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Indium tin oxide (ITO) is widely used as a substrate for fabricating chips because of its optical transparency, favorable chemical stability, and high electrical conductivity. However, the wettability of ITO surface is neutral (the contact angle was approximately 90&deg, ) or hydrophilic. For reagent transporting and manipulation in biochip application, the surface wettability of ITO-based chips was modified to the hydrophobic or nearly hydrophobic surface to enable their use with droplets. Due to the above demand, this study used a 355-nm ultraviolet laser to fabricate a comb microstructure on ITO glass to modify the surface wettability characteristics. All of the fabrication patterns with various line width and pitch, depth, and surface roughness were employed. Subsequently, the contact angle (CA) of droplets on the ITO glass was analyzed to examine wettability and electrical performance by using the different voltages applied to the electrode. The proposed approach can succeed in the fabrication of a biochip with suitable comb-microstructure by using the optimal operating voltage and time functions for the catch droplets on ITO glass for precision medicine application. The experiment results indicated that the CA of droplets under a volume of 20 &mu, L on flat ITO substrate was approximately 92&deg, &plusmn, 2&deg, furthermore, due to its lowest surface roughness, the pattern line width and pitch of 110 &mu, m exhibited a smaller CA variation and more favorable spherical droplet morphology, with a side and front view CA of 83&deg, 1&deg, and 78.5&deg, 2.5&deg, respectively, while a laser scanning speed of 750 mm/s was employed. Other line width and pitch, as well as scanning speed parameters, increased the surface roughness and resulted in the surface becoming hydrophilic. In addition, to prevent droplet morphology collapse, the droplet&rsquo, s electric operation voltage and driving time did not exceed 5 V and 20 s, respectively. With this method, the surface modification process can be employed to control the droplet&rsquo, s CA by adjusting the line width and pitch and the laser scanning speed, especially in the neutral or nearly hydrophobic surface for droplet transporting. This enables the production of a microfluidic chip with a surface that is both light transmittance and has favorable electrical conductivity. In addition, the shape of the microfluidic chip can be directly designed and fabricated using a laser direct writing system on ITO glass, obviating the use of a mask and complicated production processes in biosensing and biomanipulation applications.

A 43-μm-thick Si(111) substrate was obtained using the stress-induced lift-off method with a screen-printed metal paste layer as the stress-generation layer. The reflection of the metal-removed side of the Si(111) substrate was lower than that of the exfoliated side because of high surface roughness resulting from the reaction between the metal paste and the silicon substrate at 700◦C. After aggressive etching with an alkaline solution for the peeled silicon substrate, the efficiency of the heterojunction silicon solar cell was improved from 0.87% to 12%. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0171508jss] All rights reserved.

This study proposes a promising silicon (Si) solar cell structure for reducing the potential induced degradation (PID) of crystalline Si solar cells. Phosphorous silicate glass (PSG) layers were carefully designed on an emitter layer, and the thickness of these layers (dPSG) was controlled by adjusting the diffusion temperature and time. The results show that the power loss remarkably decreased from 31% (dPSG = 0 nm) to 11% (dPSG = 22.3 nm) and further decreased to less than 5% after a 48-h PID test when dPSG was higher than 23.3 nm. No additional process or equipment was required for producing this effective and low-cost solar cell. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any

A 3 μm thick silicon layers with nano-scale honeycomb structure on the surface were fabricated using the mask-less process, “Thermal-stress Induced Pattern Transfer method”. The thin silicon layer was deposited on a patterned sapphire substrate with nano-scale pyramids, followed by a metal layer printing on the top of the thin silicon layer. After thermal treatment, a thin silicon layer was peeled off from the patterned sapphire substrate and was transferred to the metal layer. Meanwhile, the periodic patterns on the sapphire substrate were transferred to the thin silicon layer forming the honeycomb structure on the surface of the silicon layer. The whole process was operated at a low temperature below 250 °C without any mask process. Finally, the solar cell was fabricated on the silicon thin layer and its performance was measured. The short circuit current density is 0.11 mA/cm2.

