Highly Stretchable Graphene Scrolls Transistors for Self-Powered Tribotronic Non-Mechanosensation Application

Abstract

Owing to highly desired requirements in advanced disease diagnosis, therapy, and health monitoring, noncontact mechanosensation active matrix has drawn considerable attention. To satisfy the practical demands of high energy efficiency, in this report, combining the advantage of multiparameter monitoring, high sensitivity, and high resolution of active matrix field-effect transistor (FET) with triboelectric nanogenerators (TENG), we successfully developed the tribotronic mechanosensation active matrix based on tribotronic ion gel graphene scrolls field-effect transistors (GSFET). The tribopotential produced by TENG served as a gate voltage to modulate carrier transport along the semiconductor channel and realized self-powered ability with considerable decreased energy consumption. To achieve high spatial utilization and more pronounced responsivity of the dielectric of this transistor, ion gel was used to act as a triboelectric layer to conduct friction and contact electrification with external materials directly to produce triboelectric charges to power GFET. This tribopotential-driving device has excellent tactile sensing properties with high sensitivity (1.125 mm^-1), rapid response time (~16 ms), and a durability operation of thousands of cycles. Furthermore, the device was transparent and flexible with the capability of spatially mapping touch stimuli and monitoring real-time temperature. Due to all these unique characteristics, this novel noncontact mechanosensation GSFET active matrix provided a new method for self-powered E-skin with promising potential for self-powered wearable devices and intelligent robots.

Keywords: graphene scrolls; ion gel; mechanosensation; tribotronic.

Figure 1

(a) Schematic illustration of the noncontact mechanosensation active matrix based on the tribotronic planar graphene transistors array. Inset is the zoomed-in schematic diagram of the single sensing unit. (b) Structure and microscopy image of the trilayer graphene scrolls. (c) UV-vis transmittance spectrum of PDMS, trilayer graphene scrolls on PDMS, and GSFET on PDMS, respectively. Inset is the photo image of transparent trilayer graphene scrolls.

Figure 2

Electrical properties of GFET/GSFET under deformation. (a) Normalized relative resistance change of monolayer graphene, bilayer graphene scrolls, trilayer graphene, and trilayer graphene scrolls as a function of perpendicular (left panel) and parallel (right panel) stretch and strain to the direction of current flow. (b) I-V curve of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel) at varied strain deformations. (c) Transfer curve of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel) at varied strain deformations (at given V_D of 0.1 V). (d) I–V curve of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel) at varied bending deformations. (e) Transfer curve of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel) at varied bending deformations.

Figure 3

(a) The IV character of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel) (graphene films transferred on Ecoflex were patterned into 500 μm-wide and 2000 μm-long channels by photolithography). (b)The extracted relative resistance variation (R − R₀)/R₀ of trilayer graphene scrolls (top panel) and monolayer graphene (bottom panel). (c) Transfer characteristic of GSFET (top panel) and GFET (bottom panel) under varied temperature. (d) The real-time temperature monitoring of GFET (right panel) and GSFET (left panel).

Figure 4

Triboelectric properties of the tribotronic GSFET. (a) Schematic illustration of the GSFET device. (b) Circuit diagram of tribotronic GSFET sensor contact with skin. (c) Output characteristic (left panel) and transfer characteristic (right panel) of GSFET by triboelectric driving. (d) Output characteristic (left panel) and transfer characteristic (right panel) of trilayer graphene scroll transistor by tribotronic potential (right panel). (e) Durability test over 3000 cycles of contact and separation (left panel) and retentivity during the last cycles (right panel). For E-skin application, ion gel dielectric was carried out friction with skin. Figure 4b shows the scheme of the working principle of ion gel-triboelectric gated GSFET. The tribo-potential, induced by friction between the ion gel and skin, causes the accumulation of negative charges on the surface of the ion gel, attracting compensating cations in the ion gel, while the anions in the ion gel migrate to the ion gel/graphene interface, acting as a negative gating potential for the graphene channel. Consequently, the electrons accumulate in graphene channel. The output characteristic of GFET under an applied gate (Figure 4c left panel) displays that the drain current (I_D) exhibits a linear relationship with drain voltage V_DS and increases values as gate voltage V_G increases (from 68.7 μA to 98.5 μA with V_G increased from 0 V to 2 V at a V_D of 0.5 V). The transfer curve (Figure 4c right panel) displays that the I_D values increased with increased V_G in both positive and negative directions, indicating an ambipolar charge transport property of graphene. The GFET operated at a low gate voltage (<2 V) due to the extreme high capacitance of the ion gel gate dielectric (6–7 μF/cm²).

Figure 5

Characterization of GSFET noncontact mechanosensation active matrix. (a) Schematic illustration of the mechanosensation matrix for sensing the distance information and temperature. (b) 2D mapping of the distance sensing output currents for the matrix. (c) 2D mapping of the temperature sensing output currents for the matrix. (d) The real-time temperature monitoring and distance monitoring between the ion gel and skin. (e) 2D mapping of the distance sensing output currents for the matrix as the device is attached onto the human’s knee joint and conforms to it. (f) 2D mapping of the temperature-sensing output currents for the matrix as the device is attached onto the human’s knee joint and conforms to it.