Textiles are an integral part of our daily lives, from the clothes we wear to…
With the accelerated growth of the 3D printing market, the textile industry has started to innovate and manufacture in various ways using 3D printing technology, such as 3D printed textiles, apparel, fashion accessories, and footwear. Compared to traditional textiles, smart textiles require higher manufacturing technology，3D printing technology can solve this problem at some level by directly printing in three dimensions using materials with smart properties to manufacture smart textiles. Research on the application of 3D printing technology in the field of smart textiles can provide new ideas to promote the development, design, and exploitation of the smart textile industry.
Classification of Smart Textiles and Their Applications
Definition of Smart Textiles
Smart textiles are new textiles that incorporate material, biological, chemical, electronic information, and other technologies into textiles so that they can sense, react, adjust or adapt to different stimuli (light, temperature, humidity, solvents, electricity, magnetism, etc.), as well as continuing their own properties. It can be divided into two categories: one is “passive” smart textiles, which have the ability to change their performance after being stimulated by the environment. For example, shape memory textiles, hydrophobic or hydrophilic textiles, etc. belong to this category. Another category of “active” smart textiles is the ability to transform content parameters into transmission information by means of sensors and actuators. These “active” smart textiles can sense different environmental signals such as temperature, light intensity, and pollution, and provide feedback to the environmental signals using various fabric-based, flexible, and miniaturized actuators, including textile displays, micro-vibration devices, and light-emitting diodes. With the advancement in technologies such as nanofiber nonwovens, conductive fibers, plastic optical fibers, graphene, carbon nanotubes, small electronic components and sensors, and micro-thin batteries, the market growth for smart textiles has been given a huge boost.
Classification of Smart Textiles
Smart textiles are widely used in transportation, energy and medical fields, protection, security, communication and other electronic products, and can be classified into smart color change, temperature control, shape memory, waterproof and moisture permeable, active textiles and smart electronic textiles according to the different functions.
Smart color-changing textiles
Smart color-changing textiles are textiles that can show different colors with changes in external environmental conditions, such as light, temperature, pressure, etc. These smart textiles mainly include photochromic textiles, thermochromic textiles, electrochromic textiles, thermochromic textiles, pressure-chromic textiles, and moisture-chromic textiles. Photochromic textiles produce a reversible transformation between two forms with different absorption spectra by light irradiation, mainly in the form of color change according to the light source, and the original color can be restored after the light source disappears. Thermochromic textiles can change their color according to the change of the surrounding temperature, and their color change is mainly based on the pH change mechanism and the electron gain/loss mechanism. Electrochromic textiles mainly use a flat sandwich structure or linear structure, in which various fiber electrodes are wrapped together to achieve the color change effect of fibers by adjusting the doping composition and ratio of color-changing materials or changing the chemical structure of a single electrochromic material. Electrothermal color-changing textiles refer to the reversible color change of certain fiber materials due to Joule heat under the effect of alternating positive and negative voltage. This type of textile is an intelligent color-changing textile that combines electrochromic and thermochromic effects, the fundamental principle of which is thermochromic. Piezoceramic textiles change color by sensing the area of the fabric under pressure through a matrix formed by the interweaving of conductive fibers in warp and weft.
Smart Temperature-controlled textiles
Heat transfer between the human body and the environment is highly dependent on the synergistic effects of ambient temperature, air movement, average radiant heating, relative humidity, and clothing textiles. Traditional textile materials including cotton, polyester, wool and nylon ,all have disadvantages in temperature control. For example, when cotton is used to prevent heat loss in cold winter, increasing the thickness is the only way, however, the performance of warmth is limited. In the hot summer, cotton also cannot block infrared radiation. Therefore, the development of intelligent temperature-controlled textiles enables the textiles to interact with the human body to control energy output and regulate body temperature. Smart temperature-controlled textiles can be divided into two categories according to their mechanisms: the first category refers to textiles that can sense and respond to environmental stimuli without input power. Its physical or chemical structure can change in response to changes in ambient temperature. For example, phase change materials, which can absorb or release heat in response to environmental changes, are one of the main materials for intelligent temperature-controlled textiles . Textiles fused with phase change materials can form an energy regulation system, which is designed to keep the human body temperature at a constant temperature, so that people do not feel too cold or too hot, and reduce the body’s energy output between the hot and cold poles. The second category is textiles that can convert body heat into electricity. For example, thermoelectric (TE) materials based on the Seebeck effect are used in the textile field and have demonstrated their great potential. TE materials use this effect to convert high entropy energy directly into electricity. In addition, TE materials can also convert electrical energy into thermal energy for cooling or heating.
