Gait Pattern Analysis: Integration of a Highly Sensitive Flexible Pressure Sensor on a Wireless Instrumented Insole.

Gait phase monitoring wearable sensors play a crucial role in assessing both health and athletic performance, offering valuable insights into an individual's gait pattern. In this study, we introduced a simple and cost-effective capacitive gait sensor manufacturing approach, utilizing a micropatterned polydimethylsiloxane dielectric layer placed between screen-printed silver electrodes. The sensor demonstrated inherent stretchability and durability, even when the electrode was bent at a 45-degree angle, it maintained an electrode resistance of approximately 3 Ω. This feature is particularly advantageous for gait monitoring applications. Furthermore, the fabricated flexible capacitive pressure sensor exhibited higher sensitivity and linearity at both low and high pressure and displayed very good stability. Notably, the sensors demonstrated rapid response and recovery times for both under low and high pressure. To further explore the capabilities of these new sensors, they were successfully tested as insole-type pressure sensors for real-time gait signal monitoring. The sensors displayed a well-balanced combination of sensitivity and response time, making them well-suited for gait analysis. Beyond gait analysis, the proposed sensor holds the potential for a wide range of applications within biomedical, sports, and commercial systems where soft and conformable sensors are preferred.

Debossed Contact Printing as a Patterning Method for Paper-Based Electronics.

The proliferation of printed electronic devices is feeding the growth of the Internet of Things, with devices deployed everywhere to collect and communicate data. At the same time, the increase in low-cost disposable devices is a cause for serious environmental concern. In particular, widely used plastic substrates such as poly(ethylene terephthalate) are persistent hazards to the environment. Paper is promising as a greener substrate for printed electronics because it is biodegradable and sourced from renewable materials as well as being low cost and compatible with roll-to-roll printing. However, the porous microstructure of paper promotes wicking of functional inks, leading to poor electrical performance and printing resolution. Hydrophobic coatings applied to the surface of paper create a planarized, printable surface, but these materials may compromise biodegradability and/or recyclability. This paper describes a new resist-free patterning method for printed paper-based electronics that takes advantage of the porous structure of paper. Debossed contact printing uses the pressure from a debossing tip to compress the porous structure of paper and create a patterned relief structure. Printing functional inks with an unpatterned roller deposits ink only on the raised regions of the relief structure. We demonstrate debossed contact printing of silver, carbon black, and conducting polymer inks and show that this new fabrication method is suitable for the fabrication of printed devices with dense features. We demonstrate the fabrication of antennas and patterned electrodes for RFID and smart wallpaper applications, respectively.

Conducting materials as building blocks for electronic textiles.

ABSTRACT: To realize the full gamut of functions that are envisaged for electronic textiles (e-textiles) a range of semiconducting, conducting and electrochemically active materials are needed. This article will discuss how metals, conducting polymers, carbon nanotubes, and two-dimensional (2D) materials, including graphene and MXenes, can be used in concert to create e-textile materials, from fibers and yarns to patterned fabrics. Many of the most promising architectures utilize several classes of materials (e.g., elastic fibers composed of a conducting material and a stretchable polymer, or textile devices constructed with conducting polymers or 2D materials and metal electrodes). While an increasing number of materials and devices display a promising degree of wash and wear resistance, sustainability aspects of e-textiles will require greater attention.

Wearable E-Textiles Using a Textile-Centric Design Approach.

