Ponente: Dr. Dietmar Fink
Institución: Helmholtz-Zentrum fur Materialen und Energie (Alemania)
Hora de inicio: 17:30:00
Lugar: Auditorio ICF
The impact of swift heavy ions onto insulators such as polymers or SiO2 creates long narrow trails of damage --the so-called ion tracks-- which often can be etched, resulting in the formation of nanopores. Their shapes can be tailored by the choice of adequate parameters governing the projectiles, the targets and the etching process. Specifically, conical tracks submersed in electrolytes show a current rectifying behavior upon application of a voltage, and under certain circumstances are also capable to emit current spikes. These properties are used in several biosensing and biomimetic concepts.
1.For biosensing, the walls of narrow but long conical tracks are clad with, e.g. enzymes. Upon arrival of small amounts of an agent, the enzymatic reaction products enrich inside the tracks which leads to changes in the pH values and consequently in the track resistance.
2.Fields of current spike-emitting tracks that interact with each other show the tendency to synchronous oscillations, with the oscillation pattern being determined by details of the track interaction. This resembles to the interaction of neurons in the human brain so that neural network theory can be applied to pulsating track fields.
3.Each nanoporous membrane submerged in an electrolyte separates the latter into two compartments. Correspondingly, the insertion of two parallel membranes leads to 3-compartment structures. Such structures exhibit the possibility of multiple tuning, by either modifying the electrolyte composition in one or more compartments, or by applying electrical potentials to the central electrolytic compartment or to contacts deposited on the tracks.
4.It had been shown earlier that conducting nanoporous membranes on top of silicon wafers lead to specific, so-called TEMPOS structures that exhibit quite a number of peculiarities such as tunable pn-to–np transition, tunable negative differential resistances, analogous AND or OR logic decision making, electroluminescence and sensing of physical (e.g. potentials, light, magnetic fields,…) or chemical parameters (e.g. humidity, alcohol, ammonia,…).
It is our aim to combine the above-mentioned approaches with each other to create nanostructures of a higher degree of complexity with yet unknown new properties:
a)The combination of both, track-based biosensing (#1) and TEMPOS structures (#4) should lead to tunable biosensors with higher sensitivity and faster response times.
b)The combination of both, current spike emission (#2) and multiple tuning (#3) in one system should make such systems more biomimetic as they will resemble closer to natural neural networks.
c)The combination of both, neural network-type structures (#2) and TEMPOS structures (#4) should bridge the worlds of bioelectronics and digital electronics.