. 2020 Aug 7;20(16):4407. doi: 10.3390/s20164407

Table A2.

Features of state-of-the-art pressure sensors based on capacitance (C), piezoelectricity (PE), piezoresistivity (PR), and triboelectricity (TE). “Stability” is the number of loading (L), stretching (S), or bending (B) cycles the sensor was subjected. Symbols: Inline graphic —Breathing; —Functional Prosthesis; —Health Monitoring; —Human Machine Interfaces; —Muscle Movements; —Pressure Mapping; ♡—Pulse wave pressure at the wrist/neck/arm/ankle/head or heart rate; —Robots; —Sound monitoring; —Speech; —Temperature Mapping or Monitoring; Inline graphic —Vibration Monitoring; Health Monitoring; —Walking. Abbreviations and acronyms: Ag—Silver; Al—Aluminum; AR—Aspect Ratio; Au—Gold; B—Bending; CNTs—Carbon Nanotubes; Cu—Copper; elec.—Electrode(s); Electrospin.—Electrospinning; FEP—Fluorinated Ethylene Propylene; IL—Ionic Liquid; ITO—Indium Tin Oxide; L—Loading; LOD—Limit of Detection; MOSFET—Silicon Metal Oxide Semiconductor Field Effect Transistor; MWCNTs—Multi-walled Carbon Nanotubes; Ni—Nickel; NPs—Nanoparticles; NRs—Nanorods; NWs—Nanowires; OFET—Organic Field-Effect Transistor; OTFT—Organic Thin Film Transistor; P(VDF-HFP)—Poly(vinylidene fluorideco-hexafluoropropene); P(VDF-TrFE)—Poly(vinylidenefluoride-co-trifluoroethylene); PANI—Polyaniline; PDMS—Polydimethylsiloxane; PEDOT:PSS—Poly(3,4-ethylenedioxythiophene)–Poly(styrenesulfonate); PEN—Polyethylene Naphthalene; PET—Polyethylene terephthalate; Photolit.—Photolithography; PI—Polyimide; PLLA—Poly(L-lactide); PMMA—Poly(methyl methacrylate); PPy—Polypyrrole; PS—Polystyrene; Pt—Platinum; PTFE—Polytetrafluoroethylene; PU—Polyurethane; PUD—Polyurethane Dispersion; PVA—Polyvinyl Alcohol; PVDF—Poly(vinylidene fluoride); PVP—Poly(4-vinylphenol); PZT—Lead Zirconate Titanate; Rel.—Relaxation; Res.—Response; rGO—reduced Graphene Oxide; S—Stretching; SWCNTs—Single-walled Carbon Nanotubes; Ti—Titanium; TPU—Thermoplastic Urethane Polymer; ZnO—Zinc Oxide.

Type of Sensor	Group, Year	Description	Micro-Structuring Technique	Sensitivity (kPa⁻¹), Range of Pressures (kPa)	LOD/Maximum Pressure Tested	Res./Rel. Times (ms)	Stability	Operating Voltage/Energy Consumption	Application
C	Z. Bao [24] 2010	OFET, whose dielectric layer is PDMS with micro-pyramids (6 µm of width).	Photolit.	0.55 (0–2)	3 Pa/ 40 kPa	<300/ <500	10⁴ (L) 15,000 (B)	- 20 V/-
C	Z. Bao [84] 2011	Ecoflex, and elec. of SWCNTs on PDMS.	-	2.23 × 10⁻⁴ (50–1000)	50 kPa/ 1 MPa	<125/ <125	4 (L) 4 (S)	-/-
C	Z. Bao [30] 2013	OTFT, whose dielectric layer is PDMS with triangular lines (7 µm of width, 7 µm of height).	Photolit.	8.2 (0–8) 0.38 (8–50)	~ 200 Pa/ 56 kPa	<1/<10	15,000 (L)	- 100 V/1 mW	(♡)
C	D. Zhu [276] 2015	Flexible suspended gate OTFT.	-	192 (0.1–5)	0.3 Pa/ 5 kPa	<10/<10	10⁵ (L)	- 60 V/<1 mW	(♡)