Electronics worn on the body have the potential to improve human health and the quality of life by monitoring vital signs and movements, displaying information, providing self-illumination for safety, and even providing new routes for personal expression through fashion. Textiles are a part of daily life in clothing, making them an ideal platform for wearable electronics. The acceptance of wearable e-textiles hinges on maintaining the properties of textiles that make them compatible with the human body. Beneficial properties such as softness, stretchability, drapability, and breathability come from the 3D fibrous structures of knitted and woven textiles. However, these structures also present considerable challenges for the fabrication of wearable e-textiles. Fabrication methods used for modern electronic devices are designed for 2D planar substrates and are mostly unsuitable for the complex 3D structures of textiles. There is thus an urgent need to develop fabrication methods specifically for e-textiles to advance wearable electronics. Solution-based fabrication methods are a promising approach to fabricating wearable e-textiles, especially considering that textiles have been successfully modified using pigmented dyes in dyebaths and printing inks for thousands of years. In this Account, we discuss our research on the solution-based electroless metallization of textiles to fabricate conductive e-textiles that are building blocks for e-textile devices. Electroless metallization solutions fully permeate textile structures to deposit metallic coatings on the surfaces of individual textile fibers, maintaining the inherent textile structures and wearability. The resulting e-textiles are highly conductive, soft, and stretchable. We furthermore discuss ways to turn the challenges related to textile structures into new opportunities by strategically using the structural features of textiles for e-textile device design. We demonstrate this textile-centric approach to designing e-textile devices using two examples. We discuss how the structure of an ultrasheer knitted textile forms a useful framework for new e-textile transparent conductive electrodes and describe the implementation of these electrodes to form highly stretchable light-emitting e-textiles. We also show how the structural features of velour fabrics form the basis for an innovative "island-bridge" strain-engineering structure that enables the integration of brittle electroactive materials and protects them from strain-induced damage, leading to the fabrication of stretchable textile-based lithium-ion battery electrodes. With the vast variety of textile structures available, we highlight the opportunities associated with this textile-centric design approach to advance textile-based wearable electronics. Such advances depend on a deep understanding of the relationship between the textile structure and the device requirements, which may potentially lead to the development of new textile structures customized to support specific devices. We conclude with a discussion of the challenges that remain for the future of e-textiles, including durability, sustainability, and the development of performance standards.

Protocol for fabricating electroless nickel immersion gold strain sensors on nitrile butadiene rubber gloves for wearable electronics.

This protocol describes the fabrication of patterned conductive gold films on nitrile butadiene rubber (NBR) gloves for wearable strain sensors using electroless nickel immersion gold (ENIG) plating, a solution-based metallization technique. The resulting NBR/ENIG films are strain sensitive; resistance measurements of a patterned sensing array can be used to map human hand motions. This protocol also describes challenges related to the ENIG process and troubleshooting steps to achieve conformal gold films for strain sensing over a large working range. For complete details on the use and execution of this protocol, please refer to Mechael et al. (2021).

Ready-to-wear strain sensing gloves for human motion sensing.

Integrating soft sensors with wearable platforms is critical for sensor-based human augmentation, yet the fabrication of wearable sensors integrated into ready-to-wear platforms remains underdeveloped. Disposable gloves are an ideal substrate for wearable sensors that map hand-specific gestures. Here, we use solution-based metallization to prepare resistive sensing arrays directly on off-the-shelf nitrile butadiene rubber (NBR) gloves. The NBR glove acts as the wearable platform while its surface roughness enhances the sensitivity of the overlying sensing array. The NBR sensors have a sheet resistance of 3.1 ± 0.6 Ω/sq and a large linear working range (two linear regions ≤70%). When stretched, the rough NBR substrate facilitates microcrack formation in the overlying metal, enabling high gauge factors (62 up to 40% strain, 246 from 45 - 70% strain) that are unprecedented for metal film sensors. We apply the sensing array to dynamically monitor gestures for gesture differentiation and robotic control.

25 Years of Light-Emitting Electrochemical Cells: A Flexible and Stretchable Perspective.

Light-emitting electrochemical cells (LECs) are simple electroluminescent devices comprising an emissive material containing mobile ions sandwiched between two electrodes. The operating mechanism of the LEC involves both ionic and electronic transport, distinguishing it from its more well-known cousin, the organic light-emitting diode (OLED). While OLEDs have become a leading player in commercial displays, LECs have flourished in academic research due to the simple device architecture and unique features of its operating mechanism, inviting exploration of new materials and fabrication strategies. These explorations have brought LECs to an exciting frontier in advanced optoelectronics: flexible and stretchable light-emitting devices. Flexible and stretchable LECs are discussed herein, presenting the LEC system as a robust and fault-tolerant development platform. The engineering of emissive composites is highlighted to control mechanical properties, and how the tolerance of LECs to electrode work function and roughness has enabled the incorporation of new electrode materials to achieve flexibility and stretchability. As part of this story, the solution processability of LECs has led to exciting demonstrations of flexible and printed LECs. An outlook is provided for LECs that builds on these strengths, potentially leading to flexible, stretchable, low-cost devices such as illuminated tags, smart packaging, flexible signage, and wearable illumination.

Velour Fabric as an Island-Bridge Architectural Design for Stretchable Textile-Based Lithium-ion Battery Electrodes.

