Micropatterned Pyramidal Ionic Gels for Sensing Broad-Range Pressures with High Sensitivity

Abstract

The development of pressure sensors that are effective over a broad range of pressures is crucial for the future development of electronic skin applicable to the detection of a wide pressure range from acoustic wave to dynamic human motion. Here, we present flexible capacitive pressure sensors that incorporate micropatterned pyramidal ionic gels to enable ultrasensitive pressure detection. Our devices show superior pressure-sensing performance, with a broad sensing range from a few pascals up to 50 kPa, with fast response times of <20 ms and a low operating voltage of 0.25 V. Since high-dielectric-constant ionic gels were employed as constituent sensing materials, an unprecedented sensitivity of 41 kPa in the low-pressure regime of <400 Pa could be realized in the context of a metal-insulator-metal platform. This broad-range capacitive pressure sensor allows for the efficient detection of pressure from a variety of sources, including sound waves, a lightweight object, jugular venous pulses, radial artery pulses, and human finger touch. This platform offers a simple, robust approach to low-cost, scalable device design, enabling practical applications of electronic skin.

Flexible, Transparent, Sensitive, and Crosstalk‐Free Capacitive Tactile Sensor Array Based on Graphene Electrodes and Air Dielectric

“…In addition, complicated circuit arrangement for multipoint recognition is regarded as a drawback to be addressed. [7,16] Compared to resistive tactile sensing mechanisms, capacitive tactile sensors have advantages in terms of temperature independence, low power consumption, stability against long-term signal drift, and easy multipoint recognition by simple assembly of row and column electrodes. [16,17] In general, the structure of a capacitive sensor consists of two parallel electrodes with a dielectric layer between them.…”

Block copolymer structural color strain sensor

“…The screw dislocations that act as channels for transporting the ionic liquid into the QP2VP domains are apparent More importantly, the ionic liquid that is miscible with the QP2VP domains and causes them to swell plays a key role in reducing the mechanical failure during repetitive strain/release cycles when combined with the aforementioned unique confined geometry of the BCP film. Since the QP2VP domains become elastic due to the plasticization of the polymers with ionic liquid 4,38 , no large fracture of the film was observed, and the buckled structure was much finer when a BCP film with ionic liquid embedded in PDMS was stretched to 100% strain than that without ionic liquid, as shown in Fig. 4c.…”

“…Numerous sensors have been demonstrated. The three major mechanical-to-electrical conversion principles are the capacitance [3][4][5][6][7][8] , piezo-electricity 9,10 , and piezoresistivity [11][12][13][14][15][16][17] . Piezo-based sensors rely upon either electrical voltage or resistance changes under mechanical deformation.…”

“…On the other hand, capacitive sensors utilize capacitance changes in pressure-sensitive dielectric films under mechanical stimuli. These sensors are advantageous owing to their fast response times and compact circuit layouts with vertically stacked device architectures [3][4][5][6][7] . To make these sensors suitable for various applications, particularly for largely deformable strain detection, the sensing materials should be either elastomeric or efficiently embedded in a rubbery matrix.…”

“…These requirements make the sensors tolerant to repetitive deformation [6][7][8] . Numerous previous works have been devoted to developing elastomer-based dielectrics for enhancing the sensitivity through efficient large-scale integration by combining a variety of structural architectures [3][4][5]8 . These efforts have provided data supporting the relevance of these capacitive sensors.…”