Self Powered and Wearable Electronic Skin

Self Powered and Wearable Electronic Skin Market Outlook

The global self-powered and wearable electronic skin market is projected to reach a value of approximately USD 7.8 billion by 2033, growing at a compound annual growth rate (CAGR) of around 17.5% from 2025 to 2033. This growth can be attributed to several factors, including the increasing demand for advanced healthcare monitoring systems, rising awareness of wearable technology applications, and ongoing advancements in materials technology such as graphene and conductive polymers. Additionally, the surge in consumer electronics and the need for enhanced human-machine interaction capabilities further drive the market. The confluence of these elements creates a strong impetus for the development of innovative solutions in the electronic skin space, set to enhance functionality across various applications, including health monitoring and prosthetics.

Growth Factor of the Market

The growth of the self-powered and wearable electronic skin market is significantly driven by the evolution of health monitoring technologies, which are increasingly integrated into everyday wearables. The rising incidences of chronic diseases necessitate continuous monitoring of vital signs, propelling the demand for sophisticated wearable devices capable of real-time data collection. Moreover, the growing trend of miniaturization in electronics is facilitating the development of thinner, more flexible electronic skins, thus improving user comfort and convenience. Another pivotal factor is the increasing investments by governments and private sectors in research and development of next-generation materials that enhance sensor performance and energy efficiency. Additionally, the expanding consumer electronics sector is also pushing the envelope for innovative applications of electronic skins in robotics and human-machine interfaces, thereby creating further market opportunities.

Key Highlights of the Market

• The market is expected to witness a CAGR of 17.5% between 2025 and 2033.
• Health monitoring applications are anticipated to dominate the market, driven by the rising demand for remote patient monitoring solutions.
• The Asia Pacific region shows significant growth potential due to rapid technological advancements and increased healthcare spending.
• Graphene-based electronic skins are gaining traction due to their superior flexibility and conductivity, making them ideal for various applications.
• Online distribution channels are expected to grow rapidly, providing consumers with easy access to the latest wearable technologies.

By Product Type

Sensors:

Sensors are a fundamental component of self-powered and wearable electronic skin, playing a crucial role in capturing various physiological signals such as temperature, pressure, and bioelectric signals. The integration of advanced materials, such as flexible electronics, enables these sensors to be lightweight and conformable to human skin, allowing for seamless monitoring. The increasing demand for health monitoring applications, particularly in remote patient care, is driving innovations in sensor technology. Furthermore, the ability to collect real-time data enhances the accuracy of health assessments and supports timely medical interventions, making sensors a pivotal segment in this market.

Displays:

Displays in wearable electronic skins are essential for providing visual feedback and enhancing user engagement. The market is witnessing advancements in display technologies that focus on flexibility and low power consumption, allowing displays to be seamlessly integrated into various wearable formats. As interactive capabilities become increasingly important in health monitoring and human-machine interfaces, the demand for high-resolution, flexible displays continues to grow. Moreover, researchers are exploring augmented reality applications that utilize these displays to provide users with an immersive experience, thus broadening the potential use cases in entertainment and gaming.

Energy Harvesters:

Energy harvesters are a vital segment in the self-powered electronic skin market, as they facilitate the sustainable operation of wearable devices without relying on traditional batteries. This technology harnesses ambient energy from the environment, such as thermal energy or kinetic energy from body movements, and converts it into usable electrical energy. With the increasing emphasis on developing eco-friendly solutions, energy harvesters are gaining traction in various applications ranging from health monitoring to smart clothing. This not only enhances the longevity of wearable devices but also aligns with consumers’ preferences for sustainable and environmentally friendly technologies.

Circuits:

Circuits are integral to the functionality of self-powered and wearable electronic skins, connecting various components and facilitating communication between sensors, displays, and energy sources. The advancement of printed and flexible circuits is revolutionizing the design of wearable devices, enabling them to be more adaptable and comfortable for users. These innovations contribute to the reduction of the overall weight and bulkiness of the devices, which is crucial for user acceptance. Furthermore, the development of circuit technologies capable of withstanding bending and stretching is vital for enhancing the durability and reliability of electronic skins in various environments.

