Abstract: A nano-sensor for sensing one or more targets has a plurality of sensor units, each including a nano-structure and an encapsulating sensible medium surrounding the nano-structure. Each nano-sensor unit being positioned by holographic optical trapping and operative to produce a signal output indicative of the presence of a particular target. A substrate has a sensor location for each sensor unit, each operative to produce an output in response to the signal from the corresponding sensor unit indicative of the presence of a particular target. The sensor may employ a disposable support for the sensor units adapted to be positioned in registration with the sensor locations and disposed of after use.