C	Y. Hong [75] 2015	PMMA or PVP, and elec. of PDMS micro-structures (6 µm of height) coated with Ag NWs, and Ag on arylite.	UV/O₃ treatment	3.8 (0.045–0.5) 0.8 (0.5–2.5) 0.35 (2.5–4.5)	45 Pa/ 10 kPa	<150/ <150	1500 (L) 5000 (B)	0.1 V/-
C	Z. Bao [165] 2015	PDMS pyramids (6 µm of width, 3 µm of height), PDMS microhairs (30 µm of diameter, AR of 3, 6, and 10), and elec. of PEN and Au.	Photolit.	0.55–0.58 (0–1)	~ 100 Pa/ 10 kPa	-/<30	3000 (L)	1 V/-	(♡)
C	S. P. Lacour [36] 2015	Porous silicone foam with Au elec.	Foam	1 × 10⁻²–1 × 10⁻³ (5–405)	2 kPa/ 405 kPa	7/14	250,000 (L)	-/-
C	S.-D. Lee [72] 2016	Porous PDMS between glass or PET, and ITO elec.	Water mixing and heat	1.18 (0–0.02)	20 Pa/ 5 kPa	150/150	-	-/-
C	P. Zhu [82] 2017	PVDF dielectric layer, PDMS waves (2.6 µm of width, 800 nm of height), with Ag NWs as elec.	Stretching and plasma treatment	2.94 ± 0.25 (0–2) 0.75 ± 0.06 (2–6.7)	3 Pa/ 6.7 kPa	<50/<50	10³ (L) 10³ (B)	-/-	()
C	C. F. Guo [43] 2018	Ionic gel [P(VDF-HFP) and IL] micro-cones (25 µm of height), with elec. of Ag NWs on PI.	Leaf as mold	54.31 (0–0.5) 30.11 (0.5–10) 8.42 (10–40) 1.03 (40–115)	0.1 Pa/ 115 kPa	29/37	5400 (L)	-/-	()
C	C. F. Guo [173] 2018	PDMS micro-towers (6.5 µm of diameter, 14 µm of height) covered with Ag NWs, and Ag NWs on PI.	Lotus leave as mold	1.194 (0–2) 0.077 (2–13)	0.8 Pa/ 13 kPa	36/58	10⁵ (L)	-/-	()
C	Z. L. Wang [273] 2018	Ecoflex, and Ag elec.	-	0.0224 (0–16) 1.25 × 10⁻³ (16–360)	7.3 Pa/ 360 kPa	-/-	-	-/-
C	C. F. Guo [277] 2018	Rose petal or leaf, or Acacia Mill leaf, with elec. of Ag NWs on PI.	Rose petals and plants leaves	1.54 (0–1) 0.068 (1–40) 0.014 (40–115)	0.6 Pa/ 115 kPa	-/-	5000 (L) 5000 (B)	-/-	()
C	V. Palaniappan [251] 2019	PDMS micro-pyramids, with elec. of Ag on PET, in interlocked design.	Laser engraved mold	2.2 × 10⁻³ (0.075–0.17)	75 Pa/ 170 Pa	-/-	-	-/-	(♡)
C	G. Xing [199] 2019	Polyurethane sponge covered with a composite of silicone rubber, MWCNTs, and graphene nanoplates.	Sponge	0.062 (0–0.3) 0.033 (0.3–4.5)	3 Pa/ 4.5 kPa	45/83	2000 (L)	-/-	(♡ )
C	J. Y. Park [33] 2019	Ionic gel [P(VDF-HFP) and IL] micro-structures (26 µm of size), with elec. of Ag NWs on PDMS.	Sandpaper as mold	131.5 (0–1.5) 11.73 (5–28)	1.12 Pa/ 32 kPa	43/71	7000 (L)	0.5 V/-	(♡)
C	R.-W. Li [86] 2020	Micro-needles (diameter between 166 µm and 422 µm, height between 275 µm and 856 µm) of PDMS and Ni-coated magnetic particles of Ag.	Self-assembly	0.159 (0–1) 0.019 (1.5–11) 4.1 × 10⁻³ (12–145)	1.9 Pa/ 145 kPa	49/51	9200 (L)	-/-	()
C	C. F. Guo [171] 2020	Iontronic protrusions, and elec. of Au on PI.	Sandpaper as mold	3302.9 (0–10) 671.7 (10–100) 229.9 (100–360)	0.08 Pa/ 360 kPa	9/18	5000 (L) 2000 (B)	-/-	(♡)
