A Fully Integrated Wireless Flexible Ammonia Sensor Fabricated by Soft Nano-Lithography

Abstract

Flexible ammonia (NH 3 ) sensors based on one-dimensional nanostructures have attracted great attention due to their high flexibility and low power consumption. However, it is still challenging to reliably and cost-effectively fabricate ordered nanostructure-based flexible sensors. Herein, a smartphoneenabled fully integrated system based on a flexible nanowire sensor was developed for real-time NH 3 monitoring. Highly aligned, sub-100 nm nanowires on a flexible substrate fabricated by facile and low-cost soft lithography were used as sensitive elements to produce impedance response. The detection signals were sent to a smartphone and displayed on the screen in real time. This nanowirebased sensor exhibited robust flexibility and mechanical durability. Moreover, the integrated NH 3 sensing system presented enhanced performance with a detection limit of 100 ppb, as well as high selectivity and reproducibility. The power consumption of the flexible nanowire sensor was as low as 3 μW. By using this system, measurements were carried out to obtain reliable information about the spoilage of foods. This smartphone-enabled integrated system based on a flexible nanowire sensor provided a portable and efficient way to detect NH 3 in daily life.

Rapid and Selective NH3 Sensing by Porous CuBr

“…Polyaniline sensors detect 40 ppb NH 3 at ≥90% RH,9 but these are usually for single‐use only as they recover too slowly. Other polymers like PEDOT:PSS nanowires feature higher LODs of 100 ppb,10 which is even higher for carbon‐based reduced graphene oxide (1.2 ppm in dry air)11 and 3D sulfonated reduced graphene oxide hydrogels (1.5 ppm) 12. Finally, metal‐oxides can also detect sub‐ppm NH 3 concentrations (e.g., Si‐doped MoO 3 with LODs of 51 ppb at 90% RH25 and pure MoO 3 of 280 ppt in dry air26) but these require typically elevated operational temperatures (e.g., 400–450 °C).…”

“…Other NH 3 sensors feature lower selectivities to these analytes. In fact, polymer‐based PEDOT:PSS nanowires10 are quite sensitive to ethanol (NH 3 selectivity ≈15 vs CuBr 38 from Figure 5) while composites of polyaniline and multi‐walled carbon nanotubes13 showed only moderate selectivity over acetone (7 vs CuBr 57 from Figure 5). Also metal‐oxides like pure or Si‐MoO 3 possess only moderate selectivity over acetone (3.6) 25.…”

Flexible and Robust Electro‐Optically Responsive Films Based on Novel Silica/Oligoaniline/Carbon Dots Composite

“…1 H NMR (DMSO-d 6 , ppm): δ = 8.09 (s, À CONHÀ ), δ = 7.73-7.50 (m, À NHÀ ), δ = 7.28-6.68 (m, ArÀ H), δ = 6.02 (m, À CONHÀ ), δ = 3.74 (m,À OÀ CH 2 À from ethoxy groups), δ = 3.03 (m, À CH 2 À next to urea group), δ = 1.46 (m, À CH 2 À ), δ = 1.14 (m, À CH 3 from ethoxy groups), δ = 0.54 (m, À CH 2 À SiÀ (À OÀ ) 3 ). The reaction was kept with magnetic stirring at 60°C for 5 h. The resultant tetraaniline-functionalized siloxane compound was defined as TAÀ Si.…”

“…[1][2][3][4] Organic semiconductors, especially those based on conjugated polymers, are promising towards these ends and have been explored extensively. [1][2][3][4] Organic semiconductors, especially those based on conjugated polymers, are promising towards these ends and have been explored extensively.…”

“…The demand for robust and reliable materials applicable to flexible electronics, displays, and sensors continues. [1][2][3][4] Organic semiconductors, especially those based on conjugated polymers, are promising towards these ends and have been explored extensively. [5][6][7][8] While these materials offer extraordinary properties, production scale manufacturing of devices based on many of these materials remains a chemistry and engineering challenge due to a variety of factors.…”