Shape-memory textiles are textiles with excellent properties such as shape memory, high recovery rate, impact resistance, and good adaptability under external conditions such as temperature, pH, electricity, light, magnetic field, and solvents by placing materials with shape memory function in them through weaving or finishing. Shape-memory textiles can be divided into alloys and polymers by material. Shape-memory alloys are special metallic materials that can recover their original shape after being given a certain shape by appropriate heating, irradiation, or chemical treatment. Shape memory polymers, as a class of polymeric materials, are widely used because of their wide range of temperature memory options, lightweight, easy raw material and processing, and large recoverable shape variables. Shape memory polymers can be manufactured into memory fibers, and then woven from the fibers into textiles with memory function; can also be made into finishing solution, post-finishing of ordinary fabrics, so that textiles with shape memory function. After the shape memory post-finishing textiles, its memory performance will slowly weaken with the increase of washing times, or even disappear; while the shape memory fibers woven from the textiles, its memory characteristics, and the nature of the fiber itself, some materials can permanently maintain the shape memory characteristics.
Waterproof and moisture-permeable textiles
Waterproof and breathable textiles, also known as “breathable textiles”, are textiles that are not wetted by water under a certain water pressure, making them water-repellent, and at the same time, sweat emitted by the human body can be conducted to the outside of the textile in the form of water vapor, so making people feel uncomfortable. The principle of water-repellent and moisture-permeable textiles is the diffusion of gas molecules from high to low concentrations through the yarn gap. It mainly includes the following four types: high-density textiles are made of combed high-count cotton yarn or ultra-fine synthetic fibers with a particularly dense texture, the use of changing the fabric structure to achieve the purpose of waterproof and moisture permeable; microporous membrane waterproof and moisture permeable textiles use the difference between the diameter of water droplets and the diameter of water vapor molecules to play a waterproof and moisture-proof role; non-porous membrane waterproof and moisture-proof textiles use molecular hydrophilicity to increase the surface of the waterproof membrane Intelligent waterproof and moisture permeable textiles refers to the fabric can automatically adjust the level of moisture permeability according to different environmental characteristics, such as high temperature fabric through high moisture permeability to achieve excellent heat dissipation and sweating effect, and low temperature fabric through low moisture permeability to reduce heat dissipation to enhance warmth.
Smart active textiles
Smart active textiles change their structural shape in response to applied stimuli such as temperature, pressure, electric current, light, humidity, and solvents to produce actuation, sensing, color change, and energy harvesting. With the advantages of high stress, high adaptability, high peak output rate, and stable mechanical properties, they are now more frequently used in soft robots, wearable electronic devices, dynamic camouflage, and biomedical applications. While the traditional textile manufacturing hierarchy is based on fiber material, yarn structure, and textile form, smart active textiles are developed based on the structural level of textiles. By adding active materials such as hydrogel, carbon nanotubes, graphene, and dual chips to the fiber composition, the basic characteristics of textile fiber materials are maintained and new active features are added. The yarn structure is the second step of the smart active textile hierarchy, which modifies the mechanical properties of the original fiber material by applying pre-stress and constraint. The main structural deformations of active yarns are twisted spiral structure, porous structure, cross-linked mesh structure, sandwich structure, and hybrid coaxial structure. The parameters involved in this process include the number of filaments in bundles and the twist applied per unit length, which further adjusts the bending stiffness, breaking strength, and strain stretch rate of the yarn. Finally, the mechanical properties of the active fibers and yarns can be further adjusted by using manufacturing processes such as weaving, knitting, or braiding to make the active yarns into textile forms.
Smart e-textiles combine textiles with electronic information technology by embedding sensors and communication devices in textiles, and then collecting and analyzing data generated by devices in textiles and giving feedback through technologies such as the Internet of Things, artificial intelligence and computers . Smart e-textiles consist of electronic components such as distributed processing units, various sensors, human-computer interaction devices and power supply systems, etc. There are three main ways to implement these electronic components in smart textiles: the first way is to integrate existing electronic components into textiles. The advantage is that the production process is relatively simple, but if the electronic components used are too large, there are also problems that affect the user’s use and washing. The second way is to use textile materials and textile manufacturing technology to produce electronic components. Although the process of integration is easier, the textile materials and textile manufacturing technology can produce a limited type of electronic components. The third implementation is to produce and use fibers to provide some electronic functionality.
