Stretchable inorganic electronics are very attractive for many applications, which require large deformation during stretching. Archimedean–inspired interconnect designs can offer and achieve high level of stretchability under extreme deformations. Here, we systematically investigate the relationship between stretchability and the geometrical parameters under in-plane deformation. The stretchable structures are made of amorphous silicon (a-Si), which cracked at very small strain 1.6%. Finite element method (FEM) was carried out to simulate the maximum strain/stress of interconnects. The results show that high stress appears at the base and the half-circle of the Archimedean interconnects. Experimental results agree well with the numerical modeling, both showing that the stretchability more than double when the straight line at the base is replaced by two lines in series. Our results demonstrate a stretchability up to 1020% and 605%, respectively for two types of Archimedean interconnect. The results indicate that the narrower width, the larger gap separated the straight lines (higher radius), and the longer straight lines will achieve lower stress and high stretchability. Further, a numerical study is conducted to explore the mechanical performance of Poly-crystalline silicon based structures where the maximum bending strain should be up to 1%.

The interest of stretchable electronics has increased due to their opportunities in many applications, starting from wearable electronics,1–3 to surgical tools,4,5 health monitoring systems,6,7 eye-ball like digital cameras,8,9 and stretchable sensors.10,11 The human body is soft, complex and its surface is asymmetric such as elbow, wrist, knee, etc. All recognized classes of high-performance electronics have to utilize inorganic materials, such as silicon, gold, nitrides or gallium arsenide, in forms that are bulky, stiff and even brittle and thus their elastic stretchabilities are very low around 1–1.65%.12–14 Nonetheless, silicon is biocompatible. Therefore, silicon electronics need to be designed to be stretched into complex shapes to absorb the strains associated with the deformation while keeping the device performance and reliability. When combined the mechanical designs with inorganic materials, the structures can be flexed, stretched, folded, twisted, bent and deformed along more axis or other modes without affecting their electrical performance and without any mechanical fatigue.15–17 

In stretchable electronics, several structural designs have been developed, including wavy, wrinkled or buckled, fractal and serpentine designs.18–20 The wavy and wrinkled structural designs are widely used in stretchable inorganic electronics. This is mainly because these designs show good conductivity and stretchability with soft compliant substrate. However, the wavy and wrinkled structures can only enhanced the stretchability in one axis. Compared with wavy designs, the fractal ones can be deformed in biaxial, radial and other deformation modes.21 A variety of fractal-inspired representative designs including lines (Koch, Hilbert, Peano), loops (Moore, Vicsek), branch-like meshes (Greeck cross), and horseshoe have been demonstrated to be useful for various applications.

The island-interconnect structure presents another architecture, which is widely used in stretchable electronics. Under stretch, the islands, which carry all the functional components, are kept nearly un-deformed. Unlike the islands, the electrical interconnects are mainly responsible to achieve high stretchability. However, the islands-interconnects design must be capable to achieve high space-filling geometry and high mechanical stretchability or large strain deformation, which requires a specific interconnects design with long length in small space. Many interconnect designs have been proposed such as non-coplanar, serpentine and fractal-inspired.22–24 The serpentines have been widely used as interconnects, when integrated serpentine ribbons on elastomer substrate, they can improve high stretchability (50%-1600%), depending on the various geometrical parameters.25 Xu et al. showed a biaxial stretchability of up to 300%, based on self-similar serpentines interconnects.26 Hussain et al. demonstrated stretchability up to 800% based on copper serpentine interconnects.27 Recently, the spiral-shaped interconnects showed high stretchability up to 1000%.28 Rojas et al. demonstrated a stretchable thermoelectric generator (TEG) based on spiral-inspired structures.29 More recently, Rehman et al. developed an optimization method through finite element analysis to reduce the stress and strain distribution along spiral-inspired structures.30 Lately, Qaiser et al. demonstrated the in-depth structural response of the spiral-island system when subjected to in-plane and out-of-plane stretchings.31 

Although serpentines-interconnects have been widely used as stretchable structures, Lv et al. have demonstrated that the Archimedean-based interconnects can offer higher stretchability compared to serpentine-based interconnects.32 The results show up to 250% of applied elastic strain and 325% without failure for archimedean interconnects design. Inspired by this work, we have modified the Archimedean design to increase the in-plane stretchability. In a recent work, we showed experimentally and theoretically the ability to get more than 1020% of stretchability based on Archimedean design.33 We have demonstrated that Archimedean structures can provide larger stretchability as compared to the spiral and serpentine structures. Moreover, the Archimedean shape optimization under in-plane deformation has not been performed.

