Electricity-Driven Strategies for Bioinspired Multifunctional Swimming Marangoni Robots Based on Super-Aligned Carbon Nanotube Composites.

Marangoni actuators that are propelled by surface tension gradients hold significant potential in small-scale swimming robots. Nevertheless, the release of "fuel" for conventional chemical Marangoni actuators is not easily controllable, and the single swimming function also limits application areas. Constructing controllable Marangoni robots with multifunctions is still a huge challenge. Herein, inspired by water striders, electricity-driven strategies are proposed for a multifunctional swimming Marangoni robot (MSMR), which is fabricated by super-aligned carbon nanotube (SACNT) and polyimide (PI) composite. The MSMR consists of a Marangoni actuator and air-ambient actuators. Owing to the temperature gradient generated by the electrical stimulation on the water surface, the Marangoni actuators can swim controllably with linear, turning, and rotary motions, mimicking the walking motion of water striders. In addition, the Marangoni actuators can also be driven by light. Importantly, the air-ambient actuators fabricated by SACNT/PI bilayer structures demonstrate the function of grasping objects on the water surface when electrically Joule-heated, mimicking the predation behavior of water striders. With the synergistic effect of the Marangoni actuator and air-ambient actuators, the MSMR can navigate mazes with tunnels and grasp objects. This research will provide a new inspiration for smart actuators and swimming robots.

Conductive Metal-Organic Framework Nanosheets Constructed Hierarchical Water Transport Biological Channel for High-Performance Interfacial Seawater Evaporation.

Solar interfacial water evaporation shows great potential to address the global freshwater scarcity. Water evaporation being inherently energy intensive, Joule-heating assisted solar evaporation for addressing insufficient vapor under natural conditions is an ideal strategy. However, the simultaneous optimization of low evaporation enthalpy, high photothermal conversion, and excellent Joule-heating steam generation within a single material remain a rare achievement. Herein, inspired by the biological channel structures, a large-area film with hierarchical macro/microporous structures is elaborately designed by stacking the nanosheet of a conductive metal-organic framework (MOF), Ni3(HITP)2, on a paper substrate. By combining the above three features in one material, the water evaporation enthalpy reduces from 2455 J g-1 to 1676 J g-1, and the photothermal conversion efficiency increases from 13.75% to 96.25%. Benefiting from the synergistic photothermal and Joule-heating effects, the evaporation rate achieves 2.60 kg m-2 h-1 under one sun plus input electrical power of 4 W, surpassing the thermodynamic limit and marking the highest reported value in MOF-based evaporators. Moreover, Ni3(HITP)2-paper exhibits excellent long-term stability in simulated seawater, where no salt crystallization and evaporation rate degradation are observed. This design strategy for nanosheet films with hierarchical macro/microporous channels provides inspiration for electronics, biological devices, and energy applications.

"Sweat-Driven" MXene Composites with Energy-Storage and Thermal-Management Multifunctions: A Platform for Versatile Electronic Skins.

Most exogenous electronic skins (e-skins) currently face challenges of complex structure and poor compatibility with the human body. Utilizing human secretions (e.g., sweat) to develop e-skins is an effective solution strategy. Here, a new kind of "sweat-driven" e-skin is proposed, which realizes energy-storage and thermal-management multifunctions. Through the layer-by-layer assembly of MXene-carbon nanotube (CNT) composite with paper, lightweight and versatile e-skins based on supercapacitors and actuators are fabricated. Long CNTs wrap and entangle MXene nanosheets, enhancing their long-distance conductivity. Furthermore, the CNT network overcomes the structural collapse of MXene in sweat, improving the energy-storage performance of e-skin. The "sweat-driven" all-in-one supercapacitor with a trilayer structure is patternable, which absorbs sweat as electrolyte and harnesses the ions therein to store energy, exhibiting an areal capacitance of 282.3 mF cm-2 and a high power density (2117.8 µW cm-2 ). The "sweat-driven" actuator with a bilayer structure can be driven by moisture (bending curvature of 0.9 cm-1 ) and sweat for personal thermal management. Therefore, the paper serves as a separator, actuating layer, patternable layer, sweat extractor, and reservoir. The "sweat-driven" MXene-CNT composite provides a platform for versatile e-skins, which achieve the interaction with humans and offer insights into the development of multifunctional wearable electronics.

