A sheath useful for remote steering, guidance andor manipulation of a flexible instrument, including e. A desired transaction involving a holder of the account and the business entity may be generated based on the transaction history and a metric. An optical detector disposed above the light collecting layer detects light passing through the light collecting layer. First and second dc bias voltages applied to the gate and drain respectively cause the transistor to operate at a quiescent bias point in a saturated region of the transistor I-V plane.