Nanoporous platinum solid-state reference electrode with layer-by-layer polyelectrolyte junction for pH sensing chip

Abstract

A novel solid-state reference electrode was developed by combining nanoporous Pt with polyelectrolyte junction. The polyelectrolyte junction was formed in the microchannel connecting the nanoporous Pt and the sample solution, and had layer-by-layer structure of oppositely charged polyelectrolytes. The layer-by-layer polyelectrolyte junction effectively blocked the mass transport of ions and maintains constant pH environments on the surface of the nanoporous Pt. The assembly of the polyelectrolyte junction and the nanoporous Pt, which produced reportedly a stable open-circuit potential in response to constant pH, exhibited outstanding performance as a solid-state reference electrode (e.g., excellent reproducibility of ±4 mV (n = 5), good long term stability of ±1 mV (for 50 h), and independence of solution environments like pH and ionic strength). A working principle of the solid-state reference electrode with layer-by-layer polyelectrolyte junction was suggested in terms of the roles of each layer and the effect of the neighboring layer. As a demonstrative application of the solid-state reference electrode, a miniaturized chip-type solid-state pH sensor comprised of two nanoporous Pt electrodes and a micro-patterned layer-by-layer polyelectrolyte junction was developed. The solid-state pH sensing chip showed reliable pH responses without liquid junction and successfully worked in a variety of buffers, beverages, and biological samples, showing its potential utility for practical applications. In addition, the solid-state pH sensing chip was integrated in a microfluidic system to be utilized for pH monitoring in microfluidic flow.

Biyosensörler ve Nanoteknolojik Etkileşim

“…Ayrıca, moleküllerin temel yapılarını çoğaltma ve görüntüleme yöntemlerinin hızla gelişmesi, nanoteknoloji ile birlikte değerlendirilmesi, nükleotit esaslı biyosensörlerin kullanım alanlarının daha da yaygınlaşmasına neden olacaktır [26,27]. Sağlık alanında kullanılan nano boyutlu biyosensörler ilk olarak Dr. Meyyappan tarafından yarı iletken biçiminde tasarlanmış ve küçük moleküllerin büyük moleküllere dönüştürülmesi sayesinde karbon nanotüp yapılar incelenmeye başlanmıştır [28]. Yapılan araştırmalar sonucu karbon nanotüp yapılar biyoalgılayıcı ve elektronik parçaların küçültülmesi çalışmaların eşlenmesi biyolojik sistemlerdeki elektrik veya elektrokimyasal sinyallerin tanınması ve okunabilmesini sağlar [29].…”

Multifunctional Water Sensors for pH, ORP, and Conductivity Using Only Microfabricated Platinum Electrodes

“…The lifetime of the SSREs can be extended by using barrier layers over the deposited AgCl to lower the AgCl dissolution rate [ 6 , 7 , 8 ]. Substantial research has also focused on the identification of new stable SSRE chemistries [ 9 , 10 , 11 ], but most of them still require membranes to block the interfering ions from the solution. The other challenging component is the pH sensing system, because pH sensors have to be insensitive to the environment except for the existence of hydronium ions.…”

Development of a Flexible Non-Metal Electrode for Cell Stimulation and Recording

“…Thus researchers have begun to search for alternative conductive materials such as carbon nanotubes, silver chloride ink, etc. [10,11,12,13,14], and non-brittle materials or flexible substrate materials such as PET, polyimide (PI), and polydimethylsiloxane (PDMS) [15,16,17] to address these problems while improving biocompatibility, flexibility and endurance.…”