Zhao Group - Sensors & Bionics

Sensors & Bionics

We aim to understand fundamental electrochemical (electron transfer) processes in biological systems and also apply this knowledge to prototyping electronic devices such as sensors and bionics. Our research in this area includes ionic liqud-based gas sensors, imaging the activity of biomolecules and cells coupled to artificial systems, biomolecule-based semiconductors, cell adhesion & biofilms.

Smart Ionic Liquids–Based Microarray Gas Sensors

Aqueous/organic solvents electrolytes are most commonly used in current commercial electrochemical gas sensors. However, these conventional electrolytes are prone to drying out which limit the device life time. Ionic liquids (ILs) are attractive “green” (environmentally friendly) solvents and have negligible vapour pressure (they will never evaporate), wide electrochemical window, thermal stability, and wide range of solubilities. We are developing arrays of IL microdroplets which are applied for detect of gaseous coumpounds released from numerous anthropogenic sources including waste water, sewage treatment, farms and industry. These sensors are small, specific to the target gas, sensitive, fast in response and portable

                   

References: (a) Robust and versatile ionic liquid microarray achieved by microcontact printing, Nature Communications, 2014, 5, 3744; (b) Salt-on-a-chip: Microcontact Printing of Thiol-Functionalised Ionic Liquids for “Membrane-less” and “Spill-less” Gas Sensors, ACS Applied Materials & Interfaces, 2016, 8, 31368−31374.

Bionic Ears and Eyes - Neural Prostheses

Neural prostheses are a series of devices that can substitute a motor, sensory or cognitive modality that might have been damaged as a result of an injury or a disease. The success of Cochlear implants has been appreciated by over 170,000 children and adults worldwide for hearing loss treatment. The design of next-generation bionic ear and eye devices requires greater numbers of microelectrode array. We have developed an effective way to improve the microelectrode performance for high-resolution and site-specific neural prostheses through the Bionic Vision Australia program and an ARC likage grant with the world-leading heraing implant company, Cochlear Ltd.

  
References: Investigating the interfacial properties of electrochemically-roughened platinum electrodes for neural stimulation. Langmuir, 2015, 31, 2593−2599. 

Electroactive Biomaterials

Amino acids are key building blocks for polymeric macromolecules, especially proteins. Recently, we have discovered the world's first amino acid semiconductor formed as a charge transfer compound between neutral L-proline and tetracyanoquinodimethane. This discovery offers enormous potential for development of other biomaterials with semiconducting properties, and would provide biomimetic surfaces for "tethering" biomolecules which can be employed in biosensing and bioreactor applications.

References: (Pro2H+)2(TCNQ.-)2-TCNQ: an amino acid derived semiconductor, Angew. Chem. Int. Ed., 2011, 50 1589-1592

Smart Sensors On a Chip

Biosensors can use biological recognition elements (DNA, proteins, cells...) to detect specific molecules typically at low concentrations. When such sensors are fabricated into micro- and nano-metre scale, their performance can be dramatically improved because of increased mass transport, decreased background current and reduced ohmic drop. We utilize modern micro- and nano-fabrication techniques to generate two types of sensor device: (i) Array sensors, an assembly of microsensors operated in parallel; and (ii) Sensor arrays, independent addressable microsensors used to construct multianalyte sensors.

References: (a) Microfabrication of patterns of adherent marine bacteria Phaeobacter inhibens using soft lithography and scanning probe lithography. Langmuir 2010, 26, 8641-8647; (b) Scanning electrochemical microscopy for detection of biosensor and biochip surfaces with immobilized pyrroloquinone-dependent glucose dehydrogenase as enzyme label. Biosens. & Bioelectron., 2005, 20, 1277-1284