The advancement of wearable electronics depends on the seamless integration of lightweight and stretchable energy storage devices with textiles. Integrating brittle energy storage materials with soft and stretchable textiles, however, presents a challenging mechanical mismatch. It is critical to protect brittle energy storage materials from strain-induced damage and at the same time preserve the softness and stretchability of the functionalized e-textile. Here, we demonstrate the strategic use of a warp-knitted velour fabric in an "island-bridge" architectural strain-engineering design to prepare stretchable textile-based lithium-ion battery (LIB) electrodes. The velour fabric consists of a warp-knitted framework and a cut pile. We integrate the LIB electrode into this fabric by solution-based metallization to create the warp-knitted framework current collector "bridges" followed by selective deposition of the brittle electroactive material CuS on the cut pile "islands". As the textile electrode is stretched, the warp-knitted framework current collector elongates, while the electroactive cut pile fibers simply ride along at their anchor points on the framework, protecting the brittle CuS coating from strain and subsequent damage. The textile-based stretchable LIB electrode exhibited excellent electrical and electrochemical performance with a current collector sheet resistance of 0.85 ± 0.06 Ω/sq and a specific capacity of 400 mAh/g at 0.5 C for 300 charging-discharging cycles as well as outstanding rate capability. The electrical performance and charge-discharge cycling stability of the electrode persisted even after 1000 repetitive stretching-releasing cycles, demonstrating the protective functionality of the textile-based island-bridge architectural strain-engineering design.

Patterned, Flexible, and Stretchable Silver Nanowire/Polymer Composite Films as Transparent Conductive Electrodes.

The emergence of flexible and stretchable optoelectronics has motivated the development of new transparent conductive electrodes (TCEs) to replace conventional brittle indium tin oxide. For modern optoelectronics, these new TCEs should possess six key characteristics: low cost, solution-based processing; high transparency; high electrical conductivity; a smooth surface; mechanical flexibility or stretchability; and scalable, low-cost patterning methods. Among many materials currently being studied, silver nanowires (AgNWs) are one of the most promising, with studies demonstrating AgNW films and composites that exhibit each of the key requirements. However, AgNW-based TCEs reported to date typically fulfill two or three requirements at the same time, and rare are examples of TCEs that fulfill all six requirements simultaneously. Here, we present a straightforward method to fabricate AgNW/polymer composite films that meet all six requirements simultaneously. Our fabrication process embeds a AgNW network patterned using a solution-based wetting-dewetting protocol into a flexible or stretchable polymer, which is then adhered to an elastomeric poly(dimethylsiloxane) substrate. The resulting patterned AgNW/polymer films exhibit ∼85% transmittance with an average sheet resistance of ∼15 Ω/sq, a smooth surface (a root-mean-square surface roughness value of ∼22 nm), and also withstand up to 71% bending strain or 70% stretching strain. We demonstrate the use of these new TCEs in flexible and stretchable alternating current electroluminescent devices that emit light to 20% bending strain and 60% stretching strain.

Developing the Surface Chemistry of Transparent Butyl Rubber for Impermeable Stretchable Electronics.

Transparent butyl rubber is a new elastomer that has the potential to revolutionize stretchable electronics due to its intrinsically low gas permeability. Encapsulating organic electronic materials and devices with transparent butyl rubber protects them from problematic degradation due to oxygen and moisture, preventing premature device failure and enabling the fabrication of stretchable organic electronic devices with practical lifetimes. Here, we report a methodology to alter the surface chemistry of transparent butyl rubber to advance this material from acting as a simple device encapsulant to functioning as a substrate primed for direct device fabrication on its surface. We demonstrate a combination of plasma and chemical treatment to deposit a hydrophilic silicate layer on the transparent butyl rubber surface to create a new layered composite that combines Si-OH surface chemistry with the favorable gas-barrier properties of bulk transparent butyl rubber. We demonstrate that these surface Si-OH groups react with organosilanes to form self-assembled monolayers necessary for the deposition of electronic materials, and furthermore demonstrate the fabrication of stretchable gold wires using nanotransfer printing of gold films onto transparent butyl rubber modified with a thiol-terminated self-assembled monolayer. The surface modification of transparent butyl rubber establishes this material as an important new elastomer for stretchable electronics and opens the way to robust, stretchable devices.

A Self-Assembled, Low-Cost, Microstructured Layer for Extremely Stretchable Gold Films.