C	M. Zhang [278] 2020	Parylene with elec. of Au-coated PDMS micro-pyramids (35 µm of width, 24.7 µm of height) and ITO on PET.	Photolit.	70.6 (0–0.05) 3.3 (0.05–0.325)	1 Pa/ 325 Pa	-/-	10,200 (L)	-/-	(♡)
C	T. Lee [177] 2020	PDMS hierarchical interlocked micro-structures, with elec. of ITO on PET.	Rose petals as mold	0.055 (2–10)	-/10 kPa	300/250	-	1 V/-	(♡)
C or PR	S. Park [85] 2019	Porous PDMS micro-pyramids (50 µm of width), with elec. of ITO on PET (for C sensor), or covered with PPy, with patterned elec. (for PR sensor).	Photolit.	44.5 (0–0.1) (C) 449 (0–0.01) (PR)	0.14 Pa/ 35 kPa (C) or 600 Pa (PR)	50/100 (C) 9/30 (PR)	5000 (L) (C)	1 V/- (C, PR)	(♡)
PE	J. A. Rogers [104] 2013	Aligned fiber of P(VDF-TrFE).	Electrospin.	0.79 V kPa⁻¹ (0–0.012) 1.1 V kPa⁻¹ (0.4–2)	0.1 Pa/ 2 kPa	-/-	10³ (B)	-/-
PE	J. A. Rogers [90] 2014	Array of PZT squares connected to the gate elec. of a MOSFET.	-	2 µA Pa⁻¹ (0.002–0.01)	0.005 Pa/ 10 Pa	0.1/-	10³ (L)	-/-	(♡)
PE	N.-E. Lee [106] 2015	OFET array with P(VDF-TrFE) micro-pyramids (4 µm of width, 2.5 µm of height) as gate dielectric.	Photolit.	1.016 (0.02–0.08) 0.028 (10–100)	20 Pa/ 20 kPa	20/-	10⁴ (B)	-/10 µW	(♡)
PE	K. J. Lee [89] 2017	PZT thin film on PET, with elec. of Au.	-	0.018 (1–30)	1 kPa/ 60 kPa	60/-	5 000 (L)	-/-	(♡)
PE	Q.-L. Zhao [91] 2017	PZT NWs on planar interdigitated Pt/Ti elec.	-	0.14 V kPa⁻¹ (15–70)	15 kPa/ 70 kPa	-/-	10⁵ (L)	-/-	-
PE	D. Mandal [279] 2017	Fish gelatin nanofibers.	Electrospin.	0.8 V kPa⁻¹ (0.3–10)	2 Pa/ 25 kPa	16/-	108,000 (L)	-/-	(♡)
PE	D. Mandal [272] 2017	Electrospun PLLA nanofibers.	Electrospin.	3 V kPa⁻¹	18 Pa/ 300 kPa	-/-	375,000 (L)	-/-	(♡)
PR	K.-Y. Suh [131] 2012	Interlocked array of PU nanohairs (50 nm of diameter, 1 µm of height) coated with Pt.	Photolit.	-	5 Pa/ 1.5 kPa	50/-	8000 (L)	-/-	(♡)
PR	J.-J. Park [125] 2014	PDMS micro-pyramids (8 µm of width, 4 µm of height) covered with PEDOT:PSS/PUD.	Photolit.	4.88 (0.37–5.9)	23 Pa/ 8 kPa	200/200	800 (S)	0.2 V/-	(♡)
PR	X. Chen [126] 2014	PDMS micro-pyramids (4.5 µm of width) covered with rGO and elec. of ITO on PET.	Photolit.	−5.5 (0–0.1) −0.01 (0.1–1.5)	1.5 Pa/ 1.5 kPa	0.2/-	5000 (L)	1 V/-	-
PR	W. Cheng [38] 2014	PDMS microdomains (18 µm of diameter, 16 µm of height) covered with Au.	Mimosa leaves as mold	50.17 (0–0.07) 1.38 (0.2–1.5) 0.04 (2–10)	10.4 Pa/ 10 kPa	20/-	10⁴ (L) 5000 (B)	0.1 V/-
PR	W. Cheng [217] 2014	Interdigitated elec. on PDMS sheet with Au NWs coated tissue paper.	Fabric	1.14 (0–5)	13 Pa/ 5 kPa	-/17	50,000 (L) 5000 (B)	1.5 V/30 µW	(♡)
PR	X. Chen [127] 2014	Silicon micropillars (20 µm of diameter, 17 µm of height) covered with Au, and a PPy film on PDMS.	Photolit.	−1.8 (0–0.35)	2 Pa/ 10 kPa	<100/ <100	-	-/-	-
PR	D.-H. Kim [42] 2014	Porous MWCNTs@PDMS with elec. of conductive carbon fabric.	Reverse micelles	-	250 Pa/ 260 kPa	-/-	16 (L)	0.1 V/1 W