This letter presents a wafer-level approach for producing rollable single-crystal silicon integrated circuit (IC) wafers, bent with a 17-mm minimum radius of curvature, achieved by backside nanotexturing. The three-point bending test indicates a mechanical strength enhancement by a factor of 2.3 for nanotextured 60- $\mu \text{m}$ thick samples. The minimum radius of curvature decreased by 43.4%, exhibiting improved flexibility. The carrier charge mobility increases by 4.9%, 12.6%, and 16.9% for the bending radii of 45, 30, and 24 mm, respectively. The increment of the mobility corresponds with the changing compressive stress in p-MOSFETs fabricated on the IC wafer.

Photovoltaic, microelectromechanical systems, and integrated circuit industries are demanding a technology to enable the high rupture resistant silicon wafer production to improve the manufacturing yield. The presented silicon nanotexture patterning on the edges and sidewalls by wet chemical etching process can protect single-crystalline and multicrystalline silicon samples from rupture. Bending tests indicate a mechanical strength enhancement of ~ 72%-75% for sc-silicon and ~71%-73% for mc-silicon samples. In addition, the front and back surfaces of the samples remain intact and appropriate for any further semiconductor processes. This technology was implemented in solar cells that exhibited a strength improvement of nearly 73% without affecting their photovoltaic performances, anticipating an effective solution for the solar cell manufacturing industry.

Backside nanotexturing fabricated by electroless metal assisted wet chemical etching, protected with a deposited thin silicon layer, is a new approach to create high bending strength silicon samples. Bending strength for protected nanotextured samples followed by CMP process was enhanced by ∼3.4 folds as compared to polished silicon samples, which emphasize the possibility of industrial implementation. The morphology of silicon deposition layer upon nanotexture influences the stress behavior, which need an adequate fabrication technique for uniform deposition at wafer scale. The thin protection layer upon nanotexture prevents the unwanted particle trapping, which affects the electrical performances of the device. Moreover, this technology provides a rupture resistive solution for IC, MEMS and photovoltaic devices for industrial implementation.

The nanopatterned c -plane sapphire substrate with different morphologies can be successfully used to grow polar and nonpolar GaN epilayers. The nanopattern of sapphire substrate was prepared with natural lithography and dry-etching methods and the following GaN epilayer was grown by MOCVD. The GaN crystal orientation and crystalline quality were then characterized by high resolution X-ray diffraction, which reveals the GaN epilayer can be c -plane (0001) or m -plane (1010) orientation depending on the surface morphology of nanopatterned sapphire substrate. The corresponding full width at half maximum of the rocking curves for c - and m -plane GaN are 211 and 316 arcsec, respectively. The rms surface roughness was measured to be 0.3 nm by atomic force microscopy. The atomic structure of the sapphire-GaN heterointerface was studied by high resolution transmission electron microscope to reveal the growth mechanism. Furthermore, photoluminescence, time-resolved photoluminescence, and polarization Raman spectroscopy were employed to realize the optical and structural properties of these GaN epilayers.

An Ultrathin (~10 nm) InN ion sensitive field effect transistor (ISFET) with gate regions functionalized with phosphotyrosine (p-Tyr) is proposed to detect calcium ions (Ca2+) in aqueous solution. The ISFET was miniaturized to a chip size of 1.1 mm by 1.5 mm and integrated at the tip of a hypodermic injection needle (18 G) for real-time and continuous monitoring. The sensor shows a current variation ratio of 1.11% with per decade change of Ca2+ and a detection limit of 10-6 M. The response time of 5 sec. reveals its great potential for accomplishing fast detection in chemical and physiological sensing applications. The sensor would be applied in medical diagnosis and used to monitor continuous and real-time variations of Ca2+ levels in human blood in the near future.