We demonstrate a simple, low-cost, and green approach to deposit a microstructured coating on the silicone elastomer polydimethylsiloxane (PDMS) that can be coated with gold to produce highly stretchable and conductive films. The microstructured coating is fabricated using an aqueous emulsion of poly(vinyl acetate) (PVAc): common, commercially available white glue. The aqueous glue emulsion self-assembles on the PDMS surface to generate clustered PVAc globules, which can be conformally coated with gold. The microstructured surface provides numerous defect sites that localize strain when the structure is stretched, resulting in the initiation of numerous microcracks. As the structure is further elongated, the microcracks interact with one another, preventing long-range crack propagation and thus preserving the conduction pathway. The resistance of PDMS/glue/gold structures remains remarkably low (23 times the initial resistance) up to 65% elongation, making these structure useful as stretchable interconnects. Decreasing the concentration of the PVAc aqueous emulsion reduces the density of defect sites of the microstructure, which increases the change in resistance of the gold films with stretching. In this way, we can tune the resistance changes of the PDMS/glue/gold structures and increase their sensitivity to strain. We demonstrate the use of these structures as wearable, soft strain sensors.

Odd-even effects in charge transport across n-alkanethiolate-based SAMs.

This paper compares rates of charge transport across self-assembled monolayers (SAMs) of n-alkanethiolates having odd and even numbers of carbon atoms (nodd and neven) using junctions with the structure M(TS)/SAM//Ga2O3/EGaIn (M = Au or Ag). Measurements of current density, J(V), across SAMs of n-alkanethiolates on Au(TS) and Ag(TS) demonstrated a statistically significant odd-even effect on Au(TS), but not on Ag(TS), that could be detected using this technique. Statistical analysis showed the values of tunneling current density across SAMs of n-alkanethiolates on Au(TS) with nodd and neven belonging to two separate sets, and while there is a significant difference between the values of injection current density, J0, for these two series (log|J0Au,even| = 4.0 ± 0.3 and log|J0Au,odd| = 4.5 ± 0.3), the values of tunneling decay constant, ß, for nodd and neven alkyl chains are indistinguishable (ßAu,even = 0.73 ± 0.02 Å(-1), and ßAu,odd= 0.74 ± 0.02 Å(-1)). A comparison of electrical characteristics across junctions of n-alkanethiolate SAMs on gold and silver electrodes yields indistinguishable values of ß and J0 and indicates that a change that substantially alters the tilt angle of the alkyl chain (and, therefore, the thickness of the SAM) has no influence on the injection current density across SAMs of n-alkanethiolates.

Ultrasmooth gold surfaces prepared by chemical mechanical polishing for applications in nanoscience.

For over 20 years, template stripping has been the best method for preparing ultrasmooth metal surfaces for studies of nanostructures. However, the organic adhesives used in the template stripping method are incompatible with many solvents, limiting the conditions that may subsequently be used to prepare samples; in addition, the film areas that can be reliably prepared are typically limited to ∼1 cm(2). In this article, we present chemical-mechanical polishing (CMP) as an adhesive-free, scalable method of preparing ultrasmooth gold surfaces. In this process, a gold film is first deposited by e-beam evaporation onto a 76-mm-diameter silicon wafer. The CMP process removes ∼4 nm of gold from the tops of the grains comprising the gold film to produce an ultrasmooth gold surface supported on the silicon wafer. We measured root-mean-square (RMS) roughness values using atomic force microscopy of 12 randomly sampled 1 µm × 1 µm areas on the surface of the wafer and repeated the process on 5 different CMP wafers. The average RMS roughness was 3.8 ± 0.5 Å, which is comparable to measured values for template-stripped gold (3.7 ± 0.5 Å). We also compared the use of CMP and template-stripped gold as bottom electrical contacts in molecular electronic junctions formed from n-alkanethiolate self-assembled monolayers as a sensitive test bed to detect differences in the topography of the gold surfaces. We demonstrate that these substrates produce statistically indistinguishable values for the tunneling decay coefficient ß, which is highly sensitive to the gold surface topography.

The unusual self-organization of dialkyldithiophosphinic acid self-assembled monolayers on ultrasmooth gold.

