Tree fruit postharvest chemical sensor
An electrochemical sensor for organic molecules such as ethylene includes an electrochemical cell, gas sample inlet means and means for detecting current produced by the oxidation of the organic molecule at the anode of the cell. The sensor is capable of sensing multiple organic molecules in some embodiments. A voltage is applied to the anode of the cell to provide energy to drive the oxidation reaction and produce a corresponding current. The sensor of the invention can be made as a small, hand-held unit that is capable of real-time detection of various organic species.
1. A sensor comprising a) an electrolytic cell having an anode that adsorbs ethylene, b) means for measuring current created by an electrocatalytic reaction of ethylene at the anode, c) and intake means for supplying a sample gas to the anode, wherein the electrolytic cell includes (1) a front housing that includes a gas inlet and a gas outlet, (2) a rear housing that includes a cavity for containing said electrolyte; and (3) an anode positioned between said front and rear housings, wherein said anode is supported to minimize or eliminate flexing and is exposed on one side to the electrolyte contained in the cavity in said rear housing and on the other side to a sample gas in the front housing, and further wherein the front housing includes a microchannel geometry or surface features which produce turbulent flow characterized by a Reynolds number of at least 500 in a sample gas flowing through said front housing at a flow rate of from 5 to 3000 sccm and still further wherein the front housing functions as a working electrode and the rear housing contains multiple support pegs which provide mechanical support and current collection capability to the anode, wherein the electrolytic cell detects the presence of ethylene in a gas stream at levels as low as 10 parts per billion.
2. The sensor of claim 1 , wherein said rear housing includes inlet and outlet ports for filling, emptying and recirculation of an electrolyte.
3. The sensor of claim 1 wherein the anode includes a solid-semi-permeable membrane that is coated or plated with gold.