The designs of Archimedean shape can be critically important to some applications which required high stretchability. This paper aims to study the relationship between the various geometrical parameters of Archimedean structures and the stretchability, to serve as design guidelines that can be useful for optimizing the stretchability. Experimental and Finite Element Modeling (FEM) have been conducting to investigate this relation. Our study focus on structures made of amorphous silicon (a-Si), which the width to thickness ratio is lower than one, and thus the stretchability is governed by in-plane deformation. Interconnects can be described by three serpentine designs with different radius linked together in small area. It contains of straight lines and arc circles that are joined in parallels. Experimental results show that the stretchability of the Archimedean spiral interconnects varies from 130% to 1020%, depending on various geometrical parameters such as width, gap space, and straight lines height. Further, a numerical study is conducted to explore the mechanical performance of Poly-crystalline silicon based structures where the maximum bending strain should be up to 1%.

Scanning electron microscopic (SEM) images and schematic of the islands-Archimedean interconnects are shown in Fig. 1. The islands represent in square shapes. The Archimedean structures contain a number of periodically distributed straight lines, with height (H) and width (w) connected by three half circles with radius from median line, (R1 R2, and R3), and the distance from end-to-end is (l). Two different architectures are studied in this paper, Type A (Fig. 1a) and Type B (Fig. 1b). As shown in Fig. 1(a), the base of the Archimedean interconnects type A consists of sets of half circle with radius (R3) and two sets of straight lines that are perpendicular to each other and connected in series. The Type B, as shown in Fig. 1(b), consists of sets of quarter circle with radius (R3) and straight line that are connected in series. Hence, to properly compare the elastic stretchability for both types, the various geometry parameters (w, H, R1,2,3, l) were considered uniform. In addition, interconnects can be described by three serpentine designs with different radius linked together in small area. As shown in the following, these geometrical parameters affect stretchability response of the structures.

FIG. 1.

Illustration of geometric parameters for Archimedean interconnects of (a) Type A and (b) Type B. (c)-(f) Scanning electron microscopy (SEM) images of the structures after release. (c) and (d) Island-Archimedean structure for Types A and B. (e) and (f) Enlargement of part of the Archimedean interconnects showing the width (w) and the gap (g) are almost 5 μm and 7 μm, respectively.

FIG. 1.

Illustration of geometric parameters for Archimedean interconnects of (a) Type A and (b) Type B. (c)-(f) Scanning electron microscopy (SEM) images of the structures after release. (c) and (d) Island-Archimedean structure for Types A and B. (e) and (f) Enlargement of part of the Archimedean interconnects showing the width (w) and the gap (g) are almost 5 μm and 7 μm, respectively.

Close modal

The structures are fabricated on a 10 μm amorphous silicon (a-Si) deposited on 300 nm thermally grown silicon dioxide (SiO2) on a bulk-Si (100) wafer. This deposition of a-Si makes it a virtual silicon-on-insulator (v-SOI).33 The deposition is done in presence of Silane gas using plasma enhanced chemical vapor deposition technique (PECVD) at chamber pressure of 1000 mTorr. A positive photoresist (PR) (ECI-3027) spin coating to make the pattern and the holes for releasing the thin a-Si structures from the wafer follows this deposition. Stretchable Archimedean interconnect structures and holes in the square islands are patterned using broadband light with an energy of 200 mJ/cm2 followed by photoresist development in AZ- 726 MIF developer for 60 s. Deep reactive ion etching (DRIE) is performed to etch 10 μm of a-Si protecting the structures using PR at 10 mTorr pressure, 10 °C and using the combination of C4F8:SF6 in two steps of deposition (100:10) and etching (5:120). The deposition step in DRIE is to protect the sidewalls in the structures for obtaining the vertical profile of holes and the structures. Finally, vapor HF at 40 °C is used to selectively etch SiO2 under a-Si layer, releasing the structures from v-SOI wafer and the released structures are characterized for stretchability and mechanical strength explained in details later. Figs. 1(b) and 1(c) show SEM images of the fabricated devices for the two types A and B. For our fabrication, the height (H) is varying from 150 μm to 400 μm. We have kept the width of the Archimedean arms as 5 μm and 7 μm, which can further be decreased to give improved performance. In our study, we only consider the Archimedean structures whose width/thickness ratio is lower than 1. Under stretching, the deformation is directed by in plane bending.