Others:

This category encompasses various additional components and technologies that contribute to the functionality and performance of wearable electronic skins. This includes materials used in the fabrication of electronic skins, protective coatings that enhance durability, and specialty adhesives that ensure proper adhesion to the skin. The innovation in this segment is crucial for the overall efficacy of electronic skins, as these elements must work harmoniously to provide a seamless user experience. Moreover, ongoing research into incorporating smart materials that respond to environmental stimuli is poised to expand the capabilities of electronic skins further, making this segment vital for future growth.

By Application

Health Monitoring:

Health monitoring applications are at the forefront of the self-powered and wearable electronic skin market, driven by the increasing demand for continuous health assessment solutions. These applications facilitate remote patient monitoring, where devices can track vital signs such as heart rate, body temperature, and glucose levels in real-time. The ability to provide immediate feedback and alerts to medical professionals and patients significantly enhances the effectiveness of healthcare management. Additionally, the integration of artificial intelligence in data analysis is further optimizing health monitoring systems, ensuring timely interventions and personalized healthcare experiences.

Human-Machine Interface:

The human-machine interface (HMI) applications of wearable electronic skin are gaining momentum as technology continues to evolve. HMIs enable seamless interaction between users and digital devices, providing a more intuitive and engaging experience. By utilizing sensors embedded within electronic skins, users can control devices through gestures and touch sensitivity, which is especially beneficial in the context of smart homes and industrial automation. The demand for enhanced user experiences in consumer electronics and the automotive sector is driving innovation in HMI technologies, positioning electronic skins as a viable solution for future interactive systems.

Prosthetics:

The integration of electronic skin in prosthetics is revolutionizing the field, providing enhanced sensory feedback and control for users. Wearable electronic skins equipped with sensors can mimic the functionality of human skin, allowing prosthetic limbs to respond to environmental stimuli. This greatly improves the user's ability to perceive sensations like touch and temperature, leading to more natural interactions with their surroundings. As research progresses, the development of advanced materials and technologies will continue to enhance the capabilities and comfort of prosthetics, paving the way for broader acceptance and usage in the rehabilitation space.

Robotics:

Robotic applications of self-powered electronic skin are becoming increasingly essential, particularly in the realms of humanoid robots and intelligent automation. By equipping robots with electronic skin, they can gain a sense of touch, allowing them to interact with their environment more effectively and perform delicate tasks. The integration of advanced sensors and actuators into robotic systems enhances their operational capabilities and enables them to operate in unstructured environments. As industries continue to adopt automation solutions, the demand for robotic systems with human-like sensing abilities will expand, driving growth in the electronic skin market.

Others:

The "Others" category for applications encompasses various niche and emerging uses of wearable electronic skins that do not fall under the primary categories. This includes applications in the fields of entertainment, sports and fitness, and even military use, where wearable technologies can monitor performance metrics and improve training protocols. The versatility of electronic skin technology allows for innovative applications that enhance user experiences across diverse sectors. As awareness and understanding of these technologies increase, new opportunities will arise, further propelling market growth and diversification.

By Distribution Channel

Online Stores:

Online stores have emerged as a significant distribution channel for self-powered and wearable electronic skins, particularly in recent years as consumer shopping habits have shifted towards e-commerce. The convenience of online shopping allows consumers to access a broader range of products and innovations from various manufacturers without geographical constraints. Additionally, e-commerce platforms often provide extensive product information, reviews, and comparison tools, helping consumers make informed purchasing decisions. With advancements in digital marketing and targeted advertising, online retailers are effectively reaching niche markets, fueling the growth of this distribution channel.

Specialty Stores:

Specialty stores play a vital role in offering tailored products and expert knowledge about self-powered and wearable electronic skins. These retail locations focus on specific product categories, allowing them to provide in-depth insights and personalized customer service that online platforms may lack. Furthermore, specialty stores often feature the latest innovations and technologies, creating an engaging shopping experience for consumers interested in cutting-edge wearable technology. The strong emphasis on customer education and product demonstration in these stores fosters brand loyalty and encourages repeat purchases, contributing to the segment’s overall growth.

Electronic Retailers:

Electronic retailers serve as a critical distribution channel for self-powered and wearable electronic skins, providing a physical outlet for consumers to explore, test, and purchase various electronic products. These retailers often carry a wide range of brands and product types, catering to diverse consumer preferences. The advantage of electronic retailers lies in their ability to offer hands-on experiences, allowing consumers to interact with products before making a purchase decision. Additionally, promotional activities and bundled offers from electronic retailers can drive sales and encourage consumers to explore new technologies, thus enhancing the visibility of electronic skins in the market.