A PEDOT:PSS/MXene-based actuator with self-powered sensing function by incorporating a photo-thermoelectric generator.

Actuators with sensing functions are becoming increasingly important in the field of soft robotics. However, most of the actuators are lack of self-powered sensing ability, which limits their applications. Here, we report a light-driven actuator with self-powered sensing function, which is designed to incorporate a photo-thermoelectric generator into the actuator based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/MXene composite and polyimide. The actuator shows a large bending curvature of 1.8 cm-1 under near-infrared light (800 mW cm-2) irradiation for 10 s, which is attribute to photothermal expansion mismatch between PEDOT:PSS/MXene composite and polyimide. Simultaneously, the actuator shows enhanced thermoelectric properties with Seebeck coefficient of 35.7 µV K-1, which are mainly attributed to a combination of energy filtering effects between the PEDOT:PSS and MXene interfaces as well as the synergistic effect of its charge carrier migration. The output voltage of the actuator changes in accordance with the bending curvature, so as to achieve the self-powered sensing function and monitor the operating state of the actuator. Moreover, a bionic flower is fabricated, which not only simulates the blooming and closing of the flower, but also perceives the real-time actuation status through the output voltage signal. Finally, a smart Braille system is elaborately designed, which can not only simulate Braille characters for tactile recognition of the blind people, but also automatically output the voltage signal of Braille for self-powered sensing, enabling multi-channel output and conversion of light energy. This research proposes a new idea for exploring multifunctional actuators, integrated devices and self-powered soft robots.

Pencil-Drawn Generator Built-in Actuator for Integrated Self-Powered/Visual Dual-Mode Sensing Functions and Rewritable Display.

Multifunctionality is important to the development of next-generation actuators and intelligent robots. However, current multi-functional actuating systems are achieved based on the integration of diverse functional units with complex design, especially lacking in multi-mode sensing and displaying functions. Herein, a light-driven actuator integrated with self-powered/visual dual-mode sensing functions and rewritable display function is proposed. The actuator demonstrates a bending curvature of 0.93 cm-1 under near-infrared light irradiation. Meanwhile, by embedding a pencil-drawn graphite generator and thermochromic materials, the actuator also provides two independent sensing functions. First, owing to the photo-thermoelectric effect of graphite, the actuator spontaneously outputs a self-powered voltage (Seebeck coefficient: 23 µV K-1 ), which can reflect the deformation trend of actuator. Second, color changes occur on the actuator during deformation, which provide a visual sensing due to the thermochromic property. Furthermore, the actuator can be utilized as a rewritable display, owing to the integrated color-memorizing component. Intelligent robots, switches, and smart homes are further demonstrated as applications. All of them can spontaneously provide self-powered and visual sensing signals to demonstrate the working states of actuating systems, accompanied by rewritable displays on the actuators. This study will open a new direction for self-powered devices, multi-functional actuators, and intelligent robots.

Pressure-Perceptive Actuators for Tactile Soft Robots and Visual Logic Devices.

Soft actuators with sensing capabilities are important in intelligent robots and human-computer interactions. However, present perceptive actuating systems rely on the integration of multiple functional units with complex circuit design. Here, a new-type pressure-perceptive actuator is reported, which integrates functions of sensing, actuating, and decision making at material level without complex combination. The actuator is composed of an actuating unit and a pressure-sensing unit, both of which are fabricated by carbon nanotube (CNT), silk, and polymer composite. On the one hand, the actuating unit can be driven by low voltages (<13 V), owing to a Joule-heating effect. On the other hand, the current passing the pressure-sensing unit can be controlled by tactile pressure. In the integrated actuator, it is able to control the deformation amplitude of actuating unit by applying different pressures on the pressure-sensing unit. A portable tactile-activated gripper is fabricated to operate an object through pressure control, demonstrating its application in tactile soft robots. Finally, three visual logic gates (AND, OR, and NOT) are proposed, which convert "tactile" inputs into "visible" deformation outputs, using the CNT-silk-based material for sensing and actuating in the decision-making process. This study provides a new path for intelligent soft robots and new-generation logic devices.

