Electrochemical Nanoprobes for Single-Cell Analysis

The measurement of key molecules in individual cells with minimal disruption to the biological milieu is the next frontier in single-cell analyses. Nanoscale devices are ideal analytical tools because of their small size and their potential for high spatial and temporal resolution recordings. Here, we report the fabrication of disk-shaped carbon nanoelectrodes whose radius can be precisely tuned within the range 5–200 nm. The functionalization of the nanoelectrode with platinum allowed the monitoring of oxygen consumption outside and inside a brain slice. Furthermore, we show that nanoelectrodes of this type can be used to impale individual cells to perform electrochemical measurements within the cell with minimal disruption to cell function. These nanoelectrodes can be fabricated combined with scanning ion conductance microscopy probes, which should allow high resolution electrochemical mapping of species on or in living cells

Interactions of the μ{\mu}Al Acceptor Impurity in Lightly and Heavily-Doped Silicon

The work is devoted to investigation of the interactions of the aluminum acceptor impurity in silicon by means of polarized negative muons. The behavior of the negative muon polarization is studied for crystalline silicon samples with phosphorus (1.6\cdot 10^{13} cm^{-3}) and boron (4.1\cdot 10^{18} cm^{-3}) impurities. The measurements were carried out in a magnetic field of 0.41 T transverse to the direction of the muon spin in the temperature range 4-300 K. The obtained results evidence that in n-type phosphorus-doped silicon the {\mu}Al acceptor is ionized at T>50 K. In silicon with boron impurity a substantial deviation of the temperature dependence of the muon spin frequency shift from the 1/T Curie law is found at T{\le}50 K. The interactions of the {\mu}Al acceptor which may be the cause for the observed effects are analyzed

Investigation of the Mechanisms for Ionization of the Aluminium Acceptor Impurity in Silicon

The work is aimed to study the processes of ionization of shallow acceptor centres in silicon. Impurity atoms of _{\mu}Al in crystalline silicon samples with phosphorus (1.6\cdot 10^{13}, 2.7\cdot 10^{13} and 2.3\cdot 10^{15} cm^{-3}) and boron (1.3\cdot 10^{15} cm^{-3}) impurities were created via implantation of negative muons. The polarization of muons was studied in a magnetic field of 0.25 T transverse to the direction of the muon spin in the temperature range 10-300 K. Both in p-type silicon and in n-type silicon with impurity concentration \lesssim 10^{15} cm^{-3} the dominant mechanism for ionization of Al acceptor impurity at T > 45 K was proved to be thermal ionization. The rate for thermal ionization of aluminium acceptor in silicon varies from \sim 10^{5} to \sim 10^{6} s^{-1} in the temperature range 45-55 K