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.

The real-time monitoring of the working status of drainage tubes is crucial for successful surgical drainage and for informing clinicians of the drainage conditions of patients at different stages, to enable objective diagnosis and treatment. In this study, a method for monitoring the drainage condition of drainage tubes was proposed. The method was based on the principle of capacitance and was developed by analyzing the major states of drainage tubes in the process of drainage. Meanwhile, the principle of interdigital capacitance monitoring drainage was analyzed, and an interdigital capacitance device for the real-time monitoring of the working status of drainage tubes was designed. Ultimately, an experimental system for drainage simulation was established on the basis of the interdigital capacitance device and method for drainage monitoring. Results showed that the interdigital capacitance device for drainage monitoring can identify unobstructed or blocked drainage tubes effectively in real time. The device has a hydrophobic surface, so its electrodes do not undergo electrolysis and pollution due to adhesion. Hence the proposed capacitance-based method for monitoring the working states of drainage tubes has good application prospects in the postoperative drainage of abdominal and thoracic cavities.