3D Finite element method (FEM) analysis is performed, using COMSOL software, to investigate the relationship between the stretchability and various geometrical parameters. We used Solid Mechanics module to simulate the structures. To achieve the in-plane stretchability of islands-Archimedean interconnects, an in-plane displacement is applied on one of the islands while the second one was declared as fixed. Since the structures show high stretchability and thus large deformation, non-linear geometry was used. Amorphous silicon (a-Si) was used as the material for the device with Young’s modulus E = 80 GPa, and free tetrahedral mesh with custom element size was used to mesh the device for accurate results. The stretchability is defined as the critical applied strain which the amorphous silicon of the Archimedean structure will fracture (εmax=1.6%). Let β and α denote the height/gap ratio (H/g) and the width/gap ratio (w/g), respectively. The following subsection presents an investigation of the influence of the two parameters β and α on the in-plane deformation of the Archimedean structure and its stretchability. Moreover, we present a detailed analysis of the effects of the gap or arc radius on the maximum stress and the stretchability. For mechanical characterization, we uniaxial stretched our structure using probe station, and optical images under in-plane deformation were taken with a single-lens camera. An axial displacement is applied manually by using one of the probe needles on one of the islands while the second one was fixed.

Although Archimedean interconnects have been achieved high stretchability of stiff materials, the mechanical responses of these interconnects are critically important to practical applications.33 Under in-plane deformation, two mechanical behaviors should be studied, the induced stress and the stretchability. Hence, when the induced stress reaches the critical stress (strain), this could lead interconnects enters the fracture zone. This stress could limit the stretchability of the structures. Therefore, optimize the design is important to avoid interconnects cracking. Experimental results demonstrate that the structure have 1.6% as the maximum of the strain before fracture. In FEM, stretchability is defined as the largest in-plane deformation that does not cause yield cracking in interconnects. Experimental and finite element method (FEM) studies of the underlying mechanics of stress on the two types of Archimedean interconnects made of amorphous silicon, with β = 80 and α = 1 under 170% of axial strain are shown in Fig. 2. Figs. 2(c) and 2(d) show the 3D maximum strain (εmax) is 0.6% and 0.4%, for Type A and Type B, respectively. It should be noted that for both types, the εmax is lower than 1.6%. For low values of axial strain, the results indicate that Type B with one straight line in series with the quarter circle oriented in the same way as the Type A, minimizes the maximum stress and thus maximizes the uniaxial deformation. Hence, the uniaxial deformation response of Type A differs from the one of Type B (see Figs. 2(e) and 2(f)). In contrast, when a displacement is applied at one of the islands, it is suspected that, the Type B which showed the lower stress will achieve higher stretchability compared to the Type A.

FIG. 2.

(a)-(b) Schematics of Archimedean structures A and B at initial state. (c)-(f) Experimental and corresponding FEM results of 170% of deformed interconnects for the two types A and B. 3D maximum strain (εmax) is 0.6% and 0.4%, for Type A and Type B, respectively.

FIG. 2.

(a)-(b) Schematics of Archimedean structures A and B at initial state. (c)-(f) Experimental and corresponding FEM results of 170% of deformed interconnects for the two types A and B. 3D maximum strain (εmax) is 0.6% and 0.4%, for Type A and Type B, respectively.

Close modal

Fig. 3 shows the experimental results of the Archimedean structures for α = 1 and β = 80 under different axial strain test values. The results demonstrate a stretchability up to 1020% (605%) for the Type A (Type B) before fracture εmax = 1.6%. Hence, Type A microstructures offer much higher stretchability than Type B. The fact that, Type A allowed a high stretchability related to the end-to-end length (l) of the two types, rather than mechanical difference in the structures. Under stretching, the Archimedeans start to unwrap, and thus it is observed from the experimental results of Figs. 3(a) and 3(b) that, under almost 500% of axial strain, 30% of the surface of Type A is unwrapped while Type B shows almost 70%. In addition, it is important to remark for both types, the failure occurs at the half circles, which can be explained by the presence of maximum stress on this region. During the unwrapping process, the zone near the base of interconnects exposed maximum von Mises stress. However, the results demonstrate that the maximum stress which appears at the half circle (quarter circle) may be due to the large bending moment at this point. Therefore the chosen specific Archimedean shape (Type A or Type B) can help to reduce the maximum induced strain and becomes lower than the fracture value.

