Supporting Information

Minimalist and Multi-Functional Human Machine Interface (HMI) Using A

Flexible Wearable Triboelectric Patch

Qiongfeng Shia,b,c,d,1, Zixuan Zhanga,b,c,d,1, Tao Chene,**, and Chengkuo Leea,b,c,d,f,*

aDepartment of Electrical and Computer Engineering, National University of Singapore, 4

Engineering Drive 3, Singapore 117576, SingaporebCenter for Intelligent Sensors and MEMS, National University of Singapore, Block E6 #05-

11, 5 Engineering Drive 1, Singapore 117608, SingaporecHybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of

Singapore, Block E6 #05-3, 5 Engineering Drive 1, Singapore 117608, SingaporedNUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, P. R.

ChinaeJiangsu Provincial Key Laboratory of Advanced Robotics, School of Mechanical and Electric

Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology,

Soochow University, Suzhou 215123, P. R. ChinafNUS Graduate School for Integrative Science and Engineering, National University of

Singapore, Singapore 117456, Singapore1Both authors contributed equally to this work.

*Email: elelc@nus.edu.sg; **Email: chent@suda.edu.cn

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Table S1. Device dimensions of the triboelectric interacting patch.

Parameter Name Symbol Value

Individual electrode width w1 15 mm

Common electrode width w2 7 mm

Connection electrode width w3 5 mm

Electrode gap 1 g1 1 mm

Electrode gap 2 g2 1 mm

Diameter 1 d1 63 mm

Diameter 2 d2 93 mm

Diameter 3 d3 145 mm

2

Fig. S1. Output voltage signals generated from different operations. (a) The output

voltage of E1 when operating Point 1 with different manners (from top to bottom): 1)

tap on + vertical leave; 2) tap on + slide out; 3) slide on + vertical leave; 4) slide on +

slide out. (b) The output voltage of E1 and E2 when operating Point 2 with different

manners (from top to bottom): 1) tap on + vertical leave; 2) tap on + slide out; 3) slide

on +vertical leave; 4) slide on + slide out. The number in the figure indicates the peak

voltage value and the half maximum duration time of each peak. It can be observed

that positive peaks are generated when "tap on" or "slide on" a certain electrode point,

and then negative peaks are generated when "vertical leave" or "slide out" a certain

electrode point. Generally speaking, the generated peaks from "tap on" and "vertical

leave" motions have higher magnitude and shorter duration time than those from

"slide on" and "slide out" motions. It is also worth to note that for sliding motions on

common electrode points, continuous positive and negative peaks may be generated

from electrodes depending on the sliding directions.

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Table S2. The summarized ranges of voltage ratios of all the eight electrode points

from under tapping and sliding operations.

Voltage Ratios > 10 ~ 1 < 0.1

Point 1

V1/V2

V1/V3

V1/V4

Point 2

V1/V2

V1/V3

V1/V4

Point 3

V1/V2

V1/V3

V1/V4

Point 4

V1/V2

V1/V3

V1/V4

Point 5

V1/V2

V1/V3

V1/V4

Point 6

V1/V2

V1/V3

V1/V4

Point 7

V1/V2

V1/V3

V1/V4

Point 8

V1/V2

V1/V3

V1/V4

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Fig. S2. Output voltages of the eight electrode points recorded after analog-to-digital

converter (ADC). (a) Schematic diagram for tapping on the eight electrode points. (b)

Output voltage waveforms from the four electrodes. (c) The corresponding output

voltage ratios of V1/V2, V1/V3, and V1/V4. (d) Schematic diagram for sliding on the

eight electrode points. (e) Output voltage waveforms from the four electrodes. (f) The

corresponding output voltage ratios of V1/V2, V1/V3, and V1/V4.

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Fig. S3. Operations on the device with one electrode point involved. (a-c) Schematic

diagram and the output voltages from the operations (tapping + sliding + leaving)

between Point M and Point 5, and Point M and Point 6. (d-f) Schematic diagram and

the output voltages from the operations between Point 5 and Point A5, and Point 6 and

Point A6.

First, operations between Point M and the electrode points (Point 5 and 6 as

examples) are investigated, together with the corresponding signal waveforms shown

in Fig. S3(a) to (c). When finger first contacts Point M, positive voltage peaks with

small magnitude are generated on all the four electrodes due to the coupling of small

amount of triboelectric charges on electrode. Then when finger slides on Point 5 (or

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Point 6), a large positive peak is (or two large positive peaks are) generated on E3 (or

E3 and E4) due to the direct coupling of large amount of triboelectric charges. If

finger stops sliding and stays on the electrode point, no output peak is generated for

that period. The moment when finger leaves the device from Point 5 (or Point 6), a

large negative peak is (or two large negative peaks are) generated on E3 (or E3 and

E4). For the sliding operation in the opposite direction (i.e., from the electrode points

to Point M), output voltage peaks with similar magnitude but opposite polarity are

generated in a reverse manner. Fig. S3(d) to (f) show the output characteristics from

the operations between electrode points and outer points. When finger first contacts

the device from Point 5 (or Point 6), a large positive peak is (or two large positive

peaks are) generated on E3 (or E3 and E4). Then when finger slides out of the

electrode area, negative peaks are generated on the corresponding electrodes. It is

worth to note that for E4 as in Fig. 5(i), positive peak is first generated before the

negative peak under this operation. This is because that when finger slides from Point

6 toward outside, the covering area of E4 by finger is actually increasing first before

decreasing. Next, when finger continues to slide and stop on the outer point, no output

peak is generated during this period. The moment when finger leaves the device from

Point A5 (or Point A6), a small negative peak is (or two small negative peaks are)

generated on E3 (or E3 and E4). Similar output peaks with opposite polarity and

reverse order are generated for the opposite direction.

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Fig. S4. Operations on the device with two electrode points involved. (a-c) Schematic

diagram and the output voltages from the operations between Point A7 and Point 3,

and Point A6 and Point 2. (d-f) Schematic diagram and the output voltages from the

operations between Point 7 and Point 3, and Point 6 and Point 2.

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Fig. S5. Operations on the device around the electrode points. (a) Schematic diagram

and (b) the output voltages from the operations between Point 2 and Point 8. (c)

Schematic diagram and (d) the output voltages for the operations circling around all

the electrode points starting from Point 2.

As shown in Fig. S5(a) and (b), when finger first contacts the device on Point 2, large

positive peaks are generated on both E1 and E2. Then when finger slides to from

Point 2 to Point 1, small positive peak is generated from E1 and small negative peak

is generated from E2. Next, when finger slides to Point 8, small negative peak is

generated from E1 and small positive peak is generated from E4. Last, when finger

leaves the device from Point 8, large negative peaks are generated on both E1 and E4.

Similar phenomenon can be observed for circling operation starting from Point 2 as

indicated in Fig. S5(c) and (d).

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Fig. S6. Output voltage waveforms from tapping motions on the sixteen sections for

identification code system.

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Fig. S7. Block diagram of the processing circuit and connection.

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Fig. S8. The output voltages from tapping motions to control the vehicle to (a) go

forward, (b) go right front, (c) turn right, (d) go right rear, (e) go backward, (f) go left

rear, (g) turn left, and (h) go left front.

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Supporting Videos.

Video S1. Demonstration of writing characters of “N”, “U” and “S”.

Video S2. Demonstration of real-time control of a wireless vehicle.

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