PR	Z. Bao [41] 2014	ITO on PET and Cu foil as elec. and interconnected hollow-sphere structures of PPy hydrogel micro-structured into triangular lines (0.5 mm in height, 1 mm of width).	Photolit.	56–133.1 (0–0.030)	0.8 Pa/ 10 kPa	50/50	8000 (L)	-/-
PR	D.-H. Kim [35] 2014	Single crystalline silicon nanoribbon with linear or serpentine shapes.	-	4.1 × 10⁻³ (0–200)	-/200 kPa	-/-	-	-/-
PR	H. Ko [133] 2014	Interlocked array of MWCNTs@PDMS microdomes (4 µm of diameter, 3 µm of height).	Photolit.	−15.1 (0–0.5)	0.23 Pa/ 59 kPa	40/40	10³ (L)	10 V/-	()
PR	H. Ko [132] 2014	Interlocked array of MWCNTs@PDMS micropillars (5 µm of diameter, 6 µm of height) with Cu elec.	Photolit.	−22.8 (0–0.05)	10 Pa/ 17 kPa	110/130	-	10 V/-
PR	T. Zhang [179] 2014	PDMS with micro-structures (11 µm of width, 3.2 µm of height) covered with SWCNTs.	Silk as mold	1.8 (0–0.3)	0.6 Pa/ 1 kPa	10/-	67,500 (L)	2 V/-	(♡)
PR	T.-L. Ren [280] 2015	Carbon black@rubber micro-structures (17 µm of height) with Cu elec.	Abrasive grains as mold	13.8 (0–14.5)	<1 kPa/ 14 kPa	23/-	400 (L)	-/-	-
PR	J. S. Ha [31] 2015	PDMS micropillars (50 µm of diameter, 48 µm of height) covered with Au, and PANI fibers on PET.	Photolit.	2 (0–0.22) 0.87 (0.22–1)	15 Pa/ 9 kPa	50/-	10⁴ (L)	1 V/-	(♡)
PR	T.-L. Ren [274] 2015	Two interlocked films of graphene micro-structures (20 µm of width, 11 µm of height).	DVD laser-scribing	0.96 (0–50) 5 × 10⁻³ (50–113)	-/113 kPa	72/0.4	10² (L)	-/-
PR	R. Jelinek [193] 2015	Au-coated amine-functionalized PU sponge with Cu elec.	Sponge	−0.31 (0–2) −0.02 (2–10)	10 Pa/ 10 kPa	8/-	10³ (L)	-/-	(♡)
PR	K. Cho [139] 2016	PDMS hierarchical micro-domes (59 µm of diameter) with interdigitated graphene elec.	Photolit.	8.5 (0–12)	1 Pa/ 12 kPa	40/30	10⁴ (L)	1 V/-	(♡)
PR	N. Zhao [32] 2016	Nonwoven wood pulp/polyester textile with carbon black particles, and elec. of Au on PI.	Fabric	0.585 (0–35)	-/35 kPa	4/4	5800 (L)	1 mV/3 nW	(♡)
PR	T. Liu [275] 2016	Graphitic structures in PI.	Direct laser writing	-	-/-	-/-	10⁴ (L)	-/-	(♡)
PR	Y.-F. Chen [271] 2016	Ag NWs@PDMS, and conductive threads as bottom elec. in a cloth substrate.	-	1.04 × 10⁴–9.3 × 10⁵ (0–0.1) 2.72 × 10⁶–6.57 × 10⁶ (0.38–3)	0.6 Pa/ 5 kPa	4/16	5000 (L)	0.1 V/-	()
PR	H. Zhang [232] 2017	PDMS sponge covered with CNTs, with elec. of ITO on PET.	Cube sugar as template	0.03 (0–15) 4.8 × 10⁻³ (25–50)	26 Pa/ 150 kPa	300/100	2000 (L)	2 V/-	(♡)
PR	B. Yu [19] 2017	PDMS micro-pyramids (10 µm of width, height) covered with MWCNTs, and elec. of Au/Ni on PET.	Photolit.	−9.95 (0–0.1) −1.5 × 10⁻² (0.175–0.6)	20 Pa/ 600 Pa	<200/-	20 (L)	1 V/-	-
PR	Y. Lin [129] 2017	PDMS micro-pyramids (11 µm of width, 7.4 µm of height) covered with SWCNTs, and elec. of ITO on PET.	Photolit.	2760 (0–0.4) 8656 (0.4–0.9) 1875 (0.9–1.2)	7.3 Pa/ 1.2 kPa	<4/-	10⁴ (L)	30 V/26.4 nW	(♡)
