Self-Powered, Ultrathin, and Transparent Printed Pressure Sensor for Biosignal Monitoring

Abstract

Ultrathin sensing devices utilizing piezoelectric materials have emerged as potential candidates to develop highly skin-conformable and energy-efficient continuous biosignal monitoring systems. However, biocompatible, cost-efficient, and simple fabrication processes still need to be investigated to enable wider adoption of such devices. This study proposes a simple two-step printing process for the fabrication of a piezoelectric biosignal sensor that utilizes readily available and biocompatible polymer-based materials for the substrate (i.e., Parylene-C), electroactive layer (i.e., poly­(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)), and interdigitated electrodes (i.e., poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS)). The proposed interdigitated electrode architecture improves upon the conventional metal–insulator–metal architecture by (1) increasing the thickness-normalized output voltage and (2) enabling the detection of bending orientation. The performance of the proposed sensor structure is demonstrated with the measurement of the arterial pulse waveform signal and limb movement detection. The presented results pave the way for cost-effective and continuous unobtrusive on-skin biosignal monitoring.

Screen-Printed Piezoelectric Sensors on Tattoo Paper Combined with All-Printed High-Performance Organic Electrochemical Transistors for Electrophysiological Signal Monitoring

“…In 2021, monitoring of the arterial pulse rate was demonstrated using a self-powered piezoelectric sensor based on an interdigitated structure on Parylene-C; the device was fabricated via a mix of deposition techniques, i.e., chemical vapor deposition (CVD), inkjet printing, and automatic wire bar coating . In 2022, the same group reported on arterial pulse wave monitoring with a highly sensitive device manufactured by using a similar substrate and fabrication strategy .…”

Recent progress in thermal management for flexible/wearable devices

“…The design and development of advanced wearable devices still pose challenges because of the need to integrate electronic, electrochemical, electro-optical, or multiple types of functionality on a platform that is soft, compact, lightweight, flexible, and stretchable [12,13] . To do so, various manufacturing technologies, such as laser processing [14][15][16][17] , transfer printing [18][19][20][21] , and inkjet printing [22][23][24][25][26] , have been used to fabricate a flexible/stretchable device platform. Ensuring long-term reliability and biocompatibility during human body motion, especially in outdoor activities involving external heat exposure and metabolic heat generation, adds to the challenges in material/structure development and device design.…”

Multimodal Finger Pulse Wave Sensing: Comparison of Forcecardiography and Photoplethysmography Sensors

“…Unlike applanation tonometry, piezoelectric sensors capture PW signals without the need for arteries to be flattened, thus being suitable for wearable, long-term monitoring of PWs [ 74 ]. Several approaches based on piezoelectric sensors have been described featuring different materials, geometry, and numbers of required sensing elements to be placed on subjects’ bodies [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ]. Wang et al described a rigid piezoelectric sensor applied on the wrist to measure PW signals and estimate blood pressure via PW analysis [ 76 ].…”

“…Dagdeviren et al proposed a multichannel PW sensor based on an 8 × 8 matrix of lead zirconate titanate (PZT) sensors mounted on a thin, flexible substrate of silicone rubber [ 80 ]. Lozano Montero et al designed a fully printed, biocompatible, ultrathin piezoelectric sensor, made of poly(vinylidene fluoride-trifluoro-ethylene) (PVDF-TrFE), capable of acquiring PW signals from the radial artery in the wrist for accurate blood pressure estimation as compared to a commercial finger-cuff medical BP monitor [ 81 ]. Guo et al presented a high-sensitivity piezoelectric PW sensor with a specific mechanical design, which proved capable of capturing the changes in hemodynamic parameters that occur during premature atrial and/or ventricular contractions, and also for accurate blood pressure monitoring in patients with arrhythmias [ 82 ].…”

“…Such a comparison has led to a deeper comprehension of their strengths and weaknesses, and ultimately, to the consideration that a multimodal approach accomplished via sensor fusion would lead to a more robust, reliable, and potentially more informative methodology for PW monitoring. However, apart from various multichannel or multi-site systems proposed in the literature [ 11 , 107 , 108 ] and the comparison/integration of different sensors applied on different body parts [ 81 , 100 , 109 ], no true multimodal sensors for PW recording have been proposed yet that acquire PW signals simultaneously from the same body site.…”