We report the formation and characterization of self-assembled monolayers (SAMs) of dialkyldithiophosphinic acid adsorbates [CH3(CH2)n]2P(S)SH (R2DTPA) (n = 5, 9, 11, 13, 15) on ultrasmooth gold substrates prepared by the template stripping method. The SAMs were characterized using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle measurements, lateral force microscopy, and electrochemical impedance spectroscopy. The data show these SAMs exhibit an unusual trend in alkyl chain crystallinity; SAMs formed from adsorbates with short alkyl chains (n = 5) are ordered and crystalline, and the alkyl groups become increasingly disordered and liquidlike as the number of methylene units is increased. This trend is the opposite of the typical behavior exhibited by n-alkanethiolate SAMs, in which the alkyl layer becomes more crystalline and ordered as the alkyl chain length is increased. We discuss four factors that operate together to determine how R2DTPA self-organize within SAMs on TS gold: (i) adsorbate-substrate interactions; (ii) gold substrate morphology; (iii) lateral van der Waals interactions between alkyl groups; and (iv) steric demands of the alkyl groups. We also present a model for the structures of these SAMs on the basis of consideration of the data and the structural parameters of a model (n)Bu2DTPA adsorbate. In this model, interdigitation of short alkyl chains stabilizes a trans-extended, crystalline arrangement and produces an ordered alkyl layer. As the alkyl chain length is increased, the increased steric demands of the alkyl groups lead to liquidlike, disorganized alkyl layers.

Silver nanowire/optical adhesive coatings as transparent electrodes for flexible electronics.

We present new flexible, transparent, and conductive coatings composed of an annealed silver nanowire network embedded in a polyurethane optical adhesive. These coatings can be applied to rigid glass substrates as well as to flexible polyethylene terephthalate (PET) plastic and elastomeric polydimethylsiloxane (PDMS) substrates to produce highly flexible transparent conductive electrodes. The coatings are as conductive and transparent as indium tin oxide (ITO) films on glass, but they remain conductive at high bending strains and are more durable to marring and scratching than ITO. Coatings on PDMS withstand up to 76% tensile strain and 250 bending cycles of 15% strain with a negligible increase in electrical resistance. Since the silver nanowire network is embedded at the surface of the optical adhesive, these coatings also provide a smooth surface (root mean squared surface roughness<10 nm), making them suitable as transparent conducting electrodes in flexible light-emitting electrochemical cells. These devices continue to emit light even while being bent to radii as low as 1.5 mm and perform as well as unstrained devices after 20 bending cycles of 25% tensile strain.

New dihexadecyldithiophosphate SAMs on gold provide insight into the unusual dependence of adsorbate chelation on substrate morphology in SAMs of dialkyldithiophosphinic acids.

We report the formation and characterization of new self-assembled monolayers (SAMs) formed from dihexadecyldithiophosphate (C16)2DDP and compare their properties with those of SAMs formed from the structurally similar adsorbate dihexadecyldithiophosphinic acid (C16)2DTPA. The new (C16)2DDP SAMs were characterized using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle measurements, and electrochemical impedance spectroscopy. The data indicate that (C16)2DDP forms SAMs on gold films formed by e-beam evaporation in which all adsorbates chelate to gold, in contrast to (C16)2DTPA SAMs, in which 40% of the adsorbates are monodentate. The alkyl chains of the (C16)2DDP SAM are also less densely packed and ordered than those of the (C16)2DTPA SAM. To understand these differences, we present density functional theory calculations that show that there are only minimal differences between the geometric and electronic structures of the two adsorbates and that the energetic difference between monodentate and bidentate binding of a gold(I) ion are surprisingly small for both adsorbates. This study leads to the conclusion that differences in intermolecular interactions within the SAM are the driving force for the difference in chelation between the two adsorbates.

Formation of self-assembled monolayers with homogeneously mixed, loosely packed alkyl groups using unsymmetrical dialkyldithiophosphinic acids.

