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Advances in the integration of wearable devices in our daily life have led to the development of new electrode designs for biopotential monitoring. Historically, the development and testing of wearable electrodes for the acquisition of biopotential signals has been empirical, relying on experiments on human volunteers. However, the lack of explicit control on human variables, the intra-, and inter-subject variability complicates the understanding of the performance of these wearable electrodes. Herein, phantom mimicking the electrical properties of the skin in the low-frequency range (1 Hz-1000 Hz), which has the potential to be used as a platform for controlled benchtop experiments for testing electrode functionality, is demonstrated. The fabricated phantom comprises two layers representing the deeper tissues and stratum corneum. The lower layer of the phantom mimicking deeper tissues was realized using polyvinyl alcohol cryogel (PVA-c) prepared with 0.9% W/W saline solution by a freeze-thaw technique. The properties of the upper layer representing the stratum corneum were simulated using a 100μm thick layer fabricated by spin-coating a mixture of polydimethylsiloxane (PDMS), 2.5% W/W carbon black (CB) for conductance, and 40% W/W barium titanate (BaTiO(3)) as a dielectric. The hydration of the stratum corneum was modeled in a controlled way by varying porosity of the phantom’s upper layer. Impedance spectroscopy measurements were carried out to investigate the electrical performance of the fabricated phantom and validated against the impedance response obtained across a physiological skin impedance range of five human subjects. The results indicated that the Bode plot depicting the impedance response obtained on the phantom was found to lie in the human skin range. Moreover, it was observed that the change of porosity provides control over the hydration and the phantom can be tuned as per the skin ranges among different individuals. Also, the phantom was able to mimic the impact of dry and hydrated skin on a simulated ECG signal in the time domain. The developed skin phantom is affordable, fairly easy to manufacture, stable over time, and can be used as a platform for benchtop testing of new electrode designs.

In-home physiological monitoring devices enable the monitoring of vital health parameters and can facilitate health recovery. The current state of the art is inclined towards non-invasive technologies such as wearable mobile devices and patch-based sensors. In this chapter, we provide an overview of progress made in the field of dry electrodes for biopotential acquisition, based on their mechanistic principles, materials, testing methods, and effectiveness in a real-world setting. Important parameters affecting the dry electrode performance such as the area, material, applied pressure and skin hydration are discussed. Traditionally, the development and testing of these wearable electrodes are conducted empirically, in vivo on human skin. However, due to the inter- and intra-subject variability in human skin properties, reliability, repeatability, and the efficacy of the device under investigation cannot be evaluated. Thus a review is presented about the skin phantoms used to simulate the electrical properties of the skin, which has the potential to serve as a robust method to test the functionality of current and future electrodes. This retrospective overview provides researchers with an understanding of the mechanistic principle of biopotential electrodes and the crucial factors that affect electrode performance, thus facilitating wearable electrode development.

We study an architecture for implementing adiabatic quantum computation with trapped neutral atoms. Ground state atoms are dressed by laser fields in a manner conditional on the Rydberg blockade mechanism, thereby providing the requisite entangling interactions. As a benchmark we study the performance of a Quadratic Unconstrained Binary Optimization (QUBO) problem whose solution is found in the ground state spin configuration of an Ising-like model. We model a realistic architecture, including details of the atomic implementation, with qubits encoded into the clock states of 133Cs, effective B-fields implemented through stimulated Raman transitions, and atom-atom coupling achieved by excitation to the 100P3/2 Rydberg level. Including the fundamental effects of photon scattering, we find the fidelity of two-qubit implementation to be on the order of 0.99, with higher fidelities possible with improved laser sources., 5 pages, 3 figures

We study the quantum phases of a three-color Hubbard model that arises in the dynamics of the p-band orbitals of spinless fermions in an optical lattice. Strong, color-dependent interactions are induced by an optical Feshbach resonance. Starting from the microscopic scattering properties of ultracold atoms, we derive the orbital exchange constants at 1/3 filling on the cubic optical lattice. Using this, we compute the phase diagram in a Gutzwiller ansatz. We find novel phases with 'axial orbital order' in which pz and px + ipy (or px - ipy) orbitals alternate., 4+epsilon pages, 3 figures. Similar to version published in PRA(R)

We study the use of an optical Feshbach resonance to modify the $p$-wave interaction between ultracold polarized $^{171}\mathrm{Yb}$ spin-$1/2$ fermions. A laser exciting two colliding atoms to the ${}^{1}{S}_{0}+{}^{3}{P}_{1}$ channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state $p$-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schr\"odinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic $p$-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized $^{171}\mathrm{Yb}$, where the three colors correspond to the three spatial orbitals of the first excited $p$ band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.