3D printing technology classification and characteristics
Definition of 3D printing
3D printing, also known as additive manufacturing, is a technology that uses 3D digital model files as the basis for constructing objects by printing layer by layer using adhesive materials such as powdered metals or plastics. The 3D printing process consists of three main steps: modeling, printing, and post-processing. CAD design is performed by design software or 3D scanner, digital files are transferred to the 3D printer system, relevant parameters are set to start printing, and post-processing of the printed object using grinding, dyeing, and pasting may be required after printing is completed. The traditional processing technology is mainly mechanical processing by cutting or cutting materials, while 3D printing is the opposite of traditional cutting processing by stacking layers. Compared with traditional machining, the advantages of 3D printing are faster processing of complex parts, improved design performance of functional products, faster product design process, integrated molding to reduce the assembly process, simpler manufacturing tools, increased energy savings, and reduced production costs of multiple products in a common line. Therefore, 3D printing has been used in the fields of biomedical, aerospace, cultural creativity and digital entertainment, industrial manufacturing, and construction engineering, and even has a place in the field of education.
Technology classification of 3D printing
3D printing technology is widely used in molding processes including light-curing molding (SLA), selective laser sintering (SLS), fused deposition molding (FDM), selective laser melting (SLM), laser near net molding (LENS), electron beam melting molding (EBM), layered solid manufacturing (LOM), multi-head spray technology (PolyJet), adhesive jetting ( Binder Jetting), etc. In the textile and apparel industry, FDM and SLS technologies are the most used, in addition to SLA, PolyJet, Binder Jetting, and other technologies. The different ways of molding process can be divided into 7 types, as shown in Table 1. Different 3D printing technologies use different materials, FDM mainly uses thermoplastic polymers for printing, such as ABS, PLA, PC, TPU, PVC, PPS, etc. SLS and SLA are theoretically the same, but the difference is that SLS uses a laser to sinter powder, such as nylon powder, metal powder, etc. There are also various types of materials such as plastics, metals, ceramics, glass, paper, wood, ingredients, coconut shells, wool, linen, etc. used for manufacturing. PLA and TPU are thermoplastics with good flexibility, corrosion resistance, and abrasion resistance, and Bentley is Acrylonitrile Butadiene Styrene manufactured by Orbi-Tech. According to recent studies, natural and synthetic fibers themselves can be used as 3D printing materials as material development continues. In 3D printed textile manufacturing, the physical properties that need to be focused on are softness. In addition, the basic required properties of textile materials such as tensile strength, abrasion resistance, breathability, etc. must be satisfied.
Technical Classification and Characteristics of 3D Printing
|Material Form |
|Manufacturing Process||Process Classification|
|Liquid Material||Light Curing Molding||Point-by-point Curing（SL LTP BIS）|
|Holographic Interference Curing（HIS）|
|Electric casting||Electric casting(ES) |
Thin layer material
|Hot melt adhesive bonded thin material||Hot melt adhesive bonded thin material (LOM) |
|Light bonded thin material||Light bonded thin material (SFP)|
|Hot melt cooling||Laser sintering and melting (SLS, GPD, SLM, EBM)|
|Adhesive bonding powder particles||Adhesive bonding powder particles by a binder (3DP, SF, TSF)|
Advantages of 3D printed smart textiles
3D printing technology opens up new paths and offers many new possibilities for the efficient manufacturing of smart textiles. It simplifies traditional manufacturing methods and reduces the complexity of manufacturing through multiple molding processes. Compared to conventional manufacturing, 3D printing has five key advantages in the field of smart textiles: cost, speed, innovation, quality, and impact.
