All‐in‐One Iontronic Sensing Paper

Abstract

Paper has been utilized as an ideal platform for chemical, biological, and mechanical sensing for its fibrous structures and properties in addition to its low cost. However, current studies on pressure-sensitive papers have not fully utilized the unique advantages of papers, such as printability, cuttability, and foldability. Moreover, the existing resistive, capacitive, and triboelectric sensing modalities have long-standing challenges in sensitivity, noiseproofing, response time, linearity, etc. Here, a novel flexible iontronic sensing mechanism, referred to as iontronic sensing paper (ISP), is introduced to the classic paper substrates by incorporating both ionic and conductive patterns into an all-in-one flexible sensing platform. The ISP can then be structured into 2D or 3D tactile-sensitive origamis only by the paper-specific manipulations of printing, cutting, folding, and gluing. Notably, the ISP device possesses a device sensitivity of 10 nF kPa −1 cm −2 , which is thousands of times higher than that of the commercial counterpart, a resolution of 6.25 Pa, a single-millisecond response time, and a high linearity (R 2 > 0.996). Benefiting from the unique properties of the fibrous paper structures and its remarkable performances, the ISP devices hold enormous potential for the emerging human-machine interfaces, including smart packaging, health wearables, and pressure-sensitive paper matrix.

Stretchable Sensors with Tunability and Single Stimuli-Responsiveness through Resistivity Switching Under Compressive Stress

“…29,34−36 Other efforts have focused on material development, such as creating supercapacitive iontronic sensing with an exceptionally high unit-area capacitance aiming toward excellent sensing capabilities. 37,38 Yet there still exist only a few pressure sensors that can maintain a high sensitivity of >50 kPa −1 in the medium pressure regime (up to 100 kPa), thus capable of more closely mimicking the tactile sensing capabilities of natural skin. 5,23,26,31 Structural design strategies for single stimuli-responsiveness and discrimination of other tactile inputs have not been fully explored to date.…”

Disruptive, Soft, Wearable Sensors

“…with at least three orders of magnitude larger than that of the EDL‐free counterparts. When ionic liquids are used as electrolytes for EDL, they can offer wide electrochemical sensing windows in field‐effect transistor beneficial for wearable electronics …”

Ionic Tactile Sensors for Emerging Human‐Interactive Technologies: A Review of Recent Progress

“…In order to resolve this, an analytic model is developed by considering the ideal case i) where all the fibers are oriented randomly and distributed uniformly; ii) pressure‐induced bending of the individual fibers causes the change in the volume fraction of the fibers ( V f ) in the assembly, and successively affects the variation of the area fraction of the fibers at interfaces. The device capacitance and the sensitivity can be represented by Equations and , respectively where V f0 represents the initial volume fraction of the fibers assembly at zero pressure and K is a constant related to the force distribution on the fibers and can be derived from a classic bending formula of a simply supported beam.…”

“…In literature, many supercapacitive ITS reports have defined the pressure sensitivity ( S (nF kPa −1 ) = Δ C/ Δ P ) as the ratio of the change in capacitance (Δ C ) to the change in applied pressure (Δ P ), which has reached up to a value of few hundreds of nF kPa −1 (≈1000 times higher than conventional capacitive sensors), and represented an advantage over conventional resistive and capacitive tactile sensors . However, for quantitative analysis and better comparison between the ITS and their conventional counterparts, some of the supercapacitive ITS reports calculate pressure sensitivity similar to the conventional capacitive sensors, which is given by S (kPa −1 ) = δ (Δ C/C 0 ) /δP , where C 0 denotes the ionic sensor capacitance in no pressure condition .…”

“…The increase in contact area between CNT microyarns and i‐TPU/CNT microyarns under the application of external pressure increased EDL capacitance at the interface, which allowed the detection of a wide range of pressures; from subtle pressure (15 Pa) and gentle pressure (1–10 kPa) such as human touch to heavy pressures used in daily activities (up to 150 kPa) (Figure biii). Very recently, the same group introduced an iontronic sensing paper by incorporating both ionic and conductive patterns to the classic paper substrates to develop all‐in‐one flexible sensing platform . The iontronic sensing paper can be structured into 2D or 3D pressure/force‐sensitive devices only by paper specific manipulations, such as printing, cutting, folding, and gluing.…”