Chinese ink: a programmable, dual-responsive and self-sensing actuator using a healing-assembling method.

Actuators have wide applications in soft robotics and bionic devices. Since the healing ability not only makes actuators have longer service lives, but also allows them to be programmable through welding and assembling, it is regarded as an important feature for state-of-the-art actuators. Nevertheless, it remains a great challenge to integrate multi-functional merits, such as multi-responsiveness, programmable shape-morphing, healing and self-sensing function, simultaneously into a monolithic actuating material. Here, we introduce Chinese ink, a carbon-based material used in traditional calligraphy, to develop programmable, dual-responsive and self-sensing actuators by a healing-assembling method. The ink is combined with graphene oxide (GO) to fabricate a double-layer ink/GO actuator, which shows bi-directional bending under near-infrared light or humidity, owing to the mismatch of the volume change between ink and GO films. The maximal bending curvature is up to 5.2 cm-1. Importantly, the entire ink/GO actuator can be healed with the aid of ink solution. Using the healing-assembling method to fabricate advanced structures including a Mobius ring, triangular rings and square rings, diverse actuating modes and complex 3D deformations such as a wavy shape and saddle shape are realized. This method also enables the construction of an artificial mimosa that shows a biomimetic stimulus-responsive behavior. In addition, the ink/GO actuator shows a self-sensing function, which is attributed to the thermoresistivity of the ink film. This research shows the huge potential of Chinese-ink-based actuators for use in smart materials, providing a new idea for the development of new generation multi-functional actuators.

A multi-functional light-driven actuator with an integrated temperature-sensing function based on a carbon nanotube composite.

Actuators play an important role in the fields of intelligent robots and wearable electronics. Temperature has a great impact on the performances of many actuators. However, most of the traditional actuators only have an actuating function, failing to monitor and send real-time feedback of the temperature of the actuator. To solve the existing problem and break the single-function limit of traditional actuators, we propose a multi-functional light-driven actuator integrated with a temperature-sensing function, which is based on a carbon nanotube (CNT) and methylcellulose (MC) composite. When the CNT-MC film is assembled with biaxially oriented polypropylene (BOPP) to form a bilayer structure, the CNT-MC/BOPP actuator can be driven by near-infrared (NIR) light. Its morphing is based on thermal expansion differences between two layers and shrinkage of MC induced by water loss. The maximal bending curvature is up to 1.03 cm-1. Meanwhile, the resistance of the actuator can change by about 10%, which realizes real-time temperature monitoring and feedback. Furthermore, we demonstrate two practical applications. First, the CNT-MC film can work as a temperature sensor, as its resistance changes with the temperature in real time. Second, we design an intelligent gripper, which can monitor the temperature during the entire working process. This multi-functional CNT-based device is expected to have a broad application prospect in artificial muscles, soft robotics and wearable electronics.

Programmable and Self-Healing Light-Driven Actuators through Synergetic Use of Water-Shaping and -Welding Methods.

Shape programming is critical for the fabrication of a light-driven actuator with complex shape morphing, which demonstrates potential applications in remote-controlled light-driven soft robots. However, it remains a huge challenge to obtain light-driven actuators having advantages of complex shape morphing, self-healing function, and facile fabrication simultaneously. Here, we report a facile strategy to obtain programmable and self-healing light-driven actuators with complex shape morphing. Various initial shapes of actuators can be programmed by synergetic use of water-shaping and -welding methods, which provides unlimited opportunities for fabricating actuators with predesigned shapes and subsequently demonstrating complex shape morphing. A template transfer method is used to prepare a single-layer graphene oxide (GO) film with asymmetric surface structures, which acts as the basic actuator and has the self-healing function based on the hydrophilic property of GO. It shows bending morphing under near-infrared (NIR) light irradiation due to the photothermal effect and asymmetric morphology on the opposite surfaces. Four more types of actuators are programmed from the basic actuator through the water-shaping method, which exhibits bending, unbending, twisting, and untwisting, respectively, under NIR light illumination. In addition, an S-shape actuator and a flower-shape actuator are programmed from the basic actuators through the water-welding method. By simply turning over the S-shape actuator, it can perform a bidirectional crawling motion. Finally, two intricate bionic light-driven actuators (tendril-shape and octopus-shape) are constructed, which are unattainable from conventional fabrication methods of actuators. We believe that this study will unlock a new way to programmable, self-healing, and light-driven soft robots with tunable and complex shape morphing.