PR	N.-J. Cho [140] 2017	MWCNTs@PDMS@Sunflower pollen microcapsules, film of PDMS with micro-cubes (150 µm of width), and Cu elec.	Nylon mesh as mold	56.36 (0–1) 2.51 (2–10)	1.6 Pa/ 10 kPa	500/300	25,000 (L)	-/-	(♡)
PR	S. Jeon [161] 2017	PDMS micro-pyramids (20 µm of width) covered with PEDOT:PSS/PUD + Ag NPs.	Photolit.	2.5 (0–0.25)	3 Pa/5 kPa	20/20	10⁵ (L)	0.5 mV/-	(♡)
PR	M. Khine [183] 2017	Interlocked design of PDMS films covered with wrinkled CNT film.	Heat and shrinking	278.5 (0–0.002) 13.2 (0.002–0.025)	0.5 Pa/ 12 kPa	<20/-	500 (L)	1 V/-	(♡)
PR	Z. Tang [189] 2017	Wrinkled graphene films separated by a layer of porous anodic Al oxide.	Chemical synthesis	6.92 (0.3–1.5) 0.14 (1.5–4.5)	300 Pa/ 8 kPa	-/-	10⁵ (L)	1 V/-	-
PR	G. Shen [239] 2017	Film of PANI hollow nanospheres (≈ 414 µm of diameter), MWCNTs, and PVDF, sandwiched between elec. of Au on PDMS.	PS spheres as template	31.6 (0–0.25) 10.61 (1–7)	0.6 Pa/ 50 kPa	100/150	15,000 (L)	1 V/-	(♡)
PR	N. Zhao [281] 2017	Fibers of nylon covered with Cu and doped with carbon black particles and PVDF, with interdigitated elec. of Au on PI.	Nylon fibers	≈ 1 (0–70)	-/60 kPa	2/2	22,000 (L)	1 V/-	(♡)
PR	J. Sun [270] 2017	PDMS mountain (220 µm of width, 30 µm of height) with secondary (35 µm of width, 12 µm of height) and tertiary ridges, and Ag elec.	Banana leave as mold	10 (0–0.4) 3.3 (0.4–1) 0.33 (1–7)	1 Pa/7 kPa	36/30	10⁴ (L)	-/-	(♡)
PR	R. Igreja [22] 2018	PDMS micro-cones (221 µm to 367 µm of diameter, 299 µm to 552 µm of height) covered with carbon coating.	Laser engraving	−2.52 (0–0.16) −0.2 (0.2–1.2) −0.01 (1.6–9)	15 Pa/ 9 kPa	20/-	-	1 V/-	(♡)
PR	T. Zhang [156] 2018	Micro-pyramids (≈ 20 µm of width) of PDMS covered with SWCNTs with a substrate of PEN.	Photolit.	−3.26 (0–0.3) −0.025 (0.6–2.5)	-/2.5 kPa	200/100	5000 (L)	10 V/-	(♡)
PR	H. Ko [136] 2018	MWCNTs@PDMS interlocked micro-domes, micro-pyramids, or micro-pillars (10 µm of diameter/width, 6 µm of height), with Cu elec.	Photolit.	47 × 10³ (0–1) 90 × 10³ (1–10) 30 × 10³ (10–26) (Micro-domes)	0.09 Pa/ 26 kPa	12/12	10³ (L)	0.1 V/-	(♡)
PR	W. Yang [39] 2018	Two micro-structured PDMS films covered with Ag NWs in an interlocked design.	Emery paper as mold	9.8 × 10⁴ (0–0.2) 3.5 × 10³ (0.2–20)	5 Pa/ 20 kPa	<62.5/ <62.5	10³ (L)	0.1 V/1.5 nW	()
PR	J. Yao [190] 2018	ZnO NWs sea-urchin like aggregates, between elec. of ITO on PET.	Chemical synthesis	75–121 (0–0.2) >15 (0.2–10)	0.015 Pa/ 10 kPa	7/9	2000 (L)	5 V/-	(♡)
PR	Y. Gao [205] 2018	Carbonized melamine foam.	Foam	100.29 (0.003–2) 21.22 (2–10)	3 Pa/ 10 kPa	-/-	11,000 (L)	0.1 V/ -	(♡)