Significant reduction in manufacturing costs
3D-printed smart textiles can be prototyped or fabricated directly without the use of tools and molds, which can significantly shorten the product prototype cycle and save on tooling costs. Since the manufacturing process is done independently by 3D printers, there is no need to purchase various machines, which also eliminates some of the equipment purchase and maintenance costs. Moreover, the manufacturing speed is very fast, from the CAD digital model to the production completion is much faster than the traditional processing and molding methods, when using 3D printing technology to manufacture smart textiles, because the material is added layer by layer in a controlled manner, reducing the material waste, saving both time and economic costs. In addition, 3D printing shortens the supply chain and eliminates the need for inventory, storage, packaging, and transportation, which also reduces costs in comparison.
The manufacturing process is effectively simplified
The production of smart textiles requires solving many problems, such as using unconventional yarns for weaving, reducing damage to warp and weft yarns during the weaving process, and maintaining the formability of specially structured fabrics. Compared with traditional manufacturing, 3D printing technology has greatly reduced the manufacturing process and manufacturing difficulties, mainly in terms of faster product design, less redundancy in integrated manufacturing, and simpler manufacturing tools, both for printing yarns and textile forms.
Combination of multiple materials
Part of the functionality of smart textiles is reflected in the use of smart fiber materials, that is, in order to create smart fibers will have different properties of materials combined into a single structure of fibers, while traditional machines in the fabric forming process are not easy to integrate a variety of materials for weaving. In other fields, there are a variety of materials for mixed injection molding applications, but the cost is high and the quality of molding is uneven. Unlike 3D printing technology, it is possible to mix different materials on the same machine, which provides innovative possibilities for the development of new functions in smart textiles.
Improving the quality of fabric performance
3D printing technology enhances the performance of the fabric from two aspects: first is the printing material, through the use of materials with special properties for the manufacture of fabrics, the excellent performance of the material directly affects the performance properties of the fabric. The second is the printing structure, the fabric printing structure by changing the gap between the warp and weft of the yarn, the thickness, and the arrangement of the way to show different performance quality. In addition, in the traditional manufacturing process, due to the limitations of manufacturing tools and process methods, complex structures and too curved and twisted surfaces are difficult to process, in contrast, 3D printing manufacturing has the advantage of achieving any complex shape because the technology is not subject to the technical limitations of the traditional manufacturing process.
Achieve sustainable manufacturing
The environmental pollution caused by the traditional textile industry mainly involves the processes of raw material processing, textile production, dyeing, and finishing, such as the large amount of noise generated by the equipment, the wastewater caused by resizing, boiling, bleaching and washing, the large amount of energy consumed in the process of heating the equipment, and the waste generated in the process of reducing the material manufacturing, all of which can cause environmental pollution. 3D printing is a one-piece additive manufacturing technology, which reduces the manufacturing cycle of textiles and basically does not produce waste gas and wastewater, and some of the recovered waste can be recycled.
Types of applications for 3D printing technology in the field of smart textiles
Smart textiles can contain optical fibers, phase change materials, chemicals, or other electronic components that add new functions to ordinary textiles. More and more textile materials are trying to use 3D printing technology to directly create smart textiles with complex functions. Current research is focused on conductive, shape memory, temperature regulation, and flexible electronic components.
3D printing of smart conductive textiles
The most common method of developing conductive textiles is to attach conductive materials to the surface of the fabric, which can be achieved by lamination, coating, printing, spraying, ion plating, chemical plating, vacuum metallization, cathodic sputtering, and chemical vapor deposition, etc. 3D printers are capable of printing precisely the defined shapes. In this way, conductive yarns or coatings can be connected, especially with leadless SMD (surface-mounted device) components. At the same time, 3D printing allows the structure of electronic components to be adjusted to achieve the most suitable structural state with the fabric. Grimmelsmanna et al. from the University of Applied Sciences in Bielefeld, Germany, used 3D printing technology to directly print on a fabric containing circuit paths woven using conductive Shieldex yarns so that the 3D printed objects were connected as conductive wires to small electronic components, thus allowing the textile to emit light, as shown in Figure 1. As a textile substrate, a single-sided crocheted knitted fabric with a texture effect and a relatively compact and uniform surface was selected to enable the 3D printed material to better adhere to the fabric. The developer designed an SMD-LED electronic component, which was fabricated on the surface of the textile substrate using FDM technology. The black conductive part is mainly used for the electrical connection and is made of Proto-Pasta conductive PLA filament at an extruder temperature of 207 °C and a print bed temperature of 60 °C. The layer height is 0.2 mm and the structure is filled. The white part is the normal PLA filament, which serves as a fixation and connection. The black filament with conductive properties is connected to the Shields yarn to light up the LEDs on the textile. 3D printed parts act as series resistors to protect the LEDs from excessive application voltages that can affect their normal operation. When the internal resistance is low, the brightness of the LEDs is lower because the LEDs and the 3D printed parts are connected to the series resistor to work as voltage dividers and the voltage drop is higher at higher resistances.