Healthcare Facilities:

Healthcare facilities serve as an essential distribution channel for self-powered and wearable electronic skins, particularly in the context of medical applications. Hospitals and clinics often utilize advanced wearable technologies for patient monitoring and rehabilitation, making them key buyers of electronic skin products. The integration of wearable devices into healthcare settings is driven by the need for improved patient outcomes and enhanced operational efficiencies. Suppliers often collaborate with healthcare providers to offer customized solutions that meet the specific needs of patients, thereby fostering long-term partnerships and stable demand in this segment.

Others:

The "Others" category under distribution channels includes various alternative avenues through which self-powered and wearable electronic skins are marketed and sold. This can encompass direct sales through manufacturers, participation in trade shows and exhibitions, and partnerships with other businesses or organizations that integrate wearable technology into their offerings. The increasing trend towards collaborative approaches in technology distribution allows manufacturers to tap into new customer segments and diversify their revenue streams. As awareness and demand for wearable technologies continue to grow, these alternative distribution channels will become increasingly vital in reaching potential customers.

By Ingredient Type

Graphene:

Graphene has emerged as a leading ingredient in the development of self-powered and wearable electronic skins due to its exceptional properties, including high electrical conductivity, flexibility, and mechanical strength. The incorporation of graphene into electronic skin technology enhances performance, allowing devices to maintain functionality even under deformation or strain. Moreover, the lightweight nature of graphene contributes to user comfort, making it an ideal material for wearable applications. As research progresses, advancements in graphene production techniques are expected to further drive its adoption in various electronic skin applications, paving the way for innovations in health monitoring and human-machine interfaces.

Nanowires:

Nanowires are another significant ingredient type that plays a crucial role in the functionality of self-powered and wearable electronic skins. Their unique properties enable the development of highly sensitive and efficient sensors capable of detecting minute changes in environmental conditions. The use of nanowires in electronic skins allows for improved energy harvesting capabilities, which are essential for self-powered applications. Moreover, the integration of nanowires contributes to the miniaturization of devices, ensuring that wearables remain lightweight and comfortable for users. As technology continues to advance, the potential applications of nanowires in electronic skin technology are set to expand significantly.

Conductive Polymers:

Conductive polymers are pivotal in enhancing the electrical properties of self-powered and wearable electronic skins, making them essential for various applications. These materials possess the ability to conduct electricity while maintaining flexibility and biocompatibility, making them ideal for integration in wearable devices. The versatility of conductive polymers allows for their use in sensors, actuators, and energy harvesting devices, facilitating the development of multifunctional electronic skins. As research into new formulations and processing techniques continues, the potential for innovative applications utilizing conductive polymers will grow, further propelling the market.

Silicon:

Silicon remains a widely used ingredient in the manufacturing of electronic skins, particularly in the development of integrated circuits and sensors. Its availability, cost-effectiveness, and established manufacturing processes make silicon a staple in the electronics industry. While the trend towards flexible and wearable technology is driving innovations in materials, silicon continues to provide a reliable foundation for various electronic components. The ongoing research into enhancing silicon-based materials for flexibility and durability will ensure that it remains relevant in the evolving landscape of wearable technologies.

Others:

This category encompasses various alternative ingredient types used in the development of self-powered and wearable electronic skins. It includes materials such as metal oxides, carbon nanotubes, and hydrogels that contribute to specific functionalities within electronic skins. The inclusion of diverse materials enhances the overall performance and versatility of wearable devices, allowing for unique applications across multiple sectors. As the market for wearable technology continues to grow, the exploration of novel materials and their potential applications will play a crucial role in advancing electronic skin technology.

By Region

The North American region holds a significant share in the self-powered and wearable electronic skin market, attributed to the strong presence of technology-driven companies and extensive research activities. The United States, in particular, is at the forefront of innovation, leading the development of advanced healthcare monitoring systems and wearable technologies. The region has witnessed substantial investments in R&D, driving advancements in materials and technology, which are expected to contribute to a CAGR of 16% during the forecast period. Additionally, the growing adoption of wearable devices among consumers for fitness and health tracking purposes is further propelling the market in this region.

