Hannah R Kempton1, Lei S Qi2,3,4. 1. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. 2. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. stanley.qi@stanford.edu. 3. Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA. 4. Stanford ChEM-H Institute, Stanford University, Stanford, CA 94305, USA.