A Breathable and Screen‐Printed Pressure Sensor Based on Nanofiber Membranes for Electronic Skins

Abstract

In recent years, skin‐like pressure sensors with high sensitivity and excellent flexibility are widely demonstrated for electronic skins. However, most of the reported skin‐like pressure sensors are still based on airtight films, resulting in limited air permeability. Herein, cost‐effective and capable processes of large‐scale production are reported for lightweight and breathable pressure sensors based on nanofiber membranes (NM). The pressure sensor is composed of a layer‐by‐layer structure of poly(vinylidene fluoride) NM for substrates, silver nanowires for electrodes, and thermoplastic polyurethane NM for the dielectric layer through screen printing and ultrasonic bonding techniques. Benefiting from the high porosity of NM, the capacitive pressure sensor possesses unique performance, including a superior sensitivity of 4.2 kPa−1, a fast response time (<26 ms), an ultralow detection limit (1.6 Pa), and excellent breathability (Gurley value = 17.3 s/100 mL). Furthermore, the pressure sensor is not only applicable to monitor human physiological signals, but also to detect spatial pressure distribution. These results indicate that the breathable and screen‐print pressure sensor is promising for electronic skins with air permeability.

All‐Fiber Structured Electronic Skin with High Elasticity and Breathability

“…Mater. The PU NFs substrates with high elasticity endow the pressure sensor arrays with excellent shape-adaptability [19] (Video S2, Supporting Information). [28,29] For the sensing layer, Figure S5 (Supporting Information) shows the mechanical properties of the PVDF NFs, suggesting the tensile strength and strain are 19.5 MPa and 120%, respectively.…”

Waterproof and Breathable Electrospun Nanofibrous Membranes

“…Significantly, electrospun W&B nanofibrous membranes exhibit simple productive process, low cost, wide material sources, and controllable structure, and have become a hot point in the development of W&B materials in the past few years and shown a large variety of practical applications in various fields . This section will concentrate on the recent progress in the applications of W&B nanofibrous membranes in the functional garment, medical and sanitary material, membrane distillation system, and electronic and electrical equipment industries …”

“…One more interesting application of electrospun W&B membranes is electronic and electrical equipment . One of the major concerns for electronic and electrical products is the short circuit caused by water intrusion, which generally requires the W&B membranes to prevent water droplet penetration and water vapor condensation.…”

“…Recently, Yang et al . constructed W&B capacitive pressure sensor for electronic skins, which was made up of double PVDF electrospun membranes/silver nanowire composite electrodes and a PU nanofibrous membrane dielectric layer ( Figure a).…”

Fabrication of high‐fracture‐strength and gas‐tightness PDC films via PIP process for pressure sensor application

“…Although the piezoresistivity and piezodielectricity behaviors of certain PDCs have been developed, the relatively low sensitivity, accuracy, and sensing range were still the huge obstacles to a wider utilization of PDC pressure sensors 19,20 . Recently, Yang et al proposed that, the pressure sensor may be more sensitivity when its design is based on the structure of parallel plate capacitor consisting of two parallel metal plates and intermediate insulating material 21 . Su et al 22 and Cheng et al 23 also have done great jobs in increasing sensor accuracy and sensing range.…”