FIG. 3.

Full extension test under several stages of applied tensile strain until fracture for (a) Type A and (b) Type B. Interconnects have Height/gap ratio β = 80 and width/gap ratio α=1. For the two types, the failure yield appears at the half circles.

FIG. 3.

Full extension test under several stages of applied tensile strain until fracture for (a) Type A and (b) Type B. Interconnects have Height/gap ratio β = 80 and width/gap ratio α=1. For the two types, the failure yield appears at the half circles.

Close modal

Figs. 4(a) and 4(b) show the experimental results and finite element simulations of the Archimedean structures for both types A (β = 30, α = 1) and B (β = 30, α = 1.4) under different axial strain values. The experimental results show that for both types, the failure occurs at the base of interconnects (beginning or end), which can be explained by the presence of maximum stress on this region. We conclude that, the structure with low values β, the maximum stress appears at the end of interconnects whereas for high values it is induced at the half circles. For both types, FEM results show that the 3D maximum stress εmax is 1.6% which represents the yield fracture. The results demonstrate stretchability up to 170% and 135%, respectively for Type A and Type B. Fig. 4 shows also a FEM comparison of the distribution of the maximum stress between the two types. The results indicate that the maximum strain and stress appear at the base of the structure and at the half-circle for the Type A. This result shows that interconnects with high radius must be considered to reduce the strain (stress) at the half circle. In the future work, to minimize the stress localization which appears at the bases of interconnects, it is required to replace the straight arms with serpentines.28,30

FIG. 4.

Full extension test under several stages of applied tensile strain until fracture and corresponding FEM results for (a) Type A with β= 30 and α=1 and (b) Type B with β = 30 and α=1.4. The enlarged view shows a maximum stress at the half circle and the base of the interconnections for the two Types.

FIG. 4.

Full extension test under several stages of applied tensile strain until fracture and corresponding FEM results for (a) Type A with β= 30 and α=1 and (b) Type B with β = 30 and α=1.4. The enlarged view shows a maximum stress at the half circle and the base of the interconnections for the two Types.

Close modal

Since it has been observed that during the unwrapped process, the induced maximum strain varies from Type A to Type B and for low β to higher ones. Furthermore, it has been noticed that the maximum stress might appear at the beginning (end) of interconnects and at the half circles. Therefore, we have introduced a systematic analysis on the stretchability and present a design optimization of two types. The influence of geometric parameters (α = w/g and β = H/g) on the stretchability (εstretchability) for the two types is shown in Fig. 5. The FEM and experimental results are summarized in Figs. 5(a) and 5(b). However, a good agreement is shown among all the results. According to these figures, for a fixed α and gap g = 5μm, the stretchabilities of both types increase with the increase of β. A reasonable interpretation is that, increasing β for low to high, the height (H) increases and thus the total end-to-end length increases, which this significantly reduces the overall structure stiffness. Hence, under the same in-plane applied strain, we report high stretchability for high β. Hence, the results indicate that the stretchability of both types of interconnects can be increased by simply increase the straight lines. At α = 1 and for 30< β<80, the evolution of stretchability is between 175% to 1020% and 210% to 605%, respectively for the two types. However, for α = 1.4, the evolution of the stretchability becomes between 75% to 700% and 140% to 520%, respectively. Moreover, the results show that a high stretchability corresponds to a thin width (α = 1). The experimental results in Fig. 5(c) indicate that for β lower than 40, the stretchability in the case of Type B is higher than the Type A and considering that the increase of (β>40) would be lead to the reduction of the evolution of the stretchability for the Type B compared to the Type A, due to the increase of the stiffness that makes the structure harder to stretch.

FIG. 5.

Experimental and FEM results of the relationship between the maximum stretchability (εstretchability), and β and α for (a) Type A and (b) Type B. (c) Experimental results of the stretchability versus β for two types A and B and for two values of α=(1,1.4), and a fixed gap g=5μm.

FIG. 5.

Experimental and FEM results of the relationship between the maximum stretchability (εstretchability), and β and α for (a) Type A and (b) Type B. (c) Experimental results of the stretchability versus β for two types A and B and for two values of α=(1,1.4), and a fixed gap g=5μm.

