Subwavelength hole arrays with nanoapertures fabricated by scanning probe nanolithography

Owing to their surface plasmon-based operation, arrays of subwavelength holes show extraordinary electromagnetic transmission and intense field localizations of several orders of magnitude. Thus they were proposed as the basic building blocks for a number of applications utilizing the enhancement of nonlinear optical effects. We designed and simulated nanometer-sized subwavelength holes using an analytical approach. In our experiments we used the scanning probe method for nanolithographic fabrication of subwavelength hole arrays in silver layers sputtered on a positive photoresist substrate. We fabricated ordered nanohole patterns with different shapes, dispositions and proportions. The smallest width was about 60 nm. We characterized the fabricated samples by atomic force microscopy

Surface plasmon - Polariton assisted metal-dielectric multilayers as passband filters for ultraviolet range

We designed and fabricated metal-dielectric multilayers intended for passband filters in the ultraviolet range. We determined the dispersion characteristics by the Bloch approach to evanescent wave resonant coupling and calculated the spectral characteristics using the transfer matrix method while taking into account real dispersion and absorptive losses. We considered the influence of nanoscale interface roughness as a means to couple evanescent electromagnetic field to the propagating far field modes. In our structures both propagating and evanescent modes contribute to the overall performance, resulting in an enhanced transmission in the desired range, while retaining a strong suppression of undesired frequencies of more than four orders of magnitude. In our experiments we used radiofrequent sputtering of silver and silica and characterized our multilayers by UV-vis spectroscopy

Ultrafast humidity sensor based on liquid phase exfoliated graphene

Humidity sensing is important to a variety of technologies and industries, ranging from environmental and industrial monitoring to medical applications. Although humidity sensors abound, few available solutions are thin, transparent, compatible with large-area sensor production and flexible, and almost none are fast enough to perform human respiration monitoring through breath detection or real-time finger proximity monitoring via skin humidity sensing. This work describes chemiresistive graphene-based humidity sensors produced in few steps with facile liquid phase exfoliation (LPE) followed by Langmuir-Blodgett assembly that enables active areas of practically any size. The graphene sensors provide a unique mix of performance parameters, exhibiting resistance changes up to 10% with varying humidity, linear performance over relative humidity (RH) levels between 8% and 95%, weak response to other constituents of air, flexibility, transparency of nearly 80%, and response times of 30 ms. The fast response to humidity is shown to be useful for respiration monitoring and real-time finger proximity detection, with potential applications in flexible touchless interactive panels.Comment: 18 pages, 13 figure

A consideration of the use of ICTM SP-12 pressure sensor for ultrasound sensing

A consideration study for the application of the pressure sensor SP-12 developed and produced by ICTM CMT as an ultrasound sensor is given. The interaction of ultrasound with the sensor’s membrane was analytically described, but for the initial examination of its performance, Finite Elements Method simulation was applied. The sensor SP-12 has eigenfrequencies in the range from 200 kHz to the frequencies higher than 2 MHz. The amplitude of the output signal, which is proportional to Von Mises stress, is highest for the lowest frequency, and it exponentially decreases as the eigenfrequencies increase. This makes the sensor suitable for the ultrasound measurements in the range of hundreds of kH

Direct Laser Writing of micro-structures in vector mode for chemical sensors

Chemical sensors are the key part of the sensing platforms. They have different operating principles, but most of them are based on microstructures formed on the surface of the chip. In this paper we present technique for obtaining micro sized structures for the use in two different types of the chemical sensors. One type of the sensor is based on the electrical conductivity alteration in Au thin-film while the other is based on the optical properties of periodic metallic structures utilizing plasmonic effects. Technique presented here is based on the laser writing on the photosensitive material in “vector mode” where only continuous lines could be directly written. Width of the written lines is modified by alternating technique parameters. Narrowest obtained lines have width of about 1 m with clearance of about 3 m

Wet isotropic chemical etching of Pyrex glass with masking layers Cr/Au

In this paper we developed various techniques of wet isotropic chemical etching of Pyrex glass in an aqueous solution of 49% HF. The techniques are based on the processes of sputtering and photolithography. The various thin films of Cr/Au were sputtered. Layers of Cr/Au and photoresist serve as a masking material during etching of Pyrex glass in aqueous HF

Consideration of Thin Film Ionization Vacuum Pressure Sensor

A novel concept of vacuum pressure sensor based on thin film technology is presented. The sensor is designed as a 1 µm thick aluminium film patterned as a structure of wedges facing each other along a sharp tip. The distance between the wedge tips is 3 µm. This structure is obtained by laser writing in vector mode. Parts of the sensor structure are fabricated and measured. Analytical consideration of the proposed structure is given together with the concept of the experimental set up for testing of the senso

Aluminum-based self-powered hyper-fast miniaturized sensor for breath humidity detection

An aluminum-based, self-powered, miniaturized sensor for breath humidity detection is presented. The sensor is designed as an interdigitated capacitor made out of sputtered aluminum 1 % silicon (Al 1 %Si) thin film, 700 nm thickness, with digits 1.5 mm long, 0.01 mm wide and 0.01 mm clearance between them. The voltage on the open end of the sensor is generated when the surface is covered with a thin layer of water vapor, for instance if a person blows on it. The voltage generated is up to 1.5 V. The voltage generation is based on an electrochemical process of interaction between aluminum, water and oxygen from air, similar to the operation of an aluminum-air battery. The rise time of the signal during water vapor (or breath) detection is as small as 10 ms which makes it one of the fastest humidity sensors reported to date. The relaxation time is in the range of 50 ms. To make detection possible, the sensor surface needs to be activated by native oxide removal with the help of electric current and de-mineralized water droplet. Usability of the sensor was demonstrated in the detection of human breathing, where the sensor managed to follow the cycles of inhaling and exhaling.This is the peer-reviewed version of the article: Boskovic MV, Sarajlic M, Frantlovic M, Smiljanic MM, Randjelovic DV, Zobenica KC, Radovic DV, Aluminum-based self-powered hyper-fast miniaturized sensor for breath humidity detection, Sensors and Actuators: B. Chemical (2020), doi: [https://doi.org/10.1016/j.snb.2020.128635]Published version: [http://cer.ihtm.bg.ac.rs/handle/123456789/3678