PR	S. J. Oh [191] 2018	Conductive Ag nanocrystals on a PDMS film with triangular lines (1 mm of width, 0.5 mm of height), with spacers of insulating Ag nanocrystals.	Self-assembly	2.72 × 10⁴ (0–5) 4.70 × 10³ (5–20) 1.09 × 10² (20–100)	10 Pa/ 100 kPa	200/50	200 (L)	0.001 V/ <100 nW	(♡)
PR	X. Peng [229] 2018	Carbon aerogel with cellulose nanocrystals with elec. of Ni on PET.	Freeze-drying	103.5 (0–0.01) 27.5 (0.01–18)	1 Pa/ 18 kPa	-/-	50,000 (L)	1 V/-	(♡)
PR	Y. Fan [282] 2018	Carbonized lignin@PDMS.	-	57 (0–2)	500 Pa/ 130 kPa	60/40	10⁵ (L)	1 V/-	(♡)
PR	S. Shiratori [143] 2018	Two PDMS films micro-structured into fish-scales (0.62 µm of height), covered with PEDOT:PSS and graphene nanosheets, facing each other.	Surface tension	−70.86 (0–1) −1.15 (2–5)	100 Pa/ 5 kPa	82.6/-	-	-/-	(♡)
PR	Y.-J. Yang [181] 2018	MWCNTs@PDMS interlocked micro-domes (3 µm of diameter), with Au elec.	Nylon membrane filter as mold	−6.08 (0–0.15)	-/8.5 kPa	-/-	10⁴ (L)	-/-	(♡)
PR	F. Xuan [37] 2018	Triangular lines of PDMS (10 µm to 14 µm of width, 28 µm to 39 µm of height) covered with CNTs as bottom elec., and smooth PDMS covered with CNTs as top elec.	Laser engraving	−0.11 (0.005–2) −1.28 × 10⁻³ (10–50)	5 Pa/ 50 kPa	200/150	10⁴ (L)	1 V/-	(♡)
PR	L. Li [283] 2018	Pyramid-like structures (4 µm of height) of MWCNTs@PDMS, with an elec. of Au and other of ITO on PET.	Silicon as mold	474 (0–0.4) 14.7 (0.4–1.4) 8.4 (5–110)	0.6 Pa/ 110 kPa	0.002/ 0.074	10³ (L)	1 V–5 V/-	(♡)
PR	N. Liu [284] 2018	NWs of PVA sandwiched between interdigitated elec. of Ag/Ni and a wrinkled rGO film.	-	4.52 (0–3) 28.34 (3–10)	2.24 Pa/ 14 kPa	87–155/-	6000 (L)	0.1 V/-	(♡)
PR	L. Li [285] 2018	Micro-pyramids of PDMS covered with PPy, with co-planar Au elec.	Photolit.	1907.2 (0–0.1) 461.5 (0.1–1) 230.1 (1–1.9)	0.08 Pa/ 1.9 kPa	0.05/6.2	15,000 (L)	1 V/-	(♡)
PR	J. Li [195] 2018	Sea sponges with polydopamine, rGO, and Ag NWs.	Sponge	0.016 (0–40)	0.28 Pa/ 40 kPa	-/54	7000 (L)	-/-	()
PR	T.-L. Ren [168] 2018	Micro-structures of PDMS coated with rGO, in interlocked geometry.	Sandpaper as mold	25.1 (0–2.6) 0.45 (10–40)	16 Pa/ 40 kPa	120/80	3000 (L)	-/-	(♡)
PR	R. Igreja [247] 2019	PDMS semi-spheres (320 µm to 340 µm of diameter, 105 µm to 155 µm of height) coated with carbon coating.	Laser engraving	−0.18 (0–0.4) −6.4 × 10⁻³ (1.2–100)	79 Pa/ 100 kPa	-/28	27,500 (L)	5 V–10 V/-
PR	W. Lu [182] 2019	Micro-structured PDMS covered with graphene, with interdigitated elec. of Ni/Au.	Silk as mold	1875.5 (0–20) 853.2 (20–40)	1.8 Pa/ 40 kPa	2/3	15,000 (L)	1 V/-	(♡)
PR	X. Wang [286] 2019	PDMS with graphene protrusions.	Laser scribing	480 (0–0.1) 34 (0.1–0.4) 0.9 (0.4–1)	28 Pa/ 1 kPa	0.002/ 0.002	4000 (L)	5 V/160 µW	(♡)
PR	D. Zeng [130] 2019	PDMS micro-structures (250 µm, 60 µm, or 15 µm as average height) covered with rGO, with elec. of Au on PI.	Sandpaper as mold	2.5 (0–1) 12 (1–50) 1051 (50–200)470 (200–400)	10 Pa/ 400 kPa	150/40	10⁴ (L)	1 V/-	(♡)
