Hybrid Nanowire Ion-to-Electron Transducers for Integrated Bioelectronic Circuitry

Abstract

Abstract.A key task in the emerging field of bioelectronics is the transduction between ionic/protonic and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics and are best supported by very different materials types -electronic signals in inorganic semiconductors and ionic/protonic signals in organic or bio-organic polymers, gels or electrolytes. Here we demonstrate a new class of organic-inorganic transducing interface featuring semiconducting nanowires electrostatically gated using a solid proton-transporting hygroscopic polymer. This model platform allows us to study the basic transducing mechanisms as well as deliver high fidelity signal conversion by tapping into and drawing together the best candidates from traditionally disparate realms of electronic materials research. By combining complementary n− and p−type transducers we demonstrate functional logic with significant potential for scaling towards highdensity integrated bioelectronic circuitry.

Near-thermal limit gating in heavily doped III-V semiconductor nanowires using polymer electrolytes

“…The InAs/GaSb CMOS inverter of Dey et al shows square-wave fidelity loss at ∼ 10 kHz [10]. We currently experience fidelity loss at ∼ 10 Hz due to the limited ionic conductivity of our PE, but our estimates suggest ∼ 1 kHz is possible with some engineering of the PE and device design [14], whilst MHz operation of other PE-gated devices is well established [15]. A key limitation of polyethylene oxide-based electrolyte gates is their strong affinity for water and hygroscopic nature, which makes their performance sensitive to ambient humidity and hydration accumulated during processing [14].…”

“…We currently experience fidelity loss at ∼ 10 Hz due to the limited ionic conductivity of our PE, but our estimates suggest ∼ 1 kHz is possible with some engineering of the PE and device design [14], whilst MHz operation of other PE-gated devices is well established [15]. A key limitation of polyethylene oxide-based electrolyte gates is their strong affinity for water and hygroscopic nature, which makes their performance sensitive to ambient humidity and hydration accumulated during processing [14]. We expect improved performance to be obtained by a shift to other electrolyte-gate materials see, e.g., discussion in Kim et al [15], as well as through further engineering of N A and the device architecture; this will be the subject of future work.…”

“…200 mg polyethylene oxide (molecular weight 200k -Aldrich) was dissolved in 10 mL methanol by sonication for 30 min. Addition of LiClO 4 is optional and provides no significant performance enhancement in our NWFETs [14]. For all of the PE gates used in this study, the polyethylene oxide is doped with LiClO 4 with a 1 : 10 LiClO 4 :PEO ratio.…”

“…The gel absorbs water providing an environment for mobile ions, either H + /OH − from dissociated H 2 O, or added salt, e.g., LiClO 4 [14]. Gating occurs by electric field driven ion migration with gate charge forming a concentric ion layer within ∼ 1 nm of the nanowire surface [15].…”

“…Additionally, PE gates are far simpler to produce than traditional metal-oxide wrap-gate structures [18][19][20][21] and utilise an intrinsically biocompatible material [22]. Nanopatterned PE gates have been used in applications from enacting external ionic doping of quantum devices [17,23] to ionic-to-electronic signal transduction [14]. Here we extend this to include improved p-type NWFETs for room temperature nanowire complementary circuits.…”