Close modal

Next, we present the mechanical responses (maximum stress/strain) of interconnects under a prescribed displacement of 100 μm and at α = 1. Figs. 6(a) and 6(b) show the maximum von Mises stress distribution (σmax) under different values of β for the two types. It is found that the highest value of σmax corresponds to β = 30. By increasing β until 80, σmax was reduced from 807 MPa to 242 MPa for type A and from 766 MPa to 252 MPa for Type B, respectively. Hence, the induced strains and stresses depend on β of interconnects. For β<40, when interconnects start to deform in the in-plane direction, the forces are generated in the horizontal straight line for Type B and in L shape lines for Type A. Thus, Type A will demonstrate higher stress since it has higher stiffness compared to Type B as shown in Figs. 6(c) and 6(d). The stiffness can be reduced by simply increasing the height of lines. The results also indicate that for β>80, Type A will experience lower stress since the maximum stress appears at the half circles, and thus it may due to the large bending moment at this point.

FIG. 6.

At a prescribed displacement 100 μm and α=1, FEM results of the distribution of von Mises stress for (a) Type A and (b) Type B. For the two types, (c) maximum strain and (d) maximum von Mises stress for different values of β. For low values β<40, the maximum strain/stress for Type B is lower than Type A, when it increases, corresponding strain/stress becomes higher for Type B than Type A.

FIG. 6.

At a prescribed displacement 100 μm and α=1, FEM results of the distribution of von Mises stress for (a) Type A and (b) Type B. For the two types, (c) maximum strain and (d) maximum von Mises stress for different values of β. For low values β<40, the maximum strain/stress for Type B is lower than Type A, when it increases, corresponding strain/stress becomes higher for Type B than Type A.

Close modal

Following, a systematic study of the relationship between the stretchability and gap (g) is performed. Since no experimental results have been done regarding the stretchability of the interconnects with different gap, we only based our study on FEM. Fig. 7(a) shows the simulation results of the dependence on stretchability response for the two types. It is observed that the stretchabilities of both types increase with the increase of the gap distance (g). As g increases, the radius (R1,2,3) increases. In our previous work, we showed that the maximum strain is inversely proportional to the radius of the half circles. Hence, Archimedean structures with high radius has high stretchability. In case of β= 80 and for Type B, the maximum variation on the stretchability founded is 13%. Figs. 7(c) and 7(d) plot the maximum stress distribution on the two types of interconnects as a function of g. We found that, the effect of the gap on maximum stress on the two types, is higher for low values of β. At β = 30 and for Type A, the maximum stress with g=7μm (807 MPa) was reduced compared to interconnects with g=5μm (700 MPa), see Fig. 7(c). Similarly for Type B, the maximum value of stress was founded to be 710 MPa, which it lower 8% than interconnects with g=5μm as shown in Fig. 7(d).

FIG. 7.

FEM results of the εstretchability versus β at α=1 for various (a) gap g and for (b) silicon materials: Amorphous and poly-crystalline. Maximum von Mises stress as a function of β and g for (c) Type A and (d) Type B. It is essential to remark that there is a significant effect of gap (g) on stress for Type A.

FIG. 7.

FEM results of the εstretchability versus β at α=1 for various (a) gap g and for (b) silicon materials: Amorphous and poly-crystalline. Maximum von Mises stress as a function of β and g for (c) Type A and (d) Type B. It is essential to remark that there is a significant effect of gap (g) on stress for Type A.

Close modal

Nowadays, most of the electronics are based on inorganic semiconductors materials. Therefore, stretchable high-performance electronics need to use mono/poly-crystalline silicon (c-Si) or amorphous silicon (a-Si). Hence, the values of the stretchability of the Archimedean structures based on poly-crystalline silicon are required. Fig. 7(b) shows the FEM results of the stretchability for poly-crystalline silicon Archimedean interconnects compared to whose the structures based on amorphous silicon. Material properties of poly -crystalline isotropic (c-Si) were taken as follows: Elastic modulus E = 169 GPa, and Poisson’s ratio ν = 0.22. According to the FEM results, the amount of the variation of the stretchability between the two materials of silicon increases as the ratio β increases. For β = 30 and for Type A, the maximum stretchability can be decreased from 164% to 153% (7%). For β = 80, the variation range is about (28%) from 1025% to 750% while for type B it is about (43%) from 600% to 345%.

