In single-cell analysis, cellular activity and parameters are assayed on an individual, rather than population-average basis. Essential to observing the activity of these cells over time is the ability to trap, pattern and retain them, for which previous single-cell-patterning work has principally made use of mechanical methods. While successful as a long-term cell-patterning strategy, these devices remain essentially single use. Here we introduce a new method for the patterning of multiple spatially separated single particles and cells using high-frequency acoustic fields with one cell per acoustic well. We characterize and demonstrate patterning for both a range of particle sizes and the capture and patterning of cells, including human lymphocytes and red blood cells infected by the malarial parasitePlasmodium falciparum. This ability is made possible by a hitherto unexplored regime where the acoustic wavelength is on the same order as the cell dimensions.

In recent years there has been an explosion of methods for encapsulating cells in droplets. This review examines the state-of-the-art, including methods for active encapsulation.

The widespread introduction of white LEDs for illumination provides a unique opportunity to create an indoor positioning system that is flexible, accurate, and ubiquitous. Signals transmitted by the LEDs are used to determine the position of a person or object within a room. To take full advantage of this new opportunity, it is essential that comprehensive and robust international standards are developed before a plethora of incompatible proprietary systems flood the market. In this article, we discuss the very diverse range of potential applications of these future systems and their implications for the design of a new standard. Another consideration is that the transmission of positioning signals must not compromise the primary function of the LEDs, which is energy-efficient illumination, so visible flicker must be avoided. Position information can be derived from a range of properties of the received signal, such as the power of the received signal or the angle at which the signal reaches the receiver. The suitability of different techniques for an indoor positioning system is considered. Finally, we discuss the implications each of these aspects has for the design of an effective standard.

This paper reports an electrostatic microelectromechanical systems (MEMS) gripper with an integrated capacitive force sensor. The sensitivity is more than three orders of magnitude higher than other monolithically fabricated MEMS grippers with force feedback. This force sensing resolution provides feedback in the range of the forces that dominate the micromanipulation process. A MEMS ultrasonic device is described for aligning microobjects suspended in water using ultrasonic fields. The alignment of the particles is of a sufficient accuracy that the microgripper must only return to a fixed position in order to pick up particles less than 100 mum in diameter. The concept is also demonstrated with HeLa cells, thus providing a useful tool in biological research and cell assays

This paper analyzes an indoor positioning system that uses white lighting LEDs. Modulated signals transmitted by the LEDs are used as the basis of time-of-arrival-based distance estimation. The theoretical limits on the accuracy of estimation are calculated by deriving the Cramer-Rao bound for intensity modulated windowed sinusoidal signals. Calculations for a typical indoor scenario, assuming perfect synchronization between transmitter and receiver, but using realistic values for other parameters show that very accurate distance estimates are achievable, with typical errors being in the order of centimeters depending on the frequency and power of the sinusoidal signals, the distance from the LED and the properties of the LED and the photoreceiver.

We demonstrate the use of a highly focused surface acoustic wave (SAW) with an effective region only ~25 μm wide for precise manipulation on the single-particle level.