Abstract: An embodiment of a light powered transmitter configured for broadcasting an electromagnetic control field to a region is provided. The transmitter includes a housing having a longitudinal axis. The housing includes a photovoltaic cell configured to generate electrical power in response to light and a rechargeable power source configured to store at least a portion of the power generated by the photovoltaic cell. The housing also includes an electromagnetic transmitter and a directional antenna. The directional antenna can be configured to broadcast an electromagnetic (e.g., radio-frequency) control field to a region. The directional antenna can be rotatably mounted in the housing such that the antenna can be rotated around the longitudinal axis. The housing can further include a transparent or translucent optical element configured to receive the light and converge at least a portion of the light onto the photovoltaic cell.

Abstract: A wheel for a non-motorized vehicle (e.g., a shopping cart) can include a housing assembly and a tread assembly. The housing assembly can be configured to sealingly house electronics or other components. The tread assembly can removably mate with the housing assembly such that the electronics or other components remain closed and/or sealed within the housing assembly when the tread assembly is mated or unmated with the housing assembly.