PR	V. Roy [170] 2019	Micro-structured foam (top and bottom sides) of PDMS and graphite, with elec. of ITO on PET.	Sandpaper as mold	245 (0–120) 90 (120–150)	5 Pa/ 150 kPa	8/4	25,000 (L)	-/-	(♡)
PR	Z. Peng [144] 2019	Porous matrix of TPU@NaCl@carbon black particles, with elec. of TPU@Ag particles.	3D printed mold	5.54 (0–10) 0.123 (10–100) 4.8 × 10⁻³ (100–800)	10 Pa/ 800 kPa	20/30	10⁴ (L)	0.3 V/-	(♡)
PR	C. Yang [287] 2019	Au-coated PDMS conical frustum-like structures, with interdigitated elec. of SnSe₂ nanoplates covered with Au.	Photolit.	433.22 (0–2.4) 2.91 (5–40)	0.82 Pa/ 40 kPa	0.07/0.09	4000 (L)	-/-	(♡)
PR	F. Xuan [250] 2019	PDMS long or short micro-ridges (19.1 µm of width, 20.2 µm of height, 1 mm or 100.5 µm of length), or micro-domes (22.8 µm of diameter, 19.5 µm of height) covered with CNTs.	Laser engraving	−1.82 (0–2) −9.1 × 10⁻⁴ (10–80)	1 Pa/ 80 kPa	36/52	6000 (L)	-/-	(♡)
PR	W. Huang [212] 2019	Ag interdigitated elec. on cellulose paper, and porous tissue paper coated with Ag NWs.	Tissue paper	1.5 (0.03–30)	30 Pa/ 30 kPa	90/90	-	0.1 V/10 nW	(♡)
PR	Y. Tian [288] 2019	PDMS micro-pillars (500 µm of diameter, 200 µm of height) covered with Ag NWs in interlocked array.	Photolit.	20.08 (0.05–0.8) 3.81 (0.8–2.1)	20 Pa/ 8 kPa	-/-	10⁴ (L)	1 V/-	()
PR	C. Pang [164] 2019	PDMS film with micro-pillars on top (30 µm of diameter, 15 µm or 30 µm of height) and hexagonal structures on bottom (200 µm of width, AR of 1.5), and elec. of graphene on PDMS.	Photolit.	0.015 (0–8) 2 × 10⁻⁴ (8–20)	20 Pa/ 370 kPa	11/5	10³ (L)	-/-	-
PR	B. Zhou [252] 2019	PDMS micro-domes (1000 µm of diameter) with hierarchical pillars (50 µm of diameter), covered with Ag NWs, in interlocked geometry.	Laser cutting and Photolit.	374.5 (0–0.3) 3.86 (0.3–20) 0.63 (20–80)	2.5 Pa/ 80 kPa	-/-	10⁴ (L)	1 V/-	(♡)
PR	P. Liu [244] 2020	NaOH modified tissue paper with silicon rubber, carbon black, and graphene nanoplates as active layer, silicon rubber micro-domes, and interdigitated elec. of Au on PI.	3D printed mold and tissue paper	37.5 (0–2) 2.75 (2–10)	5 Pa/ 10 kPa	50/30	3000 (L)	-/-	(♡)
PR	T. Zhang [253] 2020	PDMS semi-spheres (280 µm of diameter, 200 µm of height) with micro-structures covered with rGO, with interdigitated elec. of Ag NWs.	Laser engraving	15.4 (0–200)	16 Pa/ 300 kPa	15/20	7500 (L)	1 V/-	(♡)
PR & PE	H. Ko [87] 2015	Interlocked array of PDMS micropillars (10 µm of diameter, 10 µm of height) covered with ZnO NWs (coated with Pt or Ni).	Photolit.	−6.8 (0–0.3) −1 × 10⁻² (0.3–4.6) −6.78 × 10⁻⁵ (4.6–13.1)	0.6 Pa/ 13 kPa	5/-	10³ (L)	10 V/-
PR & PE	H. Ko [88] 2015	Interlocked array of rGO@PVDF microdomes (10 µm of diameter, 4 µm of height).	Photolit.	-	0.6 Pa/ 49.5 kPa	-/-	5000 (L)	-/-	(♡)
