One mil­lion vocal­ists singing the same song will sound cacoph­o­nous to an audi­ence member if the singers belt out the tune at dif­ferent tempos.

But if you’re lis­tening to one person sing, and he changes his tempo, you’re still going to stay in tune with him,” said Meni Wanunu, an assis­tant pro­fessor of physics in Northeastern’s Col­lege of Sci­ence.

Wanunu used the analogy to explain the dif­fer­ence between older and newer gene sequencing tech­niques. Old tech­niques, he said, ana­lyzed mil­lions of DNA mol­e­cules at a time. But new tech­niques take a single-​​molecule approach, a strategy that has the poten­tial to rev­o­lu­tionize the field — once a few sig­nif­i­cant chal­lenges are overcome.

By obtaining the sequence of an organism’s genetic mate­rial with ease, sci­en­tists can explore a range of research areas, from cor­re­lating genes with func­tions to answering evo­lu­tionary mys­teries. Doc­tors can use gene sequencing to test for spe­cific genes that are related to spe­cific dis­eases, such as breast and ovarian can­cers. Patients could learn in their home what foods to avoid and which drugs would be most effec­tive for them.

Older and cur­rent com­mer­cial sequencing tech­nolo­gies are too expen­sive for real­izing per­son­al­ized health and med­i­cine appli­ca­tions. By studying DNA motion through nanopores, Wanunu’s team and others in the field hope to pro­vide simple and straight­for­ward approaches that could reduce sequencing costs by a thou­sand times, making it avail­able for all.

In an article pub­lished on Sunday in the journal Nature Methods, Wanunu and col­leagues at Uni­ver­sity of Penn­syl­vania and Columbia Uni­ver­sity unveiled a device that speeds up the rate at which DNA mol­e­cules can be detected, a sig­nif­i­cant step toward reading their sequence.

Wanunu, who joined the North­eastern fac­ulty in Sep­tember, designs nanoscale mem­branes that con­tain pores through which charged par­ti­cles, such as DNA mol­e­cules and salt ions, can pass when exposed to an elec­tric field.

When a long DNA mol­e­cule passes through a pore, the membrane’s cur­rent momen­tarily sub­sides, yielding a neg­a­tive spike in voltage signal. DNA con­sists of many repeating sub­units called bases, each of which has pre­vi­ously been shown to exhibit a char­ac­ter­istic signal spike.

Existing state-​​of-​​the-​​art tech­niques can’t mea­sure cur­rent changes though a nanopore fast enough to allow reading each base. “You can show that DNA was there, but not what the sequence is,” Wanunu explained.

Slowing down DNA move­ment by low­ering the voltage is not a prac­tical solu­tion, Wanunu said. “If you lower the voltage too much, at some point DNA will not want to enter and if it doesn’t enter you won’t be able to read it. If it enters too fast, you’re not going to know the sequence.”

Armed with this infor­ma­tion, the team focused their efforts on speeding up the rate of mea­sure­ment. By thinking out­side the box (lit­er­ally), Wanunu’s col­leagues Jacob Rosen­stein and Ken Shepard from Columbia Uni­ver­sity designed a minia­ture “patch-​​clamp ampli­fier” that is 10 times smaller than tra­di­tional ampli­fiers. More impor­tantly, it is 10 times faster, being able to read cur­rent through the nanopore about every half microsecond — just about the time it takes for a DNA base to move through.

Sequencing DNA is one of many appli­ca­tions for this ampli­fier. It could also be useful for neu­ro­sci­en­tists in reading cell cur­rents, ana­lyzing RNA struc­tures and probing pro­teins. Wanunu plans to opti­mize the system, by focusing on the speed of DNA move­ment, on min­i­mizing the capacity for pores to clog and on iden­ti­fying stronger, thinner mem­brane mate­rials like graphene.