Nonpolar ( 10 1 ¯ 0 ) m-plane GaN epilayer was grown on nanoscale patterned c-plane sapphire substrates by MOCVD. The nanoscale patterned sapphire substrates were fabricated by natural lithography and dry etching methods. The nanopatterns are defined particularly with no c-plane surfaces exposed. The ( 10 1 ¯ 0 ) m-plane GaN epilayer was characterized by X-ray diffraction and atomic force microscope, which indicated the FWHM of the rocking curve is 316 arcsec and the rms surface roughness is 0.3 nm, respectively. The SEM and TEM studies reveal that the m-plane GaN grains nucleate on the exposed n-plane facets of the etched c-plane sapphire substrates.

The wafer-level aperiodic nanostructures were fabricated atop the sapphire substrates in order to increase the transmittance over broadband spectra. The fabrication was presented along with characterization of their optical properties. The nanostructures were patterned using natural lithography with nickel silicide as a hard mask, and the subsequent etching was performed using inductively coupled plasma dry-etching method. The sapphire substrates with nanostructures compared to conventional sapphire substrates, which exhibit antireflective characteristics over broadband spectra at a wide range of incident angles. The nanostructures reduce the reflection down to 5% in the visible spectrum for normal incidence. The transmittance of visible to near-IR spectra was found to be 94% at normal incidence and over 90% at an incident angle of 45°. In the mid-IR spectrum, the transmittance exceeds 88% until the reflection is no longer suppressed by nanostructures. The polarization properties have also been investigated. The nanostructures can enhance the reflectivity ratio 90% for wavelengths shorter than 400 nm. As the amplitude ratio, enhanced from 50% to 80% over the whole visible spectrum.

The purpose of this research is to develop a self-alignment mechanism using surface tension and solid edge for tiny microchips package. The solid edge of a rectangular protrusion replaced the surface treatment, which is usually used in the self-alignment technology. The experiments result showed that the commercial Radio Frequency Identification (RFID) microchip could be accurately auto-aligned on the protrusion. The edge effect, which confined the droplet spreading, is stronger than the boundary of hydrophilic and hydrophobic surface generated by the surface treatment. The standard deviation of aligned position was smaller than 16 μm when the surface area of water droplet on protrusion was near to the bottom area of RFID microchip. The self-alignment completed in a tenth of a second. There was no visible position shift on aligned RFID microchip after suffering the simulated motion of transportation. The self-alignment mechanism in this paper can begin a new era of an innovative microchip package process without extra requirement on the microchips.

This paper presents an elliptical dielectric liquid lens for presbyopia glasses. This lens provides the tunable diopter from 0.9 D to 2.6 D by adjusting the voltage of dielectric liquid lens. The liquid lens's horizontal and vertical filed of view (FOV) are 26° and 20°. The diopter adjusting time is around 1 sec.

A tunable liquid-crystal microlens with hybrid alignment was fabricated using micro-imprinting technology. The imprinted hybrid alignment, which was surrounded by homogeneous (homeotropic) alignment, resulted in spatial refractive-index distribution of liquid-crystal molecules in the microlens. With different hybrid-alignment configurations, the microlens functioned either as a convex or concave lens. The focal length of the microlens was electrically controlled at applied voltages of less than 4 V. The focal length was adjusted from 7.8 to 8.6 mm and from −10 to −35 mm for a convex and a concave lens, respectively. The rising response time was 0.5 s, and the falling response time was 5 s.