PR & PE	J. Jang [99] 2016	ZnO NRs covered with PVDF, and elec. of rGO.	Chemical synthesis	-	4 Pa/20 Pa	120/-	10³ (L)	-/-	(♡)
TE	Z. L. Wang [150] 2013	PDMS film with micro-pyramids (10 µm of width), with an elec. of Au and another elec. of Al with Ag NWs and NPs.	Photolit.	0.31 (0–3) 0.01 (3–12)	2.1 Pa/ 12 kPa	<5/<5	30,000 (L)	-/-
TE	Z. L. Wang [153] 2016	PET film, a micro-structured PDMS film, and Ag elec.	Dry etching	0.06 (1–80)	1 kPa/ 200 kPa	70/-	10⁴ (L)	-/-
TE	L. Wang [269] 2016	Rough PET (40 µm of dimension, 0.8 µm of depth) coated with Al, and elec. of Al on PTFE.	Chemical etching	-	-	1/-	-	-/-	(♡)
TE	Z. L. Wang [154] 2017	PDMS film with micro-pyramids (80 µm of width), Ag elec., and SiO₂ as insulator.	Photolit.	6 × 10⁻³ (0–40)	600 Pa/ 200 kPa	50/-	-	-/-
TE	S.-W. Kim [289] 2017	Transistor with an ion-gel gate dielectric.	-	0.02 (0–10)	<1 kPa/ 57 kPa	30/-	1700 (L)	0.5 V/180 µW
TE	Y. Zhang [290] 2017	PDMS film with elec. of carbon fiber.	-	0.055 nA kPa⁻¹ (28.2–41.6)	800 Pa/ 41.6 kPa	68/-	10⁴ (L)	-/-
TE	Z. L. Wang [291] 2017	PDMS or VHB, and hydrogel of polyacrylamide with LiCl as elec.	-	0.013 (1.3–70)	1.3 kPa/ 100 kPa	-/-	20,000 (L) 10³ (S)	-/-
TE	Z. L. Wang [20] 2018	Silk, nylon, and an elec. of CNTs.	Fabric	0.0479 (0–125) 0.0186 (125–350) 0.0033 (350–650)	-/650 kPa	-/-	10⁴ (L)	-/-
TE	H. Ko [147] 2018	P(VDF-TrFE) and PDMS films with interlocked semi-spheres (100 µm of diameter, 120 µm of height).	Photolit.	0.55 V kPa⁻¹ (0–19.8) 0.2 V kPa⁻¹ (19.8–98)	-/98 kPa	-/-	10⁴ (L)	-/-	(♡)
TE	Z. L. Wang [40] 2018	Ecoflex with triangular microprisms (1.24 mm of width, 1.64 mm of height), with an elec. of Ag flakes on ecoflex.	Laser grinding machine	0.29 (0–5) 0.005 (5–25)	63 Pa/ 320 kPa	-/-	10³ (L)	-/-	(♡)
TE	Z. L. Wang [265] 2018	PTFE strips with NWs (110 nm of diameter, 0.8 µm of height), with interlaced woven structure on PET, and ITO elec.	Plasma dry etching	45.7 V kPa⁻¹ (0–0.71) 10.6 V kPa⁻¹ (0.71–1.25)	2.5 Pa/ 1.25 kPa	5/-	40,000 (L)	-/-	(♡)
TE	J. Zhou [292] 2018	EVA/Ag film with hollow micro-spheres (750 µm of diameter, 300 µm of height) in both surfaces, with an outer sheet of FEP/Ag.	Hot pressing	18.98 V kPa⁻¹ (0.5–1) 0.77 V kPa⁻¹ (1.6–10) 0.25 V kPa⁻¹ (10–40)	500 Pa/ 40 kPa	-/-	-	-/-	(♡)
TE	Z. L. Wang [176] 2019	Two PDMS films with micro-cones (25.4 µm of diameter, 25.7 µm of height) in interlocked geometry, one covered with Ag NWs and the other covered with PTFE bumps, and a back elec.	Leaf as mold	127.22 V kPa⁻¹ (5–50)	5 kPa/ 50 kPa	-/-	5000 (L)	-/-
TE	X. Chou [293] 2020	PDMS micro-frustum film (14 µm of width, 5 µm of height) covered with Cu with another PDMS micro-frustum film covered with P(VDF-TrFE) in interlocked geometry, and a spacer.	Photolit.	56.7 mV kPa⁻¹ (0–600) 15.6 mV kPa⁻¹ (700–1000)	-/1 MPa	60/-	80,000 (L)	-/-	(♡)