Results: 4

1.
Figure 4

Figure 4. Multiplexed ANTT probes. From: Outside Looking In: Nanotube Transistor Intracellular Sensors.

(A) Design and SEM image of a probe with two independent ANTT devices sharing a common source contact. Horizontal scale bar, 5 μm. (B) Intracellular recording from a single cardiomyocyte using a probe with two independent ANTT devices. The interval between tick marks corresponds to 1 s. (C) SEM image of part of an ANTT probe array fabricated from contact printed Ge/Si NWs. Scale bar, 2 μm. Inset, lower magnification SEM image of the 4 × 4 probe array. Scale bar, 100 μm. Probe interval is about 80 μm. (D) Schematic of chip-based vertical ANTT probe arrays fabricated using epitaxial Ge/Si NWs for enhanced integration.

Ruixuan Gao, et al. Nano Lett. ;12(6):3329-3333.
2.
Figure 3

Figure 3. Action potential recording with ANTT probes. From: Outside Looking In: Nanotube Transistor Intracellular Sensors.

(A) Representative potential vs. time data recorded immediately following contact between the ANTT probe and a single cardiomyocyte. (B) Representative potential vs. time data recorded ca. 100 s following contact between the ANTT probe and a single cardiomyocyte and the trace in A. (C) Stable potential vs. time data recorded ca. 5 min following trace B. The tick marks in A-C correspond to 1 s. (D) Zoom of the single intracellular action potential peak in trace C highlighted with the dashed box. The five characteristic phases of the action potential peak, denoted by 1-5, are defined in text. In all the traces, the recorded device conductance was calibrated with the measured water-gate sensitivity to yield the plotted voltage signal.

Ruixuan Gao, et al. Nano Lett. ;12(6):3329-3333.
3.
Figure 2

Figure 2. Potential and chemical sensitivities of ANTT devices. From: Outside Looking In: Nanotube Transistor Intracellular Sensors.

(A) Change of conductance, ΔG, versus water-gate potential, Vwg, prior to (1) and after (2) H2O2 etching of the Ge NW core.14 Plots (3) and (4) correspond to ΔG versus Vwg for a Si/Si intrinsic-core/p-shell NW device before and after, respectively, etching using the same conditions as for the Ge/Si NW structure. All measurements were made in 1× phosphate-buffered saline (1×PBS) with a Ag/AgCl reference gate electrode. Insets, schematics of an ANTT device prior to (1) and after (2) H2O2 etching of the Ge NW core (colored deep red). (B) Change in potential, ΔV, in response to step changes in solution pH. The potential values were calculated from the measured ANTT device conductance using the measured water-gate sensitivity of 2.0 μS/V. Inset, ΔV as the pH is increased stepwise from 7.0 to 8.0 for an ANTT device (5) and the same device after closing the tip with SU-8 resist to prevent solution access (6).

Ruixuan Gao, et al. Nano Lett. ;12(6):3329-3333.
4.
Figure 1

Figure 1. Principle and fabrication of the ANTT probe. From: Outside Looking In: Nanotube Transistor Intracellular Sensors.

(A) Schematic view of an ANTT probe inserted into a cell and recording an intracellular action potential (Vcell vs. time, t) as a conductance (G) change in the active FET region between S/D contacts. Sensitivity to voltage changes from the external extracellular environment is effectively eliminated by SU-8 passivation of the nanotube region around the S/D contacts. The nanotube is shown as a half-cylinder for clarity. (B) Overview of the steps used for ANTT probe fabrication:14 (1) Transfer of Ge/Si core/shell nanowires (Ge/Si NWs) to a SU-8 layer that was deposited and prebaked on a sacrificial layer (colored silver). (2) Registration of positions of Ge/Si NWs and definition of the bottom SU-8 layer. (3) Definition of S/D metal contacts followed by the top SU-8 passivation layer. Final etching of the sacrificial layer and Ge NW core yields the Si ANTT probe. (C) Schematic of the completed ANTT probe following release from the substrate. (D) Scanning electron microscopy (SEM) image of an ANTT probe. Scale bar, 10 μm. Inset, zoom of the probe tip from the dashed red box. Scale bar, 100 nm.

Ruixuan Gao, et al. Nano Lett. ;12(6):3329-3333.

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