In Europe, the market for self-powered and wearable electronic skins is poised for considerable growth, driven by increasing awareness of health and fitness, along with the adoption of advanced monitoring solutions. Countries like Germany, the UK, and France are leading the way in developing and implementing innovative health technologies. The European market is characterized by strong governmental support for research and development initiatives aimed at promoting the use of wearable technologies in healthcare settings. Together, these factors are expected to result in steady market growth, making Europe a key player in the global electronic skin market landscape.

Opportunities

The self-powered and wearable electronic skin market is poised to capitalize on numerous opportunities arising from advancements in technology and increasing demand for health monitoring solutions. As consumers become more health-conscious, there is a growing demand for devices that enable real-time health tracking and data analysis. This trend is encouraging manufacturers to invest in R&D to develop next-generation electronic skins that offer enhanced functionalities and integrations with smartphone applications and cloud computing solutions. Moreover, the potential for collaboration between healthcare providers and technology companies can lead to innovative solutions tailored to specific patient needs, further driving market growth.

Additionally, the market is likely to benefit from the rising interest in the Internet of Things (IoT) and smart technologies. The integration of self-powered electronic skins into IoT ecosystems allows for seamless data exchange and advanced analytics, enabling users to make informed decisions about their health and fitness. Furthermore, as broader adoption of smart home devices continues, electronic skins can be integrated into various applications, ranging from personal wellness monitoring to enhanced human-machine interactions. This convergence of sectors presents a significant opportunity for the self-powered and wearable electronic skin market to expand its reach and establish new revenue streams.

Threats

Despite the promising growth of the self-powered and wearable electronic skin market, several threats could hinder its progress. One of the primary concerns is the rapid pace of technological advancements, which can create challenges for manufacturers to keep up with evolving consumer expectations and competition. As new products and features emerge, there is a risk of obsolescence for existing technologies, prompting companies to invest heavily in R&D to remain relevant. Furthermore, the market is also susceptible to economic fluctuations, which can affect consumer purchasing power and limit investments in wearable technologies. Additionally, concerns surrounding data privacy and the security of personal health information may deter consumers from adopting electronic skin solutions, impacting overall market growth.

Moreover, the high costs associated with developing and producing self-powered and wearable electronic skins may pose a restraint for smaller companies looking to enter the market. The need for specialized materials and advanced manufacturing processes can lead to increased production costs, limiting the ability of new entrants to compete with established players. Additionally, regulatory challenges in different regions regarding the approval and commercialization of wearable health monitoring devices may slow down market entry for innovative products. As these factors evolve, stakeholders in the electronic skin market will need to develop strategic approaches to mitigate risks and navigate potential barriers.

Competitor Outlook

• MC10 Inc.
• Xsensio
• NanoSkin Technologies
• Sunpower, Inc.
• University of California, Berkeley
• Wearable X
• Sensoria Inc.
• Adidas AG
• Philips Healthcare
• Google Inc.
• Apple Inc.
• Reebok International Ltd.
• Proteus Digital Health, Inc.
• BioBeat Technologies Ltd.
• Vestech Co., Ltd.

The competitive landscape of the self-powered and wearable electronic skin market is characterized by a mix of established players and emerging startups. Major companies are increasingly focusing on strategic collaborations, acquisitions, and partnerships to enhance their product offerings and expand their market reach. Industry leaders are investing heavily in research and development to explore innovative materials and advanced technologies that can provide users with enhanced functionalities and improved performance. With the growing awareness of health monitoring and wearable technologies, competition is expected to intensify as new entrants seek to carve out their niches in this dynamic market.

MC10 Inc. is one of the prominent players in this market, known for its innovative approach to flexible electronics. The company has developed a unique electronic skin technology that allows for the integration of sensors and displays in a conformable format that adheres directly to the skin. This technology has significant potential in health monitoring applications, providing real-time data to users. Additionally, MC10's partnerships with key healthcare organizations bolster its position as a leader in the sector, enabling them to push the boundaries of wearable technology.

Another key competitor in the market is Philips Healthcare, which has established a solid reputation for its contributions to healthcare technology and innovation. The company is actively involved in the development of wearable health monitoring devices that incorporate self-powered electronic skin technology. With a strong portfolio of products aimed at enhancing patient care and monitoring, Philips Healthcare is positioning itself as a forward-thinking leader in the electronic skin market. Their ongoing commitment to research and development ensures that they remain competitive in a rapidly evolving landscape.

