NANO TTER pubs. acs org/AnolE Kinked p-n Junction Nanowire Probes for High Spatial Resolution Sensing and Intracellular recording Zhe Jiang, Quan Qing" Ping Xie, Ruixuan Gao, and Charles M. Lieber**. I,F Department of Chemistry and Chemical Biology and 'School of Engineering and Applied Science, Harvard University, Cambridge Massachusetts 02138, United States S Supporting Information ABSTRACt: Semiconductor nanowires and other semi- onducting nanoscale materials configured as field-effect transistors have been studied extensively as biological/chemical (bio/chem) sensors. These nanomaterials have demonstrated high-sensitivity from one- and two-dimensional sensors, n although the realization of the ultimate pointlike detector has not been achieved. In this regard, nanoscale p-n diodes are attractive since the device element is naturally localized near the junction, and while nanowire p-n diodes have been widely studied as photovoltaic devices, their applications as bio/chem ensors have not been explored. Here we demonstrate that p-n diode devices can serve as a new and powerful family of highly localized biosensor probes. Designed nanoscale axial p-n junctions were synthetically introduced at the joints of kink nanowires. Scanning electron microscopy images showed that the kinked nanowire structures were achieved, and electrical transport measurements exhibited rectifying behavior with well-defined turn-on in forward bias as expected for a p-n diode In addition, scanning gate microscopy demonstrated that the most sensitive region of these nanowires was localized near the kinked region at the p-n junction. High spatial resolution sensing using these p-n diode probes was carried out in aqueous solution using fluorescent charged polystyrene nanobeads. Multiplexed electrical measurements show well-defined single-nanoparticle detection, and experiments with simultaneous confocal imaging correlate directly the motion of the nanobeads with the electrical signals recorded from the p-n devices. In addition, kinked p-n junction nanowires configured as three-dimensional probes demonstrate the capability of intracellular recording of action potentials from electrogenic cells. These p-n junction kinked nanowire devices, which represent a new way of constructing nanoscale probes with highly localized sensing regions, provide from within living cells and issue 3 substantial opportunity in areas ranging from bio/chem sensing and nanoscale photon detection to three-dimensional recording KEYWORDS: Nanosensor, nanoprobe, nanobioelectronics, nanoelectronic device, diode enabled many advances in functional nanoelectronics, -9 p-n junctions can be synthetically encoded in axial and core/ and moreover, have opened-up unique opportunities at the shell nanowires, 423, 4 although only the photovoltaic proper interface between nanoelectronics and biological systems. ties of such nanojunctions have been thoroughly studied.3,+ For example, recent studies have shown that nanoscale field- Such p-n diodes have not yet been investigated as bio/chem ffect transistors(nanoFETs)can be synthetically encoded at the sensors. Here we report a successful synthetic integration of tips of kinked silicon nanowires. These kinked nanostructures p-n junction in the kinked silicon nanowire structure, and study can be readily configured as three-dimensional(3D) bioprobes, for the first time both experimentally and theoretically these which enabled recording intracellular action potentials from devices as highly localized electronic biosensors. In particular, beating cardiomyocytes in a minimally invasive manner. This we focus on the use of p-n junction kinked nanowire devices work represented the first demonstration of internalizing an for charge sensing down to the single nanoparticle level, and for active electronic probe, a transistor, which was comparable in size intracellular potential recording within live cells. to viruses and many biological macromolecules inside a cell Kinked p-n junction silicon nanowires(SiNWs)were While these studies open up a new paradigm for integrating synthesized by gold nanoparticle-catalyzed chemical-vapor- electronics with cells and tissue, they are also potentially limited deposition( CVD) process with doping and geometric control in that synthetic preparation of an ideal pointlike nanoFET detector is challenging Received: January 20, 2012 In this regard, nanoscale p-n diodes are attractive since the Revised: February 6, 2012 device element is naturally localized at the depletion region of Published: February 6, 2012 ACS Publications o 2012 American Chemical Society 1711 dxdoloro/o.102/nl300256r| Nano Lert.2012,12.1711-1716Kinked p−n Junction Nanowire Probes for High Spatial