanning frequency ranged from 23 to 8 kΩ, which was always smaller than that of a commercial electrode. Overall, these results indicated the excellent performance of the fabricated electrode given its low contact impedance and good biocompatibility. This study can also serve as a reference for further electrode research and application in wearable and implantable medical systems.

Excellent flexibility, high sensitivity, and low consumption are essential characteristics in flexible microtube pressure sensing occasion, for example, implantable medical devices, industrial pipeline, and microfluidic chip. This paper reports a flexible, highly sensitive, and ultrathin piezoresistive pressure sensor for fluid pressure sensing, whose sensing element is micropatterned films with conductive carbon nanotube layer. The flexible pressure sensor, the thickness of which is 40 ± 10 μm, could be economically fabricated by using biocompatible polydimethylsiloxane (PDMS). Experimental results show that the flexible pressure sensor has high sensitivity (0.047 kPa−1in gas sensing and 5.6 × 10−3 kPa−1in liquid sensing) and low consumption (<180 μW), and the sensor could be used to measure the pressure in curved microtubes.