printed smart temperature-controlled textiles
There are various types of smart textiles with temperature regulation, such as the most common temperature and humidity regulation textiles currently available in the market, which are used to reduce body temperature by removing excess moisture. However, these textiles can only be triggered when the air between the body and the fabric is at a high humidity level, which limits their application at low humidity levels. There are other temperature control techniques, including cold pocket textiles with phase change materials, air-cooled textiles, and liquid-cooled textiles, but all have their limitations as well. Researchers have done a lot of work in developing thermoregulated textiles to solve such problems. A composite material with boron nitride nanosheets (BNNSs) embedded in a polyvinyl alcohol (PVA) polymer matrix was 3D printed at the University of Maryland to make smart temperature-controlled textiles that can bring down the body temperature rapidly, as shown in Figure 2. BNNSs have a two-dimensional structure and an in-plane thermal conductivity of up to 2,000 W/(m-K). In order to utilize the in-plane thermal properties of BNNSs, the sheets must have good alignment orientation and uniform dispersion. Uniform dispersion can be achieved because BNNSs can promote structural stabilization by absorbing polymers when sonicated in a PVA solution. Also, during fiber printing and further hot drawing processing, nanocomposite fibers were introduced by uniaxial extensional flow in which BNNSs formed well-aligned orientations, resulting in energy paths for phonon heat transfer. The highly oriented and interconnected nature of the BNNSs provides additional thermal pathways, which effectively improves the thermal performance of the a-BN/PVA composite fibers. a-BN/PVA textiles can release additional heat generated by the human body along the fibers. The textiles release the additional heat generated by the human body along the fibers into the surrounding environment, thus providing a thermally comfortable microclimate for cooling the human body.
3D-printed shape memory textiles
Shape-memory polymer is a polymer that remembers its original shape, changes its shape under certain conditions, and returns to its original shape by applying stimuli such as heat, electricity, and magnetic fields. Shape memory polymers are most commonly used in polylactic acid (PLA), which is also a material commonly used in 3D printing, and therefore can be produced by 3D printing technology. The current research on the use of 3D printing technology to print shape-memory polymers is mainly related to two aspects of the material, one is the use of 100% pure PLA as the shape-memory polymer, but since PLA material can be extended up to 10% , the structure needs to be designed to overcome this limitation before printing. This problem was solved by Langford et al. using a herringbone origami structure, as shown in Figure 3. Figure 3(a) shows a 3D-printed object with a herringbone origami structure. Figure 3(b) shows that when folded, the volume of the object becomes smaller. When unfolded, the volume of the object becomes larger, but a few tiny cracks appear on the object, as shown in Figure 3(c). The usual constant recovery rate of PLA filament is about 61%, while the recovery rate of herringbone origami structure is increased to about 96%. Another category is 3D printing using PLA composites. guido Ehrmann, Andrea Ehrmann, using an FDM 3D printer, formed a solid mixture by mixing 80% PLA with 20% Fe₃O₄ and crushing it, then extruded it in a twin-screw extruder A bone trabecular porous structure was printed , as shown in Figure 4. By applying an alternating magnetic field of 30 kHz, more than 95% shape recovery was achieved after only 14 to 24 s. In addition to these possibilities, PLA can be mixed with other polymers to create objects with recovery properties. For example, the addition of hydroxyapatite (HAP), carbon fiber, barium titanate, and polyester amide (PEA) to PLA can have an impact on the recovery rate depending on the dose added, the setting of the printing parameters, and the external factors imposed to bring about shape recovery. These 3D-printed shape-memory polymers can be used to make shape-memory fabrics for use in smart textiles.