However, the mechanical performance of the proposed design can be evaluated based on two criteria: stretchability and maximum principal strain. Hence, stretchable structures based on islands-bridges designs must achieve high stretchability of the bridges, which typically requires long bridges between the islands. In this paper, we showed that even with small bridges (l) lower than 120 μm, we achieved high stretchability up to 1020%. Based on experimental and FEM analysis, we have obtained enough results for optimized structures. The stretchability can be improved by decreasing the width of interconnects less than 5 μm or increasing the height of the straight lines higher than 400 μm. In supplementary material, we show FEM results of the stretchability for the two types at w = 3μm. Nevertheless, islands –Archimedean structures must achieve high stretchability in a small spacing between the islands, for this reason in supplementary material we showed a study of the effect of geometrical parameters g = 3μm and H< 200 μm on the stretchability. To guarantee the elastic stretchability of the structures, the Finite simulation studies has limited to maximum strain (εmax = 1%). As expected, with increasing H, maximum strain decreases. Fig. S1 shows the maximum strain as function of applied strain for the two types. It shows that under 80% of applied strain, the maximum strain decreases from 1.09% to 0.45% for Type A and from 1.06% to 0.3% for Type B, respectively. Fig. S2 shows that, the stretchability of both types increases with the increase in the height/width ratio. Also, for εmax = 1%, it can be observed that the stretchability of two follows the same trend for low height/width ration until it reaches 50, while for εmax = 1.6%, there is more effect of the increasing of the height/width ratio on the Type B than Type A. The maximum stretchability gap between the two types increases gradually with the increasing of the ratio. However, for H = 200 μm, the stretchability increases from 240% to 350% for Type A and from 275% to 425% for Type B. Also, we should notice here the number of half circles can achieve higher stretchability. In our proposed design, we limited our study to three half circles while we can increase it. In our previous work, it is found that increasing the number of half circles from 2 to 3 is a very effective way to reduce the maximum von Mises stress in Archimedean, which will lead to significant increasing of the stretchability from 134% to 540%, for β = 40. This simplified study shows us, to allow a specific stretchability, we should increase the number of half circles. Furthermore, we noticed that for low values of β, the maximum stress appears at the end or beginning of the base interconnects. This can be resolved by replacing the straight lines at the ends by serpentine of fractal inspired structures to optimize and reduce the stress along them. This last encourage us to combine the serpentine with Archimedean structures, to optimize their mechanical behavior, thus accomplishing more stretchability. For High values of β, the maximum stress appears at the half circles. This can be resolved by also increasing the radius of the half circles, in the case of spiral and serpentine structures, Rojas et al.28 showed that the maximum stress is inversely proportional to the radius of the half-circle. Compared to the serpentine design, Archimedean design contains three cells serpentine with arc radius (R1, R2, and R3). Consequently, the design should try to maximize the radius of the Archimedean interconnects. However, the advantage of this design is that it can offer high stretchability in a small area. In addition, most of stretchable structures are made of inorganic materials such as silicon, gold, and copper, thus to minimize the maximum strains in metal interconnects under large deformation, the chosen of proper material is recommended. For example, Archimedean interconnects with amorphous silicon shows 1020% while with poly-silicon this value becomes 750%. Hence, a systematic study of the stretchability with different inorganic materials is performed. The actual analysis proposed in this paper can be used to guide designs in the islands-Archimedean interconnects structure that achieve in the same time high covered empty gap spacing between the neighboring islands and allow high reversibility with small area.

This paper presented two types of Archimedean interconnects stretchable structures based on amorphous silicon. We have studied the relationship between stretchabilities and different geometrical parameters. After the design optimization study, the experimental results with FEM show that the thinner and the longer straight lines interconnects give very large stretchability of the system, such as 1020% and 605% for the two types. In addition, it is found that increasing the gap between the straight lines is a very effective way to increase the stretchability of the Archimedean structures. Compared with interconnects structures based on poly-crystalline silicon, the results show that, the maximum stretchability can be decreased from 1025% to 750% (28%). These results are valuable for future miniature devices, which need extremely stretchable interconnects in microscale by fabricated thinner and longer straight lines or by increasing the gap between them.

See supplementary material for figures showing the effect of the gap (g) and height (H) on the maximum stretchability and maximum strain.

This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST).

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