The electric breakdown of gaseous dielectrics predicted by Paschen's law has been successfully employed for the design of insulation among metallic conductors separated by millimeter scale gaps or larger. However, today most electrostatic actuated MEMS devices have been designed and fabricated with micron-scale gaps that lead to a high risk of failure. Paschen's curves measured under macro or meso gaps hereby must be re-examined and carefully evaluated for providing the guidelines of insulation design in MEMS devices. In this paper, geometric configurations commonly employed for MEMS electrodes, typically planar and inter-digitated combs, have been designed and analyzed with commercial software packages. For verification purposes, breakdown voltages were measured on test samples fabricated with metallic, p-type and n-type silicon substrates in standard MEMS processes. The samples were prepared by etching insulation gaps measured from 2 to 21 µm. In conclusion, Paschen's curves for describing the electric breakdown phenomena of gaseous dielectrics were revisited and compared to the published data so that design guidelines of electrical insulation in MEMS actuators are established.

The controllability of cell manipulation using image dielectrophoresis (DEP) was characterized regarding DEP affinity test of cells, effective DEP radius, threshold voltage and parallel manipulation. The reconfigurable electrodes for DEP were achieved using an optically addressable projection array of 800 by 600. Each optical pixels projected on the chips were measured to be 25 μm by 25 μm. Individual pixels were controlled through a computer using a mouse cursor or pre-programmed flashes as projection patterns over a period of time. Based on the result of the DEP affinity test, effective DEP radius and threshold voltages, the parallel manipulation of cells without interfering each other was demonstrated.

This paper presents the development of a portable microscope with dielectric liquid lens. This device provides the tunable working distance from 7.6 mm to 6.7 mm by adjusting the voltage of dielectric liquid lens. The liquid lens's response time is about 200 ms and electric power consumption about 0.32 mW.

This paper presents a novel sensing array with tunable sensing ranges for dynamic tactile sensing. Each element in the array contains a droplet with variable shape. By controlling the dielectric force applying on the droplet, the shape of the droplet can be controlled. The sensing range was tuned due to the variation of the droplet shape. This sensing array can be not only used in static tactile sensing but also in dynamic tactile sensing. The experiment result shows the sensing range, from 0.6 N to 1.05 N, can be tuned in 100 ms.

This paper presents a novel tactile sensing array with adjustable sensing ranges. Each sensing element contains a low dielectric constant (er) droplet covered with high er liquid. We controlled the contact angle of the droplet by controlling the electric flux passing through the element. Then, the sensing ranges and sensitivity were also adjusted due to the variation of the droplet shape. The results show the sensor's sensing range is easily adjusted from 0.33N ~ 1.05N to 0.04N ~ 0.60N. And the sensitivity is also adjusted from 1.47pF/N to 2.90.pF/N.

This work presents silicon flapping wings design with higher bending strength and low reflectivity for MEMS aircraft. The design was bio-inspired by the cicada wings which are having numerous nanostructures upon it. The nanostructure on silicon increases the bending strength by ~6 times. The higher strength silicon samples can successfully demonstrate the 100 μm thick bendable silicon by nanostructure surface texturing used for flapping wings. Moreover, same nanostructures act as antireflective layer due to improved light trapping for solar cell. The reflectivity of the nanotextured surface reduces to ~2%.

This paper presents a novel capacitive tactile sensor with high sensitivity for humanoid robots. The main structure of the sensor is a cubic ‘box’ (3 × 3 × 2.5 mm3) made of Polydimethylsiloxane (PDMS). Two dielectric liquids, i.e. a polyalcohol droplet (with a higher dielectric constant) surrounded by oil (with a lower dielectric constant), were sealed in the box under iso-density condition. Electrodes were fabricated on the upper and lower inner surfaces of the box to form a capacitor. The two liquids, sandwiched by the electrodes, increased the capacitance of the capacitor. The sensitivity of the sensor increased due to the novel configuration. The proposed sensor was fabricated by microfabrication technology. This sensor's sensitivity is 61.77%/N, which is 3.3 times greater than that of typical sensors containing no liquid.