• 1 Appendix

  • 1.1 List of Tables
  • 1.2 List of Figures

• 2 Introduction

  • 2.1 Market Definition
  • 2.2 Scope of the Report
  • 2.3 Study Assumptions
  • 2.4 Base Currency & Forecast Periods

• 3 Market Dynamics

  • 3.1 Market Growth Factors
  • 3.2 Economic & Global Events
  • 3.3 Innovation Trends
  • 3.4 Supply Chain Analysis

• 4 Consumer Behavior

  • 4.1 Market Trends
  • 4.2 Pricing Analysis
  • 4.3 Buyer Insights

• 5 Key Player Profiles

  • 5.1 Xsensio
    • 5.1.1 Business Overview
    • 5.1.2 Products & Services
    • 5.1.3 Financials
    • 5.1.4 Recent Developments
    • 5.1.5 SWOT Analysis
  • 5.2 Adidas AG
    • 5.2.1 Business Overview
    • 5.2.2 Products & Services
    • 5.2.3 Financials
    • 5.2.4 Recent Developments
    • 5.2.5 SWOT Analysis
  • 5.3 MC10 Inc.
    • 5.3.1 Business Overview
    • 5.3.2 Products & Services
    • 5.3.3 Financials
    • 5.3.4 Recent Developments
    • 5.3.5 SWOT Analysis
  • 5.4 Apple Inc.
    • 5.4.1 Business Overview
    • 5.4.2 Products & Services
    • 5.4.3 Financials
    • 5.4.4 Recent Developments
    • 5.4.5 SWOT Analysis
  • 5.5 Wearable X
    • 5.5.1 Business Overview
    • 5.5.2 Products & Services
    • 5.5.3 Financials
    • 5.5.4 Recent Developments
    • 5.5.5 SWOT Analysis
  • 5.6 Google Inc.
    • 5.6.1 Business Overview
    • 5.6.2 Products & Services
    • 5.6.3 Financials
    • 5.6.4 Recent Developments
    • 5.6.5 SWOT Analysis
  • 5.7 Sensoria Inc.
    • 5.7.1 Business Overview
    • 5.7.2 Products & Services
    • 5.7.3 Financials
    • 5.7.4 Recent Developments
    • 5.7.5 SWOT Analysis
  • 5.8 Sunpower, Inc.
    • 5.8.1 Business Overview
    • 5.8.2 Products & Services
    • 5.8.3 Financials
    • 5.8.4 Recent Developments
    • 5.8.5 SWOT Analysis
  • 5.9 Vestech Co., Ltd.
    • 5.9.1 Business Overview
    • 5.9.2 Products & Services
    • 5.9.3 Financials
    • 5.9.4 Recent Developments
    • 5.9.5 SWOT Analysis
  • 5.10 Philips Healthcare
    • 5.10.1 Business Overview
    • 5.10.2 Products & Services
    • 5.10.3 Financials
    • 5.10.4 Recent Developments
    • 5.10.5 SWOT Analysis
  • 5.11 NanoSkin Technologies
    • 5.11.1 Business Overview
    • 5.11.2 Products & Services
    • 5.11.3 Financials
    • 5.11.4 Recent Developments
    • 5.11.5 SWOT Analysis
  • 5.12 BioBeat Technologies Ltd.
    • 5.12.1 Business Overview
    • 5.12.2 Products & Services
    • 5.12.3 Financials
    • 5.12.4 Recent Developments
    • 5.12.5 SWOT Analysis
  • 5.13 Reebok International Ltd.
    • 5.13.1 Business Overview
    • 5.13.2 Products & Services
    • 5.13.3 Financials
    • 5.13.4 Recent Developments
    • 5.13.5 SWOT Analysis
  • 5.14 Proteus Digital Health, Inc.
    • 5.14.1 Business Overview
    • 5.14.2 Products & Services
    • 5.14.3 Financials
    • 5.14.4 Recent Developments
    • 5.14.5 SWOT Analysis
  • 5.15 University of California, Berkeley
    • 5.15.1 Business Overview
    • 5.15.2 Products & Services
    • 5.15.3 Financials
    • 5.15.4 Recent Developments
    • 5.15.5 SWOT Analysis