Transparent photoactuators based on localized-surface-plasmon-resonant semiconductor nanocrystals: a platform for camouflage soft robots.

Among the various kinds of actuators, photoactuators with the advantages of wireless and remote manipulation have attracted the interest of many researchers. However, it is challenging to develop transparent photoactuators for camouflage soft robots, because most of the current photoactuators use colored or even black light-absorbing agents. Here, we fabricate a series of transparent actuators by employing localized-surface-plasmon-resonant semiconductor nanocrystals, which mainly respond to infrared light. In this way, we introduce the advantages of wireless and remote manipulation into the camouflage soft robots. Three semiconductor nanocrystals (In2O3:Sn, W18O49 and CuS nanocrystals) are fabricated as the photothermal conversion agents to construct the photoactuators. Owing to the weak absorption of visible light, the fabricated actuators exhibit high transparency (maximum transmittance >72% at 600 nm). Meanwhile, they demonstrate remarkable deformations upon near infrared light irradiation (bending curvature up to 0.66 cm-1). Finally, a worm-like crawling robot, a glasswing butterfly robot and a two-finger robot hand are constructed to demonstrate the ability of remote manipulation and inconspicuousness in both the robot appearance and the driving signal, attaining excellent passive camouflage function. These results provide a promising platform for remote-controlled camouflage soft robots and biomimic applications, which will be of significance in the field of soft robotics.

Transparent actuator made by highly-oriented carbon nanotube film for bio-inspired optical systems.

Transparent actuators can be used in variable-focus lens, tactical displays and so on. However, previous transparent actuators made with dielectric elastomer mostly required high driving voltages (>1000 V) for actuation. In this work, we propose a new kind of low-voltage-driven transparent actuator, which is made with polymer and single-layer highly-oriented carbon nanotube (HOCNT) film composites, fully utilizing the favorable conductivity and high transparency of HOCNT film. The HOCNT-based transparent actuator shows a transmittance as high as 70%. When applying a voltage of 100 V, the transparent actuator bends visibly with a displacement of 14 mm. The actuation mechanism is a large volume change between polymers when they are Joule-heated by the electrical current. In addition, a solid-state lens based on the transparent actuator is fabricated, which demonstrates an obvious magnification effect with electrical-driven actuation. Finally, a bio-inspired optical system based on the solid-state lens is also constructed, which can mimic the focusing behavior of the human eyeball. The transparent actuator proposed in this work would have potential applications in optical devices, artificial muscles and soft robotics.

Long-Lasting and Easy-to-Use Rewritable Paper Fabricated by Printing Technology.

Nowadays, urged by the high demand to reduce paper consumption, rewritable paper receives more and more attention. However, it is a great challenge to conveniently fabricate the rewritable paper which has long legible time of information and is easy to use simultaneously. Here, we report a new type of long-lasting rewritable paper based on color-memorizing thermochromic dye and photothermal-converting toner, which is fabricated by a two-step printing process. The rewritable paper demonstrates excellent rewriting performances (legible time > 6 months and reversibility > 100 times). The thermochromic effect is based on a temperature-driven phase change mechanism, accompanied by a lactone ring tautomerism of crystal violet lactone. The color of the rewritable paper rapidly changes from blue to colorlessness when the temperature is higher than 65 °C, and the colorless state can be maintained at room temperature. The color returns to blue when the temperature is lower than -10 °C. By using an electrothermal pen, a thermal printer, and near infrared (NIR) light, characters and images with high resolution can be handwritten, thermal-printed, and photoprinted on the rewritable paper. The written/printed information can be cleaned under lower temperature or can be quickly erased by NIR light. This rewritable paper is easy for large-scale production and will have promising opportunities in practical applications, such as long-lasting information recording and reading, rewritable label, reprintable displays, and so on.