Multicrystalline silicon (mc-Si) photovoltaic (PV) solar cells with nanoscale surface texturing by metal-nanoparticle-assisted etching are proposed to achieve high power efficiency. The investigation of average nanorod lengths from 100 nm to 1 μm reveals that the Si wafer decorated with 100 nm thick nanorods has optical reflection of 9.5% inferior than the one with 1 μm thick nanorods (2%). However, the short nanorods improve the doping uniformity and effectively decrease metal contact resistance. After surface passivation using the hydrogenated SiO[subscript 2]/SiN[subscript x] (5 nm/50 nm) stack, the minority carrier lifetime substantially increases from 1.8 to 7.2 μs for the 100 nm-thick nanorod solar cell to achieve the high power efficiency of 16.38%, compared with 1 μm thick nanorod solar cell with 11.87%., National Science Council of Taiwan (project 100-2120-M-007-011-CC2)

A new morphology of nanopatterned sapphire substrates (NPSS) was presented, which applied in LEDs exhibited an output power of 33.1 mW, higher than that on flat substrates 2.4-fold, owing to void-embedded NPSS with cortexlike nanostructures.

This paper presents wafer-level aperiodic nanostructures fabrication of sapphire substrates with broadband optical transmittance. The nanostructures were patterned by using nickel silicide as a hard mask, and performed by inductively coupled plasma reactive ion etching. The sapphire substrates with nanostructures exhibit high transmittance at wide incident angles over broadband spectra compared with conventional sapphire substrates. The transmittance of visible to near-IR spectra was found to be 94%. In the mid-IR spectrum, the transmittance exceeds 88% until the reflection is no longer suppressed by nanostructures. The polarization properties show the nanostructure enhances the reflectivity ratio by at least 50%.

Two smart optical components, which composed of two immiscible dielectric liquids, were introduced in this article. The liquid-liquid interface manipulation by dielectric force was applied to achieve the adaptive optical function, including variable focal length and variable aperture. The maximum optical power change of the experimental dielectric liquid lens was up to 91 diopter (D) while the actuation voltage was turned to 41 V rms . Meanwhile, its maximum power consumption lowered than 0.4 mW. A variable focus dielectric liquid lens enables to change the effective focus length of a lens module. That can be used in the application of auto-focusing or zoom. A 2 megapixel compact camera module integrated with a dielectric liquid lens showed its ability to focus at variable distance. Its minimal focus distance achieves to be 1cm. A dielectric liquid iris was demonstrated its ability to control the amount of passing light. The aperture turning ratio was up to 65% and the transparent of its opening area was up to 85%.

A cell rotation method by using optoelectronic tweezers (OET) is reported. The binary image of a typical OET device, whose light and dark sides act as two sets of parallel plates with different ac voltages, was used to create a rotating electric field. Its feasibility for application to electrorotation of cells was demonstrated by rotating Ramos and yeast cells in their pitch axes. The electrorotation by using OET devices is dependent on the medium and cells’ electrical properties, the cells’ positions, and the OET device’s geometrical dimension, as well as the frequency of the electric field.

A dynamic response of liquid microlens using dielectric force was demonstrated using comparison between experimental and simulation results. The theoretical results of the simulation match fairly well with the experiment in liquid microlens with a diameter of 500 μm. An high speed motion camera with a speed of 3000 fps was used to capture the images of dynamic response for 500μm, 2mm and 5mm droplets in diameter, respectively. Results indicate that a viscosity strongly affects dynamic response time for 2mm droplet in diameter, but only weakly impacts on final contact angle. A propagation of wave on the droplet surface was found when 100V rms voltage applied on microlens with a diameter of 5mm. The study may provide the basis for development of optical liquid microlens.

A method for the reduction of defect density in GaN epilayer using nanoscale patterned sapphire substrates (NPSS) was proposed. The sapphire substrates were patterned by natural lithography and inductively coupled plasma reactive ion etching (ICP-RIE). The undoped GaN films were grown on NPSS through metal organic chemical vapor deposition. The pits density was analyzed by atomic force microscope (AFM) and threading dislocation distribution was observed by scanning electron microscopy (SEM). The optical characteristics were measured from X-ray diffractometry and photoluminescence spectroscopy. These results indicate NPSS can improve crystalline quality by effectively reducing threading dislocations.

