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Supplementary Information

Continuous direct current by charge transportation for next-generation

IoT and real-time virtual reality applications

Jianxiong Zhua,b,c,1, Hao Wanga,b,c,d,1, Zixuan Zhanga,b,c,1, Zhihao Rena,b,c, Qiongfeng Shia,b,c, Weixin

Liua,b,c, Chengkuo Leea,b,c,e,*

a Department of Electrical and Computer Engineering, National University of Singapore,

Singapore.

b Center for Intelligent Sensors and MEMS (CISM), National University of Singapore,

Singapore.

c NUS Suzhou Research Institute (NUSRI), Suzhou, China.

d Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology

(SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518035, China.

e NUS Graduate School for Integrative Science and Engineering (NGS), National University of

Singapore, Singapore.

* Correspondence to: elelc@nus.edu.sg (C. Lee).

1 Jianxiong Zhu, Hao Wang, and Zixuan Zhang contributed equally to this work.

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Charges

Low Potential

High Potential

Wire B

Wire A

Figure S1. Inspired by the waterwheel system, a similar mechanism based on charges

generation and charges transportation for a continuous DC output.

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Left-hand Disk

Right-hand Disk

Zero Potential

Potential distribution with a quarter disk area positive and negative charges

Negative charges

Positive charges

Air

Figure S2. FEA (Finite Element Analysis) simulation of the potential distribution on a disk-

carrier. It concluded that the output DC was determined by the rotational speed and

transportation charges on the disk. The central circle was a cloth disk with a dimension of 20 cm

in diameter.

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a

c

b

d

Figure S3. Material electrical tribo-polarity analysis for the chosen proper materials in DC-

DTENG. (a) All kinds of materials vs cloth, open-circuit voltage (Voc), and (b) all kinds of

materials vs cloth, transferred charges. (c) A selected extra positive material vs all kinds of

materials, Voc, and (d) a selected extra positive material vs all kinds of materials, transferred

charges.

Different kinds of dielectric materials had their tribo-polarity charges obtaining or losing

when they were facing against dissimilar material. The reason for a picked porous cloth

(Polyester) as a disk was its mechanical property, which was flexibility and easy integration into

a system as a rotator. Correspondingly, PVC (polyvinyl chloride) and PMMA (Poly(methyl

methacrylate)) were investigated as an ideal positive and negative dielectric materials in the view

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of porous cloth, respectively. It was noted that all the measurements here were obtained based on

the contact-separation mode. Here, the “leather” was man-made leather, and the rubber was

obtained from glove marked with “natural rubber”.

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a b

Figure S4. Electrical performance with different contact areas. (a) PVC vs cloth, and (b)

PMMA vs cloth.

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b

ElectrodeCloth

PMMA

c

a

PVC

I

II

III

To PMMA

To PVC

V

Figure S5. A separation-contact mode to demonstrate the porous cloth electrical property in

TENG, the triboelectric contact square area of porous cloth was 25 cm2. (a) Working principle of

a separation-contact mode, the porous cloth layer was doing a motion to contact with PMMA and

PVC, respectively. The gap between the PMMA and PVC film was filled with an air gap. (b) Voc,

cloth film vs PMMA and PVC, and c transferred charges, cloth film vs PMMA and PVC.

The top peaks in the curves meant the contacts between the porous cloth and the PMMA,

whereas the bottom peaks were the contacts between the porous cloth and the PVC. The flat line

in the curve meant separations of them. In an electrical system, if the positive peak here was

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defined as “1”, the flat line between them “0”, and the bottom peaks “-1”, then the output voltage

curve was modulated. The curves here presented a potential broaden application for a wave

modulation in an electrical system using TENG designed pattern.

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b c

ElectrodeCloth

PMMA

a

PVC

I II III

Figure S6. A sliding mode without any air gap between PMMA and PVC, the triboelectric

sliding area of porous cloth was 25 cm2. (a) Working principle of a sliding mode, the porous

cloth layer was doing a horizontal motion between PMMA and PVC, respectively, no air gap

between the PMMA and PVC film. (b) Voc, cloth film vs PMMA and PVC, and (c) transferred

charges, cloth film vs PMMA and PVC. We observed the negative state “1” and positive state “-

1”, and without any state “0”.

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c

f

a b

d e

Two “dielectric pairs” device

Coupling

Coupling

Eight “dielectric pairs” device

PMMAPVC

PVC

PMMA

Cloth

Cloth

Figure S7. A sliding mode without an air gap between PMMA and PVC. (a) The schematic

pattern of a sliding mode with two pairs dielectrics PMMA and PVC, scale bar 1 cm, the cloth

layer was doing a horizontal motion on the patterned structure among PMMA and PVC, no air

gap between the PMMA and PVC. (b) Voc, cloth film vs PMMA and PVC, and (c) transferred

charges, cloth film vs PMMA and PVC. (d) The schematic pattern of a sliding mode with eight

pairs dielectrics PMMA and PVC, scale bar 1 cm, the cloth layer was doing a horizontal motion

on the patterned structure among PMMA and PVC, no air gap between the PMMA and PVC. (e)

Voc, cloth film vs PMMA and PVC, and f transferred charges, cloth film vs PMMA and PVC. We

observed that the output voltage wave was modulated with those designed patterns in TENG.

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a b c

Figure S8. The output performance of DC-DTENG. (a-c) DC, Voc, and Qtac from the electrode

“B” with different motion states.

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a b c

Figure S9. Qtac in three kinds of DC-DTENG, (a) Electrode “A” vs ground, (b) Electrode “B” vs

ground, and (c) Electrode “A” vs ground, Qtac from a smaller dimension.

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Figure S10. The output voltage of DC-DTENG with various load resistors to demonstrate the

applied voltage on the external load resistors.

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Figure S11. The DC output voltage durability demonstration of DC-DTENG. It shows that the

DC-DTENG works well in a long period of operation. The rotational speed is ~60 rpm.

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Figure S12. Soft switch driven by DC-DTENG, the peak meant the contacts “on” state between

the soft copper tip and copper plate. It was observed that multiple contacts occurred in the

measurement for an actuator application.

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UV Light Lamb

a b

Figure S13. UV light radiation sensing application driven by DC-DTENG. (a) UV light

radiation lamb, scale bar 4 cm, and (b) a UV light radiation did influence the enhancement of DC

output based on our observation. The reason to explain was the photoelectric effect on the metal

surface of the electrode during the process of the charge releasing.

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b ca III

I

II

Figure S14. Charge abilities for 1 µF capacitor using electrode “A”, “B” and ground in DC-

DTENG. (a) Schematic charging electrical diagram using electrode “B” and “A”, (b) schematic

charging electrical diagram using electrode “B”, and (c) measurement voltage vs time on

capacitor for two connection methods.

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b ca

Figure S15. Two pairs of dielectrics DC-DTENG. (a) Schematic diagram of two pairs of

dielectrics DC-DTENG, scale bar 3 cm. (b) DC output from a pair of dielectrics and two pairs of

dielectrics. It was noted that a pair dielectric meant PMMA and PVC. (c) Qtac from a pair

dielectric and two pairs of dielectrics. The two pairs of dielectric materials resulted in 1.8 time’s

current output than a pair of dielectrics in our observation.

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Video S1. DC output and its clockwise, anticlockwise rotation performance of DC-DTENG.

Video S2. A soft switch was driven by an actuator.

Video S3. Bluetooth module wireless was driven by DC-DTENG for IoT sensor nodes.

Video S4. Status display in virtual reality (VR) by DC-DTENG for real-time monitoring.

Video S5. Continuous VR motion control by DC-DTENG for racing games.

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