3D-printed smart e-textiles
Smart e-textiles integrate electronic components such as sensors, microcontrollers, actuators, connection devices, and energy sources. Traditional electronic components are mostly made of metal, plastic, and other materials, which are prone to irreversible deformation when bending, twisting, stretching and other situations occur, thus affecting the normal function of electronic components, but the use of flexible materials can make up for the above problems. These flexible electronic components can not only provide portable functions for people’s daily life but also can be used to monitor the health information of the human body due to their ability to interface with human skin. However, the traditional processing technology of flexible electronic components has limitations for the processing of electronic components with complex functional structures. Therefore, 3D printing is attracting attention as a 3D rapid prototyping process. At present, various 3D printing technologies have been widely used for structural electronic devices, and more and more flexible materials have been applied to 3D printing technologies in order to increase the adaptability to different functional requirements of products. For example, Yang Hui et al  used the chemical reaction of PCL10K and isocyanic ethyl methacrylate to synthesize polycaprolactone (PCL), which can be used as a flexible material for 3D printing. Polycaprolactone (PCL) was printed into a flexible device by a commercial SLA printer and coated with conductive materials, such as silver nanoparticles or carbon nanotubes (CNTs), to form a 3D printed flexible electronic device with shape memory properties, as shown in Figure 5. Among them, the device in Fig. 5(a) consists of a 3D shape-memory polymer printed object. Figure 5(b) shows a flexible electrical temperature sensor fabricated by adding silver nanoparticles to the surface of the 3D printed object with shape memory properties by a sintering process at room temperature. In Fig. 5(c), when the flexible electric temperature sensor encounters a temperature rise, its shape changes from an open circuit to a closed circuit and lights up a light-emitting diode. The flexible sensor with shape memory behavior printed using 3D printing technology not only gives new functions to electronic devices but also plays an important role in improving product quality while changing the way people interact with electronic devices.
Development Trend of 3D Printing Smart Textiles
By applying 3D printing technology to smart textiles, the exploration of new materials, material combinations, blended yarns, and basic fabric component processing, including new fibers, yarn forms, and fabric structures, will enter a whole new field. A wide range of applications can be achieved in terms of protective functions, comfort and health care, easy-care performance, appearance and form, ease of use performance, and environmental characteristics. Currently, there are three technological applications of 3D printed smart textiles: the most common one is 3D printing directly on textiles, which can add new functions to the existing textiles. The focus of this technology is the adhesion between textiles and 3D printing materials. The degree of adhesion of different materials on the fabric, in addition to the heating properties of the two materials, is also related to the setting of printing parameters, such as printing temperature, printing speed, filling rate, alignment angle, etc. Based on the combination of soft and comfortable textile substrates and hard materials, these products will be more widely used in medical rehabilitation and safety protection in the future. The second aspect is to 3D print different textile structures, so that they have some intelligent functions, and will be widely used in robotics, clothing, construction, and other fields. The third aspect is the use of flexible materials for 3D printing, the development of flexible materials is still in its infancy, with the rapid development of elastic materials in the future, 3D printing of smart textiles can provide good breathability and moisture permeability while giving multiple functions. Both direct 3D printing on textiles and structural printing of smart textiles using different composite materials are expected to be commercially produced in large volumes in the future.
3D printing is a technology for creating solid models based on a 3D digital model with a computer-controlled accumulation of discrete materials layer by layer. Although most 3D printers work according to such working principles and processes, different 3D printing types have different technical limitations. The main types of materials used in 3D printing are liquid materials, solid materials, and powder materials, and the process of printing with the same material may be different, and the same powder material is used for 3D printing, but the SLS process requires the powder to be The SLS process requires preheating of the powder to reduce deformation and sticky powder during the printing process, while the BJ process does not require the powder preheating step. In addition, some technologies choose to add new components with different properties to the printed material in order to give special functions to the textile, and when printing with new materials, parameters such as printing temperature and printing speed need to be reset. 3D printing process structures mostly require post-processing to create smart textiles with good surface quality, mechanical properties, and functionality. Post-processing mainly includes the removal of support structures, polishing, coloring, enhanced forming strong, long-lasting preservation treatment, and surface coating. Although post-processing makes up for the lack of printed models, it also increases the operation process and production time. At present, 3D-printed smart textiles have been rapidly developed and improved, but there are certain defects and areas for improvement in the stability of the printing process, the precision of molding, finishing, and post-processing. In addition, the 3D printing smart textile industry lacks coordinated and stable development, and there is no complete industry chain or industry system, including perfect suppliers, a service provider system, a good market platform, etc. There is still a large upside in technology research and development and technology promotion.