Humidity- and light-driven actuators based on carbon nanotube-coated paper and polymer composite.

Multi-responsive actuators driven by different stimuli (e.g. light, humidity, electricity) have attracted intense attention recently for the advantages of being used in various environments and show enormous actuation. In this work, we propose humidity- and light-driven actuators based on carbon nanotube (CNT)-coated paper and a biaxially oriented polypropylene (BOPP) composite. The CNT-paper/BOPP actuator shows large bending actuation when driven by humidity change (curvature of 1.2 cm-1) and near infrared (NIR) light irradiation (curvature up to 1.6 cm-1). The great actuation performances outperform most other paper-based actuators. Finally, a smart gripper, of which the initial opening width can be enlarged, is fabricated on the basis of the CNT-paper/BOPP actuators. By utilizing the bidirectional bending motion of the actuator, the opening width of the gripper can increase to a width that is 4 times larger than its initial width, so as to grasp a large object. The gripper is also able to raise and move an object that is 20 times heavier than one actuator of the gripper. We assume that this new type of actuator has great potential in artificial muscle, soft robotics and biomimetic applications.

Multi-responsive actuators based on a graphene oxide composite: intelligent robot and bioinspired applications.

Carbon-based electrothermal or photothermal actuators have attracted intense attention recently. They can directly convert electrical or light energy into thermal energy and exhibit obvious deformations. However, if the actuation mechanism is only limited to thermal expansion, the deformation amplitude is difficult to increase further. Moreover, complex shape-deformation is still challenging. Although a few materials were reported to realize twisting or untwisting actuation by cutting the samples into strips along different orientations, each single strip could perform only one shape-deformation mode. In this work, we propose multi-responsive actuators based on a graphene oxide (GO) and biaxially oriented polypropylene (BOPP) composite, which are designed with different shapes (strip-shape and helical-shape). The strip-shape GO/BOPP actuator shows great bending actuations when driven by humidity (curvature of up to 3.1 cm-1). Due to a developed dual-mode actuation mechanism, the actuator shows a bending curvature of 2.8 cm-1 when driven by near infrared (NIR) light. The great actuation outperforms most other carbon-based actuators. Then, an intelligent robot based on the GO/BOPP composite is fabricated, which can switch between the protection mode and weightlifting mode with different external stimuli. Inspired from plant tendrils, a bioinspired helical GO/BOPP actuator is further realized to show both twisting and untwisting actuations in a single actuator, fully mimicking the deformation of plant tendrils. Finally, a robot arm consisting of strip-shape and helical GO/BOPP actuators can grasp an object that is 2.9 times heavier than itself, demonstrating promising bioinspired applications.

Transparent actuators and robots based on single-layer superaligned carbon nanotube sheet and polymer composites.

Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to fabricate a high-performance transparent actuator based on single-layer superaligned carbon nanotube sheet and polymer composites. Various advantages of single-layer nanotube sheets including high transparency, considerable conductivity, and ultra-thin dimensions together with selected polymer materials completely realize all the above required advantages. Also, this is the first time that a single-layer nanotube sheet has been used to fabricate actuators with high transparency, avoiding the structural damage to the single-layer nanotube sheet. The transparent actuator shows a transmittance of 72% at the wavelength of 550 nm and bends remarkably with a curvature of 0.41 cm(-1) under a DC voltage for 5 s, demonstrating a significant advance in technological performances compared to previous conventional actuators. To illustrate their great potential usage, a transparent wiper and a humanoid robot "hand" were elaborately designed and fabricated, which initiate a new direction in the development of high-performance invisible robotics and other intelligent applications with transparency.

A large-deformation phase transition electrothermal actuator based on carbon nanotube-elastomer composites.

