A highly sensitive, low-cost, wearable pressure sensor based on conductive hydrogel spheres

Abstract

Wearable pressure sensing solutions have promising future for practical applications in health monitoring and human/machine interfaces. Here, a highly sensitive, low-cost, wearable pressure sensor based on conductive single-walled carbon nanotube (SWCNT)/alginate hydrogel spheres is reported. Conductive and piezoresistive spheres are embedded between conductive electrodes (indium tin oxide-coated polyethylene terephthalate films) and subjected to environmental pressure. The detection mechanism is based on the piezoresistivity of the SWCNT/alginate conductive spheres and on the sphere-electrode contact. Step-by-step, we optimized the design parameters to maximize the sensitivity of the sensor. The optimized hydrogel sensor exhibited a satisfactory sensitivity (0.176 ΔR/R0/kPa(-1)) and a low detectable limit (10 Pa). Moreover, a brief response time (a few milliseconds) and successful repeatability were also demonstrated. Finally, the efficiency of this strategy was verified through a series of practical tests such as monitoring human wrist pulse, detecting throat muscle motion or identifying the location and the distribution of an external pressure using an array sensor (4 × 4).

Porous Ionic Membrane Based Flexible Humidity Sensor and its Multifunctional Applications

“…Especially, the rapid advances in the design of various flexible sensors have tremendously broadened the scope of flexible electronics to new classes of soft electronic systems 4, 5. For example, the flexible pressure and temperature sensors can be proposed for deriving various applications including the skin‐like electronics (E‐Skin), robotics human–machine interfaces, and biomedical applications 6, 7, 8, 9, 10. On the other hand, flexible humidity sensors were rarely reported, though humidity is one of most‐intensively measured variables in our daily lives, including comfortable living environment, medical facilities, and body health information 11.…”

Effects of oxidant and dopants on the properties of cellulose/PPy conductive composite hydrogels

“…Shin et al 10 investigated chitosan/polyaniline semi-interpenetrating network polymers under different pH conditions. Tai 11 and Qu 12 use the alginate as matrix to obtain the conductive hydrogels with various conductive substances. However, some of these biodegradable polymers are not feasible to fabricate the hydrogels and some of them form the physical hydrogels with low mechanical properties.…”

Highly Mechanical and Fatigue‐Resistant Double Network Hydrogels by Dual Physically Hydrophobic Association and Ionic Crosslinking

“…Hydrogels are soft and wet materials containing a large amount of water with a 3D crosslinking network structure, which have been widely applied to many fields, such as tissue engineering, [1] cartilage repair, [2,3] artificial implants, [4] wound dressings, [5] and wearable sensors. [6] However, the applications of most hydrogels are always limited by their weak and brittle mechanical properties, most hydrogels possess fracture energy only about 10 Jm −2 , which is much lower than that of cartilage (1000 Jm −2 ). [7] The low mechanical strength and poor toughness of hydrogels result from the lack of efficient energy dissipation mechanism.…”