• 6 Market Segmentation

  • 6.1 Self Powered and Wearable Electronic Skin Market, By Application
    • 6.1.1 Health Monitoring
    • 6.1.2 Human-Machine Interface
    • 6.1.3 Prosthetics
    • 6.1.4 Robotics
    • 6.1.5 Others
  • 6.2 Self Powered and Wearable Electronic Skin Market, By Product Type
    • 6.2.1 Sensors
    • 6.2.2 Displays
    • 6.2.3 Energy Harvesters
    • 6.2.4 Circuits
    • 6.2.5 Others
  • 6.3 Self Powered and Wearable Electronic Skin Market, By Ingredient Type
    • 6.3.1 Graphene
    • 6.3.2 Nanowires
    • 6.3.3 Conductive Polymers
    • 6.3.4 Silicon
    • 6.3.5 Others
  • 6.4 Self Powered and Wearable Electronic Skin Market, By Distribution Channel
    • 6.4.1 Online Stores
    • 6.4.2 Specialty Stores
    • 6.4.3 Electronic Retailers
    • 6.4.4 Healthcare Facilities
    • 6.4.5 Others

• 7 Competitive Analysis

  • 7.1 Key Player Comparison
  • 7.2 Market Share Analysis
  • 7.3 Investment Trends
  • 7.4 SWOT Analysis

• 8 Research Methodology

  • 8.1 Analysis Design
  • 8.2 Research Phases
  • 8.3 Study Timeline

• 9 Future Market Outlook

  • 9.1 Growth Forecast
  • 9.2 Market Evolution

• 10 Geographical Overview

  • 10.1 Europe - Market Analysis
    • 10.1.1 By Country
      • 10.1.1.1 UK
      • 10.1.1.2 France
      • 10.1.1.3 Germany
      • 10.1.1.4 Spain
      • 10.1.1.5 Italy
  • 10.2 Asia Pacific - Market Analysis
    • 10.2.1 By Country
      • 10.2.1.1 India
      • 10.2.1.2 China
      • 10.2.1.3 Japan
      • 10.2.1.4 South Korea
  • 10.3 Latin America - Market Analysis
    • 10.3.1 By Country
      • 10.3.1.1 Brazil
      • 10.3.1.2 Argentina
      • 10.3.1.3 Mexico
  • 10.4 North America - Market Analysis
    • 10.4.1 By Country
      • 10.4.1.1 USA
      • 10.4.1.2 Canada
  • 10.5 Middle East & Africa - Market Analysis
    • 10.5.1 By Country
      • 10.5.1.1 Middle East
      • 10.5.1.2 Africa
  • 10.6 Self Powered and Wearable Electronic Skin Market by Region

• 11 Global Economic Factors

  • 11.1 Inflation Impact
  • 11.2 Trade Policies

• 12 Technology & Innovation

  • 12.1 Emerging Technologies
  • 12.2 AI & Digital Trends
  • 12.3 Patent Research

• 13 Investment & Market Growth

  • 13.1 Funding Trends
  • 13.2 Future Market Projections

• 14 Market Overview & Key Insights

  • 14.1 Executive Summary
  • 14.2 Key Trends
  • 14.3 Market Challenges
  • 14.4 Regulatory Landscape

Segments Analyzed in the Report

The global Self Powered and Wearable Electronic Skin market is categorized based on

By Product Type

• Sensors
• Displays
• Energy Harvesters
• Circuits
• Others

By Application

• Health Monitoring
• Human-Machine Interface
• Prosthetics
• Robotics
• Others

By Distribution Channel

• Online Stores
• Specialty Stores
• Electronic Retailers
• Healthcare Facilities
• Others

By Ingredient Type

• Graphene
• Nanowires
• Conductive Polymers
• Silicon
• Others

By Region

• North America
• Europe
• Asia Pacific
• Latin America
• Middle East & Africa

Key Players

• MC10 Inc.
• Xsensio
• NanoSkin Technologies
• Sunpower, Inc.
• University of California, Berkeley
• Wearable X
• Sensoria Inc.
• Adidas AG
• Philips Healthcare
• Google Inc.
• Apple Inc.
• Reebok International Ltd.
• Proteus Digital Health, Inc.
• BioBeat Technologies Ltd.
• Vestech Co., Ltd.