An electrothermal phase transition actuator based on a superaligned carbon nanotube film and elastomers has been designed and fabricated. Compared with a conventional electrothermal bimorph actuator using cantilever structures, this new-type actuator introduces a novel concept of phase transition large-deformation actuation. The actuator consists of an enclosed cavity made up of highly elastic elastomers and an embedded carbon nanotube based electrical heater. A low-boiling liquid was injected into the cavity and it can vaporize rapidly to make the elastic cavity expand significantly when electrically heated. The size and speed of the expansion can be easily controlled by the applied voltage (electrical power). The expanded elastomer membrane can lift more than 1000 times of its own weight. The cyclic actuation test shows the excellent durability of the actuator. A heart-shaped closed liquid circulation system based on the phase transition pump-type actuators has been made, which can work like a real heart. Owing to the advantages of low driving voltage, large deformation, simple fabrication, easy operation, lightweight and durability, we think that the phase transition actuator will have great potential usage in various areas, such as artificial muscles, soft robots, sensors, and especially in the biomedical field.

Large-Deformation Curling Actuators Based on Carbon Nanotube Composite: Advanced-Structure Design and Biomimetic Application.

In recent years, electroactive polymers have been developed as actuator materials. As an important branch of electroactive polymers, electrothermal actuators (ETAs) demonstrate potential applications in the fields of artificial muscles, biomimetic devices, robotics, and so on. Large-shape deformation, low-voltage-driven actuation, and ultrafast fabrication are critical to the development of ETA. However, a simultaneous optimization of all of these advantages has not been realized yet. Practical biomimetic applications are also rare. In this work, we introduce an ultrafast approach to fabricate a curling actuator based on a newly designed carbon nanotube and polymer composite, which completely realizes all of the above required advantages. The actuator shows an ultralarge curling actuation with a curvature greater than 1.0 cm(-1) and bending angle larger than 360°, even curling into a tubular structure. The driving voltage is down to a low voltage of 5 V. The remarkable actuation is attributed not only to the mismatch in the coefficients of thermal expansion but also to the mechanical property changes of materials during temperature change. We also construct an S-shape actuator to show the possibility of building advanced-structure actuators. A weightlifting walking robot is further designed that exhibits a fast-moving motion while lifting a sample heavier than itself, demonstrating promising biomimetic applications.

High-performance, low-voltage, and easy-operable bending actuator based on aligned carbon nanotube/polymer composites.

In this work, we show that embedding super-aligned carbon nanotube sheets into a polymer matrix (polydimethylsiloxane) can remarkably reduce the coefficient of thermal expansion of the polymer matrix by two orders of magnitude. Based on this unique phenomenon, we fabricated a new kind of bending actuator through a two-step method. The actuator is easily operable and can generate an exceptionally large bending actuation with controllable motion at very low driving DC voltages (<700 V/m). Furthermore, the actuator can be operated without electrolytes in the air, which is superior to conventional carbon nanotube actuators. Proposed electrothermal mechanism was discussed and confirmed by our experimental results. The exceptional bending actuation performance together with easy fabrication, low-voltage, and controllable motion demonstrates the potential ability of using this kind of actuator in various applicable areas, such as artificial muscles, microrobotics, microsensors, microtransducers, micromanipulation, microcantilever for medical applications, and so on.

Highly flexible and all-solid-state paperlike polymer supercapacitors.

In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 µA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

A Demo opto-electronic power source based on single-walled carbon nanotube sheets.

It is known that single-walled carbon nanotubes (SWNTs) strongly absorb light, especially in the near-infrared (NIR) region, and convert it into heat. In fact, SWNTs also have considerable ability to convert heat into electricity. In this work, we show that SWNT sheets made from as-grown SWNT arrays display a large positive thermoelectric coefficient (p-type). We designed a simple SWNT device to convert illuminating NIR light directly into a notable voltage output, which was verified by experimental tests. Furthermore, by a simple functionalization step, the p- to n-type transition was conveniently achieved for the SWNT sheets. By integrating p- and n-type elements in series, we constructed a novel NIR opto-electronic power source, which outputs a large voltage that sums over the output of every single element. Additionally, the output of the demo device has shown a good linear relationship with NIR light power density, favorable for IR sensors.