Oligos Etc. of Wilsonville, Oregon has received US Patent No. 6,562,569, “Arrays with modified oligonucleotide and polynucleotide compositions.” The patent covers methods and compositions of arrays with modified oligonucleotides that bind either DNA or RNA. The arrays either have increased binding affinity with complementary RNA, or exhibit acid resistance, enabling treatment with low pH solutions. They can also be resistant to nuclease degradation.