We demonstrate a liquid iris diaphragm using dielectric force, enabling its aperture to vary from 4 mm at the resting state to 1.5 mm at 160 V(rms). The liquid iris is a packaged optical component comprised of transparent oil, opaque ink, and a set of driving electrodes on a glass substrate. The iris aperture shrinks with the dielectric force, which is exerted on the interface between the two nonconductive liquids. The transmittance was measured to exceed 85% with no antireflection coatings over the spectrum of visible light. The maximum electric power consumed is measured to be 5.7 mW.

Microlens arrays were self-assembled from microballs using dielectrophoretic energy wells. Energy wells defined by patterned dielectric were used to produce microlens arrays with array patterns of desire. Microballs of 25microm in diameter were measured to have numerical aperture of 0.8 and focal length of 15.5microm. The optical resolution was found to be 0.4microm. Both the numerical aperture and the focal length were further adjusted to 0.66 and 19.0microm by a post-assembly heat treatment at 190 degrees C for 5 minutes.

Ion selective electrodes (ISEs) and ion selective field effect transistors (ISFETs) based on indium nitride (InN) film were used for detecting anions in aqueous solutions. The positively charged surface states on InN surfaces selectively adsorbed anions, building Helmholtz voltages near the InN/solution interface was confirmed using open-circuit potentiometric and I–V measurements. The InN-based ISE obeyed the Nernst equation with the sensitivity of 45 and 49 mV/decade for chloride and hydroxyl ions, showing remarkable selectivity, response time, stability and repeatability. Ultrathin (~10 nm) InN ISFETs demonstrated ion sensing with a sensitivity of 5 μA per decade and a response time less than 10s. Molecular-beam epitaxy (MBE) system was used to conduct the epitaxial growth of InN film on Si (111) substrate, enabling the InN based chemical sensors to integrate with the wireless sensors on the same chip to transmit real-time sensing data.

By way of hydrophobic coating on the exterior and interior surface of silicon photonic crystal, color of silicon photonic crystal can be changed with a sub-second response time via liquid infiltration and exfiltration.

Dual-photoresist complementary lithography technique consisting of inorganic oxide photoresist and organic photoresist is applied to produce the submicron pit array patterns on a sapphire surface. The oxide photoresist is patterned by direct laser writing, and the developed pit size decreases to a smaller value than the laser spot size due to the thermal lithography. The oxide photoresist possesses strong etching resistance against oxygen plasma but shows no resistance against chlorine plasma. During the ion-coupled-plasma reactive-ion-etching process, chlorine plasma is a necessary component to etch the sapphire. Moreover, the characteristics of organic resist are opposite those of oxide photoresist and possess moderate resistance against chlorine plasma but no resistance against oxygen plasma. The thermal and developing characteristics of oxide photoresist are reported in this study. The dependence of laser power on the developed mark sizes and morphologies is examined by atomic force microscopy. The temperature distribution on the photoresist structure during the laser writing is simulated, and the thermal lithography concept is introduced to explain the effect of power on the developed oxide mark width. Images of patterned pit array on a commercial 4-inch-diameter sapphire substrate are also shown.

The silicon-based heterostructures composed of silicon nanowire/silver oxide/silver nanodendrite are first demonstrated as functional light emitting sources after electro-activation. The high fill-factor nanoscale out-of-plane heterostructures are fabricated into silicon substrate using low-cost silver nanoparticles assisted wet chemical etching. The emitted light spectrum spanning a visible–NIR range of 400-850 nm is analyzed to excite three predominant intensity peaks with photon energies of 1.87, 2.05 and 2.27 eV under forward biases of 20-50 V, corresponding to the color of dark red, yellow and green. The heterostructure device proposed paves a way to eliminate the use of relatively expensive direct band gap materials for the potential optoelectronic applications, such as optical interconnections and displays.