Resolution Sensing and Intracellular Recording Zhe Jiang,†,§ Quan Qing,†,§ Ping Xie,† Ruixuan Gao,† and Charles M. Lieber*,†,‡ † Department of Chemistry and Chemical Biology and ‡ School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138, United States *S Supporting Information ABSTRACT: Semiconductor nanowires and other semi￾conducting nanoscale materials configured as field-effect transistors have been studied extensively as biological/chemical (bio/chem) sensors. These nanomaterials have demonstrated high-sensitivity from one- and two-dimensional sensors, although the realization of the ultimate pointlike detector has not been achieved. In this regard, nanoscale p−n diodes are attractive since the device element is naturally localized near the junction, and while nanowire p−n diodes have been widely studied as photovoltaic devices, their applications as bio/chem sensors have not been explored. Here we demonstrate that p−n diode devices can serve as a new and powerful family of highly localized biosensor probes. Designed nanoscale axial p−n junctions were synthetically introduced at the joints of kinked silicon nanowires. Scanning electron microscopy images showed that the kinked nanowire structures were achieved, and electrical transport measurements exhibited rectifying behavior with well-defined turn-on in forward bias as expected for a p−n diode. In addition, scanning gate microscopy demonstrated that the most sensitive region of these nanowires was localized near the kinked region at the p−n junction. High spatial resolution sensing using these p−n diode probes was carried out in aqueous solution using fluorescent charged polystyrene nanobeads. Multiplexed electrical measurements show well-defined single-nanoparticle detection, and experiments with simultaneous confocal imaging correlate directly the motion of the nanobeads with the electrical signals recorded from the p−n devices. In addition, kinked p−n junction nanowires configured as three-dimensional probes demonstrate the capability of intracellular recording of action potentials from electrogenic cells. These p−n junction kinked nanowire devices, which represent a new way of constructing nanoscale probes with highly localized sensing regions, provide substantial opportunity in areas ranging from bio/chem sensing and nanoscale photon detection to three-dimensional recording from within living cells and tissue. KEYWORDS: Nanosensor, nanoprobe, nanobioelectronics, nanoelectronic device, diode The rational design and synthesis of nanomaterials have enabled many advances in functional nanoelectronics,1−9 and moreover, have opened-up unique opportunities at the interface between nanoelectronics and biological systems.2,10−21 For example, recent studies have shown that nanoscale field￾effect transistors (nanoFETs) can be synthetically encoded at the tips of kinked silicon nanowires.2,5 These kinked nanostructures can be readily configured as three-dimensional (3D) bioprobes, which enabled recording intracellular action potentials from beating cardiomyocytes in a minimally invasive manner.2 This work represented the first demonstration of internalizing an active electronic probe, a transistor, which was comparable in size to viruses and many biological macromolecules inside a cell. While these studies open up a new paradigm for integrating electronics with cells and tissue, they are also potentially limited in that synthetic preparation of an ideal pointlike nanoFET detector is challenging. In this regard, nanoscale p−n diodes are attractive since the device element is naturally localized at the depletion region of the junction.22 A number of previous studies have shown that p−n junctions can be synthetically encoded in axial and core/ shell nanowires,3,4,23,24 although only the photovoltaic proper￾ties of such nanojunctions have been thoroughly studied.3,4 Such p−n diodes have not yet been investigated as bio/chem sensors. Here we report a successful synthetic integration of p−n junction in the kinked silicon nanowire structure, and study for the first time both experimentally and theoretically these devices as highly localized electronic biosensors. In particular, we focus on the use of p−n junction kinked nanowire devices for charge sensing down to the single nanoparticle level, and for intracellular potential recording within live cells. Kinked p−n junction silicon nanowires (SiNWs) were synthesized by gold nanoparticle-catalyzed chemical-vapor￾deposition (CVD) process with doping and geometric control Received: January 20, 2012 Revised: February 6, 2012 Published: February 6, 2012 Letter pubs.acs.org/NanoLett © 2012 American Chemical Society 1711 dx.doi.org/10.1021/nl300256r | Nano Lett. 2012, 12, 1711−1716