Sensitive Chirality Measurements with Electrical Readout Utilizing the CISS Effect

Chirality is a fundamental chemical property that can be found in almost all aspects of life. Generally, in nature chirality exists in only one of the possible enantiomeric forms. Bitter experience showed that chiral drugs having the same chemical composition but opposite chirality may have extremely different biological effects. It is therefore that detecting and quantifying chirality is important in multiple fields ranging from analytical and biological chemistry to pharmacology, biotechnology, and fundamental physics. To date, the most widely used analytical methods for chiral detection, remain the traditional approaches of measuring circular dichroism and optical rotation. However, these methods suffer from low signal-to-noise due to large time-dependent backgrounds and require complicated optical setups. Recent works associate circular dichroism measurements with the Chiral Induced Spin Selectivity (CISS) spin current measurements. The CISS effect relates the probability of electron spin transmission through chiral molecules to chirality. Depending on the handedness of the molecule, electrons of a certain spin can traverse the molecule more easily in one direction than in the other. It is therefore that the CISS effect could be utilized to electronically measure chirality using spin currents and spin induced dipoles. The review summarizes the different approaches for utilizing the CISS effect for electrical measurements of chirality. Starting with a Hall device that can measure the chirality of the lowest energetic CD band of a monolayer in dry or wet systems. Presenting an enhancement of the effect as well as achieving a wider CD spectrum using electrical gating. Going down to 100 molecules limit with full spectrum response utilizing electro-optical nano floret devices.

Automated summary

Chirality is a fundamental chemical property that exists in various aspects of life. Detecting and quantifying chirality are important in multiple fields, including analytical chemistry, biological chemistry, and pharmacology. Traditional methods for chiral detection have limitations, and recent research has proposed new approaches using spin currents. This review summarizes different methods for electrical measurements of chirality using spin currents.