High-efficiency GaN-based light-emitting diodes (LEDs) with an emitting wavelength of 438 nm were demonstrated utilizing nanoscale patterned sapphire substrates with void-embedded cortex-like nanostructures (NPSS-VECN). Unlike the previous nanopatterned sapphire substrates, the presented substrate has a new morphology that can not only improve the crystalline quality of GaN epilayers but also generate a void-embedded nanostructural layer to enhance light extraction. Under a driving current of 20 mA, the external quantum efficiency of an LED with NPSS-VECN is enhanced by 2.4-fold compared with that of the conventional LED. Moreover, the output powers of two devices respectively are 33.1 and 13.9 mW.

This study discusses sacrificial bridges that are used to release MEMS devices. Before being released, sacrificial bridges connect all the component structures into an integral structure. Solder bump bonding is used to mount the MEMS chip on another chip or a printed circuit board (PCB) and to maintain the alignment among all component structures after removal of the sacrificial bridges. Two types of sacrificial bridges were designed, analyzed and fabricated. The fabrication process?which used low resistivity single crystal silicon (SCS) wafers as the device material?was developed to implement the sacrificial bridges. Novel SCS through silicon vias (TSVs), which interconnect stacked chips, was made using the same process. An electrostatic comb drive actuator was fabricated and mounted onto a PCB. The fabricated actuator was tested to demonstrate the feasibility of the fabrication process, sacrificial bridges and SCS TSVs. The results show that the actuator worked well. Its maximum displacement and resonant frequency were 69.9 ?m and 406 Hz, respectively. This method is promising for the delivery of a novel 3D system in package for MEMS devices.

This study demonstrated a tunable photonic crystal (PhC) with 70 nm-wide spectral tuning (535 nm to 605 nm) and 3 ms of response time. The tunable PhC is based on reciprocal capillary action of liquid in the nanoscale PhC voids. By wetting the porous silicon PhC with ethanol and water, the PhC can be bistably switched respectively between liquid-filled state (orange color) and vapor-filled state (yellow color). Owing to the energy barrier between the two wetting states, the tunable PhC can remain at either of the two states with no external power consumption.

A 25-pixel illumination system composed of a 5 × 5 dielectric liquid-lens (DLL) zoom module array, 25 light-emission diodes (LEDs), and a secondary optical lens demonstrates 3D light field manipulation. LEDs function as 2D illumination pixels while the DLL module array performs longitudinal illuminance adjustability by zooming each illumination pixel. A test on the similarity of two illuminance patterns between experiments and simulations shows a normalized cross correlation (NCC) higher than 0.8, indicating the feasibility of the system design. Also, the illumination system is further applied to correct a distorted light pattern on a 45° tilt screen as well as to perform light compensation on distance-differential objects.

A tunable photonic crystal (PhC) based on the capillary action of liquid is demonstrated in this work. The porous silicon-based photonic crystal (PSiPhC) features periodic porosity and is fabricated by electrochemical etching on 6" silicon wafer followed by hydrophobic modification on the silicon surface. The capillary action is achieved by varying the mixture ratio of liquids with high and low surface tension, yielding either capillary attraction or capillary repulsion in the nanoscale voids of the PSiPhC. By delivering the liquid mixture into and out of the voids of the PSiPhC, the reflective color of the PSiPhC can be dynamically tuned.

Ultrathin (∼10nm) InN ion selective field effect transistors (ISFETs) have been demonstrated to perform ion sensing in aqueous solutions with a sensitivity of 5μA/decade and a response time smaller than 10s. The positively charged surface states on InN surfaces selectively adsorb anions, building Helmholtz voltages in solutions and modulating the drain-source current of the ISFETs. The ISFET performance is greatly enhanced by depleting carriers in the ultrathin InN channel where the film thickness is close to depth of surface electron accumulation.