We report the formation and characterization of self-assembled monolayers (SAMs) formed from unsymmetrical dialkyldithiophosphinic acid (R(1)R(2)DTPA) adsorbates [CH(3)(CH(2))(n)][CH(3)(CH(2))(15)]P(S)SH (n = 5, 9) on gold substrates. These SAMs were characterized using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle goniometry, electrochemical impedance spectroscopy, and atomic force microscopy. Unsymmetrical R(1)R(2)DTPA SAMs contain mixtures of bidentate and monodentate adsorbates, similar to SAMs formed from analogous symmetrical R(2)DTPAs. In unsymmetrical R(1)R(2)DTPA SAMs, however, the short alkyl substituent of the R(1)R(2)DTPA adsorbates enforces spacing between the long hexadecyl substituents, which disrupts van der Waals interactions and causes the hexadecyl groups to be loosely packed and disordered. The structure of the SAM depends on the length of the short alkyl substituent: The hexyl chains in the C(6)C(16)DTPA SAM are not long enough to stabilize the alkyl zone close to the substrate, leading to highly disordered SAMs with a low molecular packing density in which the hexadecyl chains lie down to fill the gaps between adjacent adsorbates. In contrast, the additional van der Waals interactions provided by the decyl chains of the C(10)C(16)DTPA SAM enable dense molecular packing in the alkyl zone close to the substrate. The structure of the SAM consists of a zone close to the substrate composed of a packed alkyl layer, with hexadecyl chains protruding above to form a loosely packed, disordered alkyl layer. Regardless of the structural differences between the C(6)C(16)DTPA and C(10)C(16)DTPA SAMs, both SAMs exhibit homogeneous mixing of the alkyl chains within the SAM, demonstrating that binding two different chains to a single headgroup is an effective method to prevent phase segregation.

Influence of alkyl chain length on the structure of dialkyldithiophosphinic acid self-assembled monolayers on gold.

We report the formation and characterization of self-assembled monolayers (SAMs) based on dialkyldithiophosphinic acid adsorbates {[CH(3)(CH(2))(n)](2)P(S)SH (n = 5, 9, 11, 13, 15)} on gold substrates. SAMs were characterized using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, contact angle measurements, and electrochemical impedance spectroscopy. Data show that there is a roughly 60:40 mixture of bidentate and monodentate adsorbates in each of these SAMs. The presence of monodentate adsorbates is due to the numerous and deep grain boundaries of the underlying gold substrate, which disrupt chelation. Comparing the characterization data of dialkyldithiophosphinic acid SAMs with those of analogous n-alkanethiolate SAMs shows that both SAMs follow a similar trend: The alkyl chains become increasingly organized and crystalline with increasing alkyl chain length. The alkyl groups of dialkyldithiophosphinic acid SAMs, however, are generally less densely packed than those of n-alkanethiolate SAMs. For short alkyl chains (hexyl, decyl, and dodecyl), the significantly lower packing densities cause the alkyl chains to be liquid-like and disorganized. Long-chain dialkyldithiophosphinic acid SAMs are only slightly less crystalline than analogous n-alkanethiolate SAMs.

Stretchable light-emitting electrochemical cells using an elastomeric emissive material.

Dispersing an ionic transition metal complex into an elastomeric matrix enables the fabrication of intrinsically stretchable light-emitting devices that possess large emission areas (∼175 mm(2)) and tolerate linear strains up to 27% and repetitive cycles of 15% strain. This work demonstrates the suitability of this approach to new applications in conformable lighting that require uniform, diffuse light emission over large areas.

New dialkyldithiophosphinic acid self-assembled monolayers (SAMs): influence of gold substrate morphology on adsorbate binding and SAM structure.

We report the fabrication and characterization of new self-assembled monolayers (SAMs) formed from dihexadecyldithiophosphinic acid [(C(16))(2)DTPA] molecules on gold substrates. In these SAMs, the ability of the (C(16))(2)DTPA headgroup to chelate to the gold surface depends on the morphology of the gold substrate. Gold substrates fabricated by electron-beam evaporation (As-Dep gold) consist of ∼50-nm grains separated by deep grain boundaries (∼10 nm). These grain boundaries inhibit the chelation of (C(16))(2)DTPA adsorbates to the surface, producing SAMs in which there is a mixture of monodentate and bidentate adsorbates. In contrast, gold substrates produced by template stripping (TS gold) consist of larger grains (∼200-500 nm) with shallower grain boundaries (<2 nm). On these substrates, the low density of shallow grain boundaries allows (C(16))(2)DTPA molecules to chelate to the surface, producing SAMs in which all molecules are bidentate. The content of bidentate adsorbates in (C(16))(2)DTPA SAMs formed on As-Dep and TS gold substrates strongly affects the SAM properties: Alkyl chain organization, wettability, frictional response, barrier properties, thickness, and thermal stability all depend on whether a SAM has been formed on As-Dep or TS gold. This study demonstrates that substrate morphology has an important